Therapeutic Intervention for Trunk Control Impairments in Central Nervous System Disorders: A Comprehensive Review of Methods and Efficacy

ABSTRACT

Objectives: Trunk control involves multiple brain regions related to motor control systems. Therefore, patients with central nervous system (CNS) disorders frequently exhibit impaired trunk control, decreasing their activities of daily living (ADL). Although some therapeutic interventions for trunk impairments have been effective, their general effects on CNS disorders remain unclear. This review aimed to clarify this issue in patients with stroke, cerebellar ataxia, and Parkinson’s disease (PD), representing trunk control impairment by lesions in the cortical and corticospinal systems, cerebellum, and basal ganglia, respectively.

Methods: Using online databases, we searched for randomized controlled trials that investigated the effects of therapeutic interventions for trunk impairments in patients with stroke, cerebellar ataxia, and PD, reported in English from 2013 to 2023.

Results: Overall, 50 articles were reviewed. Core-stability exercise (CSE), which activates the trunk muscles, specifically in the lumbar and pelvic areas, through postural adjustment tasks, is effective in patients with stroke, cerebellar ataxia, and PD. Weight-shifting exercise, unstable surface training, training with transcutaneous electrical stimulation, and noninvasive brain stimulation have been effective in patients following stroke. The combination of CSE with task-oriented training based on daily activities has been effective in patients with cerebellar ataxia. Perceptual training, repetitive trans-spinal magnetic stimulation, and aquatic training effectively improved alignment and balance function in patients with PD.

Conclusions: This review provides evidence-based strategies to improve trunk control, ADL, and quality of life for patients with trunk control impairments caused by CNS disorders.

INTRODUCTION

Trunk control impairment decreases mobility, activities of daily living (ADL), and social participation in patients with central nervous system (CNS) disorders. It is associated with high rates of falls and increased risk of exacerbated disability, hospitalization, and death.^1,2,3) The severity of trunk impairment is correlated with hospital stay duration and ADL level at discharge in these patients.^4,5,6,7)

Trunk control is defined as an ability to adjust the trunk position to maintain body posture, regulate weight transfer, and maintain the center of gravity within the base of support, with or without external perturbation.⁸⁾ It provides stability during head and limb movement.⁹⁾ During trunk control, the motor cortex and corticospinal tract are involved in voluntary trunk movements and anticipatory postural adjustments, such as activation of the trunk muscles before limb movements.¹⁰⁾ When lesions occur in the motor cortex or corticospinal tract, trunk muscles may become paralyzed, abnormally increase their tonus, and show insufficient anticipatory postural adjustment, resulting in trunk control impairment.¹¹⁾

The cerebellum coordinates the timing of muscle activity in both the execution of voluntary movements and associated postural control in anticipatory postural adjustment. The cerebellar vermis modulates trunk muscle tonus to maintain balance via the vestibulocerebellar and spinocerebellar pathways. Damage to the cerebellar system impairs intermuscular coordination and decreases trunk muscle tone.^12,13,14)

The basal ganglia are also involved in trunk control by disinhibiting the cerebral cortex and brainstem through corticoreticular and reticulospinal projections, resulting in anticipatory postural adjustment preceding fine movements.¹⁵⁾ Damage to the basal ganglia causes postural abnormalities, particularly verticality.^16,17) Patients with Parkinson’s disease (PD) show an impaired righting response, abnormal tonus of the trunk muscles, and abnormal verticality that may include stooped posture, dropped head syndrome, and camptocormia.¹⁷⁾

Improving trunk control is important for mobility, ADL, social participation, quality of life (QOL), and fall prevention in these patients. Several rehabilitation programs have improved trunk control. However, there has been no comprehensive review of their effectiveness in patients with CNS disorders caused by damage to the cortical and corticospinal systems, cerebellum, or basal ganglia, typically represented by motor-cortical and subcortical stroke, cerebellar ataxia, and PD. Differences in interventions for the trunk control disorders caused by these diseases are also unclear. Therefore, this review considers the effects of rehabilitation training on trunk control impairments in these patients.

METHODS

A comprehensive review was conducted using the following databases: PubMed, PEDro, Google Scholar, and Web of Science. We applied the following inclusion criteria to ensure the relevance, quality, and consistency of the studies: studies published between 1 January 2013 and 31 December 2023, to focus on developments in interventions during the most recent decade; articles published in English, to ensure that we could accurately assess the content; peer-reviewed original research articles with randomized controlled trials, to maintain the quality and reliability of the findings; and studies involving patients with trunk control impairments caused by stroke, cerebellar ataxia, or PD. The following exclusion criteria were applied: studies published before 1 January 2013; articles not published in English; non-peer-reviewed articles; peer-reviewed articles without randomized controlled trials; studies that did not involve patients with trunk control impairments caused by stroke, cerebellar ataxia, or PD; and studies that evaluated only standing function, because lower limb function, in addition to trunk function, also largely affects the results.

Databases were searched using the following key terms: (trunk OR sitting OR “core stability”) AND (stroke OR hemiplegia OR cerebellar OR ataxia OR Parkinson). The literature search used the key terms and the principle of combining a free word search based on the search engine, subject headings, and keywords. We added the following keyword search: core stability exercises, weight transfer, unstable seating surface, electrical stimulation, noninvasive brain stimulation (NIBS), transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS), and whole body vibration (WBV). The primary outcome was a direct evaluation of trunk function, such as the Trunk Impairment Scale (TIS), Trunk Control Test, Functional Assessment for Control of Trunk, Function in Sitting Test (FIST), or range of movements of the trunk. Subsequently, we reviewed the titles and abstracts to assess whether the studies met the predetermined inclusion criteria.

Each retrieved study was qualitatively evaluated by classifying the evidence classes (from I to IV).^18,114) A Class I study was defined as a randomized, sham-controlled clinical trial including 50 or more patients receiving the target intervention, with a clearly reported primary outcome, exclusion/inclusion criteria, randomization/blinding procedure, and statistical analyses. Class I studies also considered study bias (caused by the heterogeneity of baseline characteristics among treatment groups), possible carry-over effects (for crossover studies), and dropouts. A Class II study was a randomized, placebo-controlled trial of 30–50 patients receiving the target intervention with the same high levels of methodological quality as a Class I study or a study with a larger sample but not meeting all the aforementioned criteria of high methodological quality. A Class III study was a controlled trial with lower methodological quality or a study with less than 30 patients receiving the target intervention. A Class IV study was an uncontrolled or case series study.

RESULTS

Overall, 364 articles were retrieved from the database search. Of these, 50 articles met the inclusion criteria and were reviewed. Approaches for improving trunk control in CNS disorders were extracted and summarized for stroke, cerebellar ataxia, and PD.

Stroke

We reviewed studies of patients with ischemic or hemorrhagic stroke in the cortical or subcortical regions with hemiplegia, excluding those with cerebellar damage (Table 1).

Table 1. Characteristics of primary research on impaired trunk control in stroke

Authors (year)	Intervention	Study design	Class	n (I/H)	Stroke phase (time since onset)	Procedure	Frequency	Result
Core-stability exercise (CSE)
Cabanas-Valdes et al. (2015) 21)	CSE	SB, RCT	III	79 (64/15)	Acute and Subacute phase (5–43 days)	E: CSE (15 min) + conventional physical therapy (60 min) C: conventional physical therapy (60 min)	25 sessions, 15 min/day, 5 days/week, 5 weeks	Greater improvement in TIS, FIST, BBA, BBS, Tinetti test, PASS, BI than control (P < 0.05)
Haruyama et al. (2017) 85)	CSE for abdomen and pelvis	SB, RCT	III	32 (14/18)	Subacute phase (1–5 months)	E: CSE consisting of abdominal drawing-in and pelvic exercises (20 min) + conventional physical therapy (40 min) C: conventional physical therapy (60 min)	20 sessions, 20 min/day, 5 days/week, 4 weeks	Greater improvement in TIS, active range of pelvic tilt, Brief-BESTest than control (P < 0.001) No difference in FRT, TUG, FAC between both groups
Park et al. (2019) 86)	CSE and aquatic CSE	SB, RCT	III	29 (15/14)	Chronic phase (6–19 months)	E: CSE and aquatic CSE (30 min) + conventional physical therapy (30 min) C: conventional physical therapy (30 min × 2 sessions)	20 sessions, 30 min/day, 5 days/week, 4 weeks	Greater improvement in TIS, PASS-3l, BBS-3l, FRT MBI than control (P < 0.05)
Van Criekinge et al. (2020) 87)	CSE	SB, RCT	III	39 (29/10)	Subacute phase (23–95 days)	E: CSE on both stable and unstable surfaces (60 min) + conventional physical therapy (60 min) C: cognitive training (60 min) + conventional physical therapy (60 min)	16 sessions, 60 min/day, 4 days/week, 4 weeks	Greater improvement in TIS (total, subscales of dynamic and coordination), Tinetti POMA (total, subscale of gait), gait parameters (step length and width, speed), COM displacements, active ROM of thorax and pelvis than control (P < 0.05)
Cho et al. (2020) 88)	CSE with elastic taping	SB, RCT	III	28 (15/13)	Chronic phase (6–24 months)	E: CSE + elastic taping on both sides paraspinal muscles (18 h) C: CSE + non-elastic taping (18 h)	24 sessions, 18 h/day, 3 days/week, 8 weeks	Greater improvement in dynamic COP displacement than control (P < 0.05)
Kim et al. (2022) 89)	Robot-assisted CSE	SB, RCT	III	40 (19/21)	Not stated	E: CSE assisted by robotic arm to support the forward, backward, lateral, and rotational movements of the torso (15 min) C: stretching exercise (15 min)	40 sessions, 15 min/day, 5 days/week, 8 weeks	Greater improvement in TIS, total COP displacement, LOS, BBS, FRT than control (P < 0.05)
Salgueiro et al. (2022) 23)	Tele-CSE	RCT	III	30 (20/10)	Chronic phase (> 6 months)	E: home-based CSE with online system (60 min) C: conventional physical therapy (60 min)	24 sessions, 60 min/day, 2 days/week, 12 weeks	Greater improvement in TIS (total, subscale of balance) than control (P < 0.05)
Jung et al. (2022) 90)	CSE with elastic taping	SB, RCT	III	60 (34/26)	Chronic phase (6–12 months)	E1: CSE + taping to the lateral and posterior pelvic tilt E2: CSE + taping to the posterior pelvic tilt C: CSE	30 sessions, 30 min/day, 5 days/week, 6 weeks	Greater improvement in abductor muscle strength, lateral pelvic tilt angle in E1 than E2 and control (P < 0.05) Greater improvement in 10MWT, anterior pelvic tilt angle in E1 and E2 than control (P < 0.05) with no difference between E1 and E2
Weight-shifting exercise (WSE)
Muckl and Mehrholz (2014) 28)	WSE with external or internal focus of attention	RCT	III	20 (14/6)	Subacute phase (36–71 days)	External focus group: lateralward WSE with focus on a visual target 20 cm lateral to the non-paralyzed side Internal focus group: attentional focus on a body part without any visual target	Not stated	Greater improvement in lateral weight shift in external focus group than in internal focus group (P < 0.05) No difference in anterior–posterior weight transfer between both groups
Fujino et al. (2016) 91)	WSE on tilted surface	SB, RCT	III	30 (20/10)	Acute phase (1–2 weeks)	E: move trunk laterally without leg support on surface tilted 10° to paralyzed side with vertical cord front of the wall as a visual cue + conventional physical therapy (60 min) C: trunk tilted laterally from paralyzed side to non-paralyzed side + conventional physical therapy (60 min)	6 sessions, 60 times/session, 6 days/week, 1 week	Greater improvement in TCT, lateral trunk movement capacity to non-paralyzed side than control (P < 0.05) No difference in SIAS and lateral trunk movement capacity to paralyzed side between both groups
Fukata et al. (2019) 27)	WSE on tilted surface	SB, RCT	III	33 (18/15)	Acute phase (8–23 days)	E: move trunk forward to non-paralyzed side on device (tilt angle 10° backward to paralyzed side) while looking at vertical index (10–15 min) C: move trunk forward to non-paralyzed side on horizontal plane (10–15 min) All participants: conventional physical therapy (60 min)	7 sessions, 10–15 min/day, 40 trials/session, 8 days	Greater improvement in TIS (total, subscale of static), FIST (total, subscales of static, dynamic, scooting, response), SPV (tilt direction) than control (P < 0.05) No difference in SPV (variability) between both groups
Sheehy et al. (2020) 92)	WSE with VR	SB, RCT	III	69 (46/23)	Acute and subacute phases (10–173 days)	E: tilt trunk and reach hands with VR (30–40 min) C: VR fixed to minimize trunk movement (30–40 min) All participants: conventional physical therapy	10–12 sessions, 30–40 min/day, 5 days/week, 2–3 weeks	Improvements in FIST, OSS, RPS, WMFT in post and 1-month post-intervention compared with pre-intervention (P < 0.05) No difference in outcomes between WSE group and control
Jung et al. (2021) 93)	WSE using the Space Balance 3D system	SB, RCT	III	24	Subacute phase (2–3 weeks)	E: weight transfer in the sagittal, frontal and transverse planes according to the tasks displayed on the monitor C: CSE (30 min) conventional physical therapy	15 sessions, 30 min/day, 5 days/week, 3 weeks	Greater improvement in TIS, trunk muscle strength (flexion and extension), BBA, balance posture ratio score than control (P < 0.05)
Unstable surface training
Jung et al. (2014) 94)	Unstable surface training with WSE	SB, RCT	III	17 (12/5)	Chronic phase (6–26 months)	E: WSE on unstable surface of balance pad and dynamic ball cushion (30 min) C: conventional physical therapy (30 min)	20 sessions, 30 min/day, 5 days/week, 4 weeks	Greater improvement in TRE, TIS, TUG than control (P < 0.05) No difference in TIS subscales of static and coordination between both groups
Karthikbabu et al. (2018) 95)	Unstable surface training (Swiss ball)	SB, RCT	III	108 (65/43)	Chronic phase (6–27 months)	E: selective upper and lower trunk movements in supine and sitting position with stable or unstable surface (45 min) C: conventional physical therapy (45 min) All participants: including obstacle-course gait training (15 min)	18 sessions, 45 min/day, 3 days/week, 6 weeks	Greater improvement in TIS, BBA, Tinetti scale, 10MWT, SIS-16 in stable and unstable surface group than control from baseline to 6 weeks post intervention and 3-month follow-up (P < 0.05) No difference in outcomes between stable group and unstable surface group
Shin (2020) 96)	Unstable surface training with WSE	SB, RCT	III	24 (5/19)	Chronic phase (6–28 months)	E: trunk control task by a smartphone application with visual feedback information (20 min) + conventional physical therapy (80 min) C: conventional physical therapy (80 min)	12 sessions, 20 min/day, 3 days/week, 4 weeks	Greater improvement in TIS, static balance parameter (eyes close and open), mFRT, TUG than control (P < 0.05)
Lee et al. (2020) 32)	Unstable surface training	SB, RCT	III	35 (12/23)	Subacute phase (4–10 weeks)	E: CSE with hook-lying and sitting on unstable surface (30 min) C: upper limb ROM exercises at comfortable speeds in a well-supported sitting position (30 min)	12 sessions, 30 min/day, 2 days/week, 6 weeks	Greater improvement in TIS, arm raising speed in sitting position without foot support, 6MWT than control (P < 0.05)
Thijs et al. (2021) 97)	Unstable surface training	DB, RCT	III	29 (17/12)	Chronic phase (≥ 6 months)	E: WSE, reaching, trunk lateral bending, pelvic tilt balance training with visual feedback while sitting on unstable surface (60 min) + conventional physical therapy (30–120 min) C: conventional physical therapy (30–120 min)	12 sessions, 60 min/day, 3–4 days/week, 4 weeks	Greater improvement in TIS, 10MWT (maximum speed), BBS than control (P < 0.05) No difference in 10MWT (comfortable speed), 2 Minute Walk Test, FMLE, FIM, BI between both groups
Karthikbabu et al. (2022) 82)	Unstable surface training	SB, RCT	III	84 (47/37)	Chronic phase (6–29 months)	E1: sitting balance training on unstable surface (45 min) C1: sitting balance training on stable surface (45 min) C2: conventional physical therapy (45 min) All participants: gait training including obstacle-course walking (15 min)	18 sessions, 45 min/day, 3 days/week, 6 weeks	Greater improvement in TIS, strength, weight-bearing asymmetry, ABC score in E1 and C1 groups than in C2 group from baseline to post-training and 12-month follow-up (P < 0.001) No difference in TIS, strength, weight-bearing asymmetry to paralyzed side, ABC score between both groups
Aphiphaksakul and Siriphorm (2022) 98)	Unstable surface training (balance disc)	SB, RCT	III	32 (28/4)	Subacute phase (16–64 days)	E: sitting balance program using balance disc with smartphone inclinometer application (30 min) + conventional home rehabilitation (30 min) C: conventional home rehabilitation (60 min)	20 sessions, 30 min/day, 5 days/week, 4 weeks	Greater improvement in PASS changing posture, BI than control (P < 0.05) No difference in FIST, PASS (total, subscale of maintaining posture) between both groups
Yeo et al. (2023) 99)	Unstable surface training with visual feedback	SB, RCT	III	39 (27/12)	Chronic phase (9–22 months)	E1: balance training on unstable surface with visual feedback (20 min) E2: balance training on unstable surface (20 min) C: conventional home rehabilitation (30 min)	12 sessions, 20 min/day, 3 days/week, 4 weeks	Greater improvement in TIS, BBS, TUG, gait parameter (hip flexion, knee flexion) in E1 than in E2 and control (P < 0.001) Greater improvement in TIS, BBS, gait parameter (hip and knee flexion, speed and stride length) in E1 and E2 than control (P < 0.05) No difference in gait parameters (cadence, stride time, hip extension, knee extension) between E1 and E2
Transcutaneous electrical stimulation (TES)
Chan et al. (2015) 100)	TES + CSE	DB, RCT	III	37 (29/8)	Chronic phase (6–73 months)	E: TES + CSE (60 min) [TES parameters: frequency 100 Hz, pulse width 200 μs, intensity twice the sensory threshold which below is the motor threshold, electrodes on the latissimus dorsi and EO muscles] C1: Placebo-TES + CSE (60 min) C2: not active training	30 sessions, 60 min/day, 5 days/week, 6 weeks	Greater improvement in TIS, reach distance, isometric peak trunk flexion, and extension torque in E and C1 than in C2 (P < 0.05) No difference in TIS after 6 weeks between E and C1, but greater improvement in TIS after 3 weeks in E than in C1 and C2 (P < 0.05) Greater improvement in TIS coordination score in TES group than in placebo TES and control groups (P < 0.05)
Jung et al. (2016) 38)	TES + WSE on unstable surface	DB, RCT	III	60 (36/24)	Subacute phase (3–6 months)	E: TES + WSE on unstable surface (30 min) [TES parameters: frequency 100 Hz, pulse width 200 μs, intensity 2–3 times the sensory threshold, electrodes on the ES and EO muscles] C1: Placebo-TES + WSE on unstable surface (30 min) C2: stretching exercise and stationary bicycle exercise (30 min) All participants: conventional physical therapy (60 min)	30 sessions, 30 min/day, 5 days/week, 6 weeks	Greater improvement in TIS (total, subscales of coordination), maximum reach distance, EO muscle activity during weight shift in E group than in C1 and C2 groups (P < 0.05) No difference in ES muscle activity during weight shift between E and C1 groups
Bilek et al. (2020) 35)	TES	DB, RCT	III	60	Subacute phase (> 3 months)	E: TES (20 min) + conventional physical therapy (45 min) [TES parameters: frequency 50 Hz, pulse width 400 μs, intensity maximum level in which patients felt muscle contraction without pain or discomfort, electrodes on thoracal and lumbar ES muscles bilaterally] C: conventional physical therapy (45 min)	30 sessions, 20 min/day, 5 days/week, 6 weeks	Greater improvement in PASS, STREAM than control (P < 0.05) No difference in BBA, APECS, SF-36, FAC between both groups
Yada and Amimoto (2023) 39)	TES + CSE	DB, RCT	III	26 (16/10)	Acute and subacute phase (4–54 days)	E: TES + CSE (20 min) [TES parameters: frequency 100 Hz, pulse width 200 μs, intensity 1.2–2 times the sensory threshold, electrodes on middle part of sternocleidomastoid and trapezius muscles, 3 and 1 cm lateral to L2 and L5 vertebrae] C: Placebo-TES + CSE (20 min)	1 session, 20 min/day	Greater improvement in trunk angle (non-paralyzed-side tilt) of online effect and after-effect when compared with baseline No difference in neck angle between both groups
Noninvasive brain stimulation (NIBS)
Saeys et al. (2015) 101)	tDCS	DB, RCT, Crossover design	III	31 (26/5)	Subacute phase (16–74 days)	E1: tDCS to sham stimulation E2: sham stimulation to tDCS tDCS parameters for E1 and E2: intensity of 1.5 mA, electrodes placed on the motor cortex (C3-C4 of the International EEG 10-20 system), anode on affected side and cathode on unaffected side All participants: conventional physical therapy and occupational therapy (60 min × 5 days)	16 sessions, 20 min/day, 4 days/week, 4 × 2 weeks	No difference in Tinetti, RMA, TIS between both groups in post test (after 8 weeks) Greater improvement in Tinetti, RMA (leg-trunk) at middle test (after 4 weeks) in E1 group than in E2 group (P < 0.05)
Liao et al. (2021) 49)	iTBS	DB, RCT	III	30 (15/15)	Subacute phase (25–132 days)	E: iTBS to cerebellar hemisphere on contralateral side to affected cerebral hemisphere before physical therapy (50 min) [iTBS parameters: intensity 80% of AMT, 600 stimuli for each stimulation session, target area 3 cm lateral to midline and 1 cm below the inion over the contralesional lateral cerebellum] C: sham stimulation All participants: conventional physical therapy	10 sessions, 50 min/day, 5 days/week, 2 weeks	Greater improvement in TIS, BBS at 2 weeks post test than control (P < 0.05) No difference in FMLE, BI, RMT, CSP, MEP between both groups
Tedla et al. (2022) 60)	tDCS with PNF	DB, RCT	III	54 (44/10)	Subacute phase (60–84 days)	E: tDCS of both hemispherical motor cortices (20 min), followed by trunk-target PNF (30 min) + conventional physical therapy (40 min) [tDCS parameters: intensity 2 mA, ramp-up and ramp-down 30 s, electrodes placed on motor cortex (C3-C4 of the International EEG 10-20 system), anode placed on affected side and cathode on unaffected side] C1: sham stimulation of both hemispherical motor cortices (20 min), followed by trunk-target PNF (30 min) + conventional physical therapy (40 min) C2: conventional physical therapy (90 min)	24 sessions, 20 min/day, 4 days/week, 6 weeks	Greater improvement in TIS, FMUE, WMFT, SSQOL than in C1 and C2 groups (P < 0.01) No difference in 10MWT between E and C1 groups
Whole body vibration (WBV)
Choi et al. (2014) 102)	WBV	RCT	III	30	Chronic phase (6–19 months)	E: TOT with sitting position + WBV (15 min) [WBV parameters: frequency 15–22 Hz, amplitude 0–5.8 mm] C: TOT with sitting position (15 min)	20 sessions, 15 min/day, 5 days/week, 4 weeks	Greater improvement in mFRT than control (P < 0.05) No difference in average velocity and total path length of COP between both groups
Lee et al. (2017) 64)	WBV	SB, RCT	III	30 (17/13)	Subacute phase (1–2 months)	E: sitting with WBV (30 min) + conventional physiotherapy (30 min) [WBV parameters: frequency vibrator 40 Hz] C: conventional physical therapy (30 min × 2 sessions)	10 sessions, 30 min/day, 5 days/week, 2 weeks	No difference in TIS, BBS, FAC, mBI between both groups Both groups showed improvements in TIS (total, subscales of static and dynamic), BBS, FAC, mBI of post test
Other interventions
Kılınc et al. (2016) 103)	Neurodevelopmental treatment-based trunk exercises	SB, RCT	III	22 (11/11)	Subacute phase (< 6 months)	E: trunk exercise (stretch and strength, rotation and stability training, reaching) according to neurodevelopmental treatment (60 min) C: conventional physical therapy (60 min)	36 sessions, 60 min/day, 3 days/week, 12 weeks	Both groups showed improvements in TIS, STREAM, TUG Greater improvement in BBT, FRT, 10MWT than control (P < 0.05) No difference in outcomes between both groups pre–post test
Dell’Uomo et al. (2017) 104)	Scapulohumeral rehabilitation	RCT	III	28	Subacute phase (< 6 months)	E: Proprioceptive stimulation, passive mobilization of scapula, task-directed movement of shoulder in open and closed kinetic chains, stability and dynamic movement of scapula (20 min) C: non-specific arm and trunk rehabilitation (20 min) All participants: neurorehabilitation (40 min × 2 sessions/day)	30 sessions, 20 min/day, 5 days/week, 6 weeks	Greater improvement in TIS, TCT, sitting balance test, BI than control (P < 0.05)
Ahmed et al. (2021) 105)	High-intensity training, three-dimensional training, dual-task practice	SB, RCT	III	84 (51/33)	Subacute and chronic phase (3–12 months)	E: three additional therapeutic strategies of high intensity, three-dimensional, dual-task practice (45 min) C: conventional physical therapy (45 min)	60 sessions, 45 min/day, 5 days/week, 3 months	Greater improvement in TIS (total, subscales of dynamic and coordination), BBS, 10MWT, TUG, TUG cognitive, SIS-16 than control (P < 0.001)
Bharti et al. (2022) 106)	Arm and leg cycle ergometer	RCT	III	34 (21/13)	Acute phase (7–28 days)	E: arm and leg cycle ergometer (active–passive motor) + conventional physical therapy (50 min) C: conventional physical therapy (50 min)	14 sessions, 50 min × 2/day, 7 days	Greater improvement in TCT, PASS, POMA, MI than control (P < 0.001)
Kerdsawatmongkon et al. (2023) 107)	Home-based boxing training	RCT	III	18 (15/3)	Chronic phase (6–42 months)	E: boxing training (25 min) + CSE and reach training (15 min) C: CSE and reach training (40 min)	18 sessions, 25 min/day, 3 days/week, 6 months	No difference in TIS, Mini-BESTest, ABC scale, PACES between both groups
Choi et al. (2023) 108)	Lumbar joint mobilization	RCT	III	30 (23/7)	Chronic phase (14–20 months)	E: lumbar joint mobilization (15 min) + conventional physical therapy (60 min) C: sham stimulus (15 min) + conventional physical therapy (60 min)	30 sessions, 15 min/day, 5 days/week, 6 weeks	Greater improvement in TIS (total, subscale of coordination), BBS, weight distribution, TUG, 10MWT (step and stride) than control (P < 0.05) No difference in FGA between both groups

ABC: Activities-specific Balance Confidence, AMT: active motor threshold, APECS: Adapted Patient Evaluation and Conference System, BBA: Brunel Balance Assessment, BBS: Berg Balance Scale, BBS-3l: Berg Balance Scale 7 items-3 level, BI: Barthel Index, Brief-BESTest: Balance Evaluation Systems Test-brief version, C: control group, C1: group receiving one control intervention, C2: group receiving another control intervention, COM: center of mass, CSE: core-stability exercise, CSP: cortical silent period, DB: double-blind, E: experimental group receiving target intervention, E1: group receiving target intervention at first in a crossover study, E2: group receiving target intervention for second time in a crossover study, EO: external oblique, ES: erector spinae, FAC: Functional Ambulation Categories, FGA: Functional Gait Assessment, FIM: Functional Independence Measure, FIST: Function In Sitting Test, FMLE: Fugl-Meyer Lower Extremity Assessment, FMUE: Fugl-Meyer Upper Extremity Assessment, FRT: Functional Reach Test, H: hemorrhage, I: ischemia, iTBS: intermittent theta-burst stimulation, LOS: limits of stability, mBI: modified Barthel Index, MEP: motor-evoked potential, mFRT: modified Functional Reaching Test, MI: Motricity Index, Mini-BESTest: Mini-Balance Evaluation Systems Test, OSS: Ottawa Sitting Scale, PACES: Physical Activity Enjoyment Scale, PASS: Postural Assessment Scale for Stroke, PASS-3l: Postural Assessment Scale for Stroke 5 item-3 level, PNF: proprioceptive neuromuscular facilitation, POMA: Performance Oriented Mobility Assessment, RCT: randomized controlled trial, RMA: Rivermead Motor Assessment, RMT: resting motor threshold, ROM: range of motion, RPS: Reaching Performance Scale, SB: single-blind, SF-36: Short Form-36, SIAS: Stroke Impairment Assessment Set, SIS-16: Stroke Impact Scale-16, SPV: subjective postural vertical, SSQOL: Stroke Specific Quality Of Life, STREAM: Stroke Rehabilitation Assessment of Movement, TCT: Trunk Control Test, tDCS: transcranial direct current stimulation, TES: transcutaneous electrical stimulation, TIS: Trunk Impairment Scale, TOT: task-oriented training, TRE: trunk reposition error, TUG: Timed Up-and-Go Test, VR: virtual reality, WBV: whole body vibration, WMFT: Wolf Motor Function Test, WSE: weight-shifting exercise, 6MWT: 6-min Walk Test, 10MWT: 10-meter Walk Test.

Core-stability exercise

Core-stability exercise (CSE) includes lumbar and pelvic exercises designed to directly activate core muscles and improve motor performance and postural stability. It includes pelvic tilt, upper trunk rotation, trunk tilt, and reach movements in the supine, seated, and standing positions, as well as a back bridge in the supine position. This method restores trunk control and significantly improves balance and gait.¹⁹⁾ Gamble et al.²⁰⁾ reported that CSE, in addition to conventional rehabilitation, can improve trunk control, dynamic balance, and gait speed in patients with stroke more than conventional rehabilitation alone.

Cabanas-Valdes et al.²¹⁾ reported on the effects of CSE in patients with subacute stroke. Patients who received 15 min of CSE daily, in addition to physical therapy 5 days/week for 5 weeks, showed a significant improvement in balance function and ADL compared with physical therapy alone. The mean age of the patients was 75.3 years (standard deviation 10.0 years), and some could not maintain a sitting posture. Therefore, CSE combined with conventional physical therapy may be effective in older patients with severely impaired trunk control.²¹⁾

CSE is a structured step-by-step approach that is considered an effective rehabilitation treatment for various neurological diseases. Combining CSE with conventional physical therapy is suitable for patients with trunk control impairments following stroke.

CSE by telerehabilitation

Recently, telerehabilitation has become widely prevalent. Therapists instruct and follow up patients at home using online telecommunications equipment. It has the benefit of reducing costs related to patient assistance and travel and contributes to equalizing regional disparities in healthcare.²²⁾ In addition, CSE requires long-term training sessions lasting more than 4 weeks.⁸⁾ Therefore, CSE performed at home through telerehabilitation is beneficial for patients following stroke, and its effects have been investigated.

Salgueiro et al.²³⁾ reported the effects of a CSE intervention based on a smartphone application in patients with chronic stroke. The intervention group performed ten repetitions of each of the 32 exercises according to the program. Considering the participants’ fatigue levels, they were recommended to perform as many exercises as possible with breaks. A 1-h session was performed twice weekly for 12 weeks. The telerehabilitation group showed a significantly greater improvement in trunk control evaluated using the TIS than the control group. However, their adherence was relatively low, and 9 of the 13 patients dropped out of the study.²³⁾ To improve adherence, it would be better to limit the number of training sessions with shorter therapeutic exercise programs.

New technologies are constantly integrated into our daily lives, which may help to reduce patient resistance to telerehabilitation. Telerehabilitation will become more widespread in the future, and appropriate validation will be required to establish its effects.

Weight-shifting exercise

In trunk control intervention, weight-shifting exercise (WSE) involves repetitive reaching movements in the anterior and lateral directions while seated. The level of difficulty can be adjusted based on the repetition time, reaching distance, destabilized seat setting, and sitting posture. WSE is effective in improving balance and reaching movements not only in sitting but also in standing positions.²⁴⁾

Masani et al.²⁵⁾ examined the response of trunk muscles to multidirectional trunk tilting in a sitting position in healthy individuals. Inclining the trunk forward activated the erector spinae muscle and inclining it toward the right side activated the left oblique abdominal muscle. Meanwhile, inclining the trunk in the oblique direction activated both the erector spinae and oblique abdominal muscles on the contralateral side to the tilt direction. Oblique trunk training may be more feasible than trunk training in one simple direction for enhancing the core muscles.²⁶⁾

Fukata et al.²⁷⁾ reported that the group seated on a device tilted 10° diagonally backward toward the affected side, while leaning the trunk diagonally forward to the unaffected side using the vertical index as a visual cue for tilt, showed significantly greater improvement in TIS, FIST, and subjective postural vertical (SPV) than the control group seated on a flat plane and performing the same training. This study included participants with low static sub-scores on the TIS, suggesting that it is effective even in patients with low sitting ability. The improvement in SPV may have been caused by an increased gravity perception, enhanced by the inclination of the seat surface and the vertical cue, thereby facilitating visual and somatosensory transformations.²⁷⁾

Mückel and Mehrholz²⁸⁾ reported that an external focus of attention is more effective for weight-shift control than an internal focus. The combination of an inclined seat surface and external focus may be effective in improving trunk control ability and verticality in patients following stroke.

Unstable surface training

Sitting on an unstable surface requires prolonged enhancement of muscle activity related to posture maintenance in healthy adults.²⁹⁾ Instability in various directions on an unstable surface induces different patterns of intermuscular coordination by altering the activation ratio of agonist and antagonist muscles.³⁰⁾ Therefore, trunk training on an unstable seating surface is more useful than training on a stable seating surface in patients following stroke.³¹⁾

In a study of stroke patients in the subacute phase, Lee et al.³²⁾ reported the benefits of trunk training using the unstable surface of exercise balls (BOSU^® and Swiss balls) in hook-lying or seated positions twice a week for 6 weeks. In comparison with a control group that performed upper limb exercises while seated on a stable surface, they found that use of the unstable surface improved TIS, decreased sway area in the sitting position without foot support, increased velocity to raise a non-paralytic upper limb, and increased walking speed.

Training combined with transcutaneous electrical stimulation

Transcutaneous electrical stimulation (TES) includes neuromuscular electrical stimulation (NMES) and transcutaneous electrical sensory nerve stimulation (TESS). NMES stimulates peripheral motor nerves and muscles, effectively preventing muscle atrophy, decreasing spasticity, increasing muscle strength, and improving functional movement.³³⁾ NMES is commonly used to promote muscle contraction in the upper and lower limbs after stroke.³⁴⁾ However, few reports exist on NMES for trunk muscles.

Bilek et al.³⁵⁾ reported that NMES of the erector spinae for 20 min/day combined with conventional rehabilitation therapy for 5 days/week for 6 weeks showed greater improvement in the Postural Assessment Scale for Stroke (PASS) and Stroke Rehabilitation Assessment of Movement (STREAM) than therapy alone. In this study, conventional rehabilitation therapy included neurodevelopmental facilitation techniques, passive mobilization, postural control therapy, stretching and range of motion (ROM) exercises, balance training, and occupational therapy. NMES combined with therapy may have beneficial effects not only in improving trunk control function but also in improving paralytic limb motion.³⁵⁾

TESS is an electrical stimulation of the peripheral sensory nerves at an intensity equal to the sensory threshold without muscle contraction. It compensates for sensory inputs, induces long-term neuroplastic changes, and enhances motor recovery in patients following stroke.^36,37) Jung et al.³⁸⁾ reported that TESS of the erector spinae and external oblique muscles combined with a seated weight transfer task for 30 min/day, 5 days/week for 6 weeks, showed a significant increase in activation of the external oblique muscles during weight transfer, maximum reach distance of the upper limb in a seated position, and improved TIS score.

Recently, Yada and Amimoto³⁹⁾ combined TESS and CSE for 20 min to treat back and neck muscles in patients following stroke. A single intervention improved the trunk tilt angle to the non-paralyzed side during weight transfer. However, they did not evaluate trunk functions, such as TIS score and maximum reach distance.

Overall, the combination of TES with rehabilitation therapy can potentially improve trunk control more effectively than rehabilitation therapy alone. However, the stimulation sites and parameters used in the studies reported to date have varied. Therefore, the effects of these variations should be determined by further investigations using a standardized method.

Training combined with NIBS

NIBS has become an important neurorehabilitation option, employing a neuromodulation technique that alters the excitability of neuronal cells and promotes neuroplasticity by applying magnetic and electrical stimulation above the cranium.⁴⁰⁾ NIBS combined with rehabilitation therapy is a strategy used to facilitate recovery from post-stroke functional impairments caused by an imbalance of neuronal excitability.^41,42,43,44) Several types of NIBS have been developed, including TMS and tDCS, which are frequently used in clinical rehabilitation settings.

Transcranial magnetic stimulation

TMS is a NIBS method involving the generation of a pulsed magnetic field by an electric current flowing through a coil (5–10 cm in diameter) that is applied to the scalp, thereby generating eddy currents in the brain tissue and exciting neurons.⁴⁵⁾ Repetitive TMS (rTMS) can induce neuroplasticity depending on the stimulus frequency. A combination of rTMS and rehabilitation therapy can induce functional recovery from motor paralysis by inducing task-specific plasticity in patients following stroke.^46,47,48)

Regarding rTMS effects on trunk control, Liao et al.⁴⁹⁾ reported the effects of intermittent theta-burst stimulation (iTBS) applied to the cerebellar hemisphere on the contralateral side to the affected cerebral hemisphere immediately before physical therapy. Physical therapy included trunk control, standing, balance, and gait training for 50 min/day, 5 days/week for 2 weeks. The combination of iTBS with physical therapy showed greater improvement in the TIS and Berg Balance Scale (BBS) scores than therapy alone.⁴⁹⁾ This suggested that iTBS enhanced cerebellar activity on the intact side by inducing long-term potentiation and enhancing cerebellar functions related to trunk control and balance.

Transcranial direct current stimulation

tDCS is a NIBS method that can alter cortical excitability by continuously applying a weak direct current of 1–2 mA over the scalp.^50,51) It is an inexpensive, safe, and relatively easy-to-use stimulation method to treat neurological dysfunction by combining rehabilitation therapy in patients with various CNS disorders.^{51,52,53,54,55)} The effects of tDCS depend on electrical current density (current intensity/electrode size), stimulation time, site, and polarity. Generally, anodal tDCS increases neuronal excitability in the stimulated area by changing the membrane potential in a depolarized direction. Conversely, cathodal tDCS decreases neuronal excitability by hyperpolarizing the membrane potential.⁵⁶⁾ Long-term effects of tDCS are related to the release of neurotransmitters, sensitivity changes in N-methyl-D-aspartate receptors,⁵⁷⁾ and the regulation of extracellular potassium concentration by astrocytes.⁵⁸⁾ Although tDCS combined with rehabilitation therapy is reported to improve upper-limb function and ADL,⁵⁹⁾ there are only a few reports of treatments targeting trunk control impairment in patients following stroke.

Tedla et al.⁶⁰⁾ reported that 20 min of tDCS followed by 30 min of trunk-targeted proprioceptive neuromuscular facilitation (PNF) and 40 min of conventional physical therapy significantly improved TIS score when compared with PNF and physical therapy alone. In this study, physical therapy included stretching stiff muscles, strengthening muscle exercises, bridging, rolling, weight-bearing on the affected side, weight-shifting, ROM exercises, and gait training. In addition, significant improvements were observed in the pre–post mean differences in the Fugl–Meyer Upper Extremity Assessment, Wolf Motor Function Test, and stroke-specific QOL in the tDCS group, suggesting that tDCS effects could extend to upper limb function and lead to improved QOL.⁶⁰⁾ Although the combination of NIBS with trunk control training may be effective, the most appropriate parameters regarding stimulation sites, intensity, and inclusion criteria for patients should be clarified in the future.

Whole body vibration

WBV uses a platform capable of providing mechanical vibrations to the entire body at various frequencies and magnitudes. Recent reports have shown that it improved muscle strength and postural control in healthy individuals and patients with various diseases.⁶¹⁾ WBV is believed to affect postural control by activating the group Ia and II afferents in muscle groups, activating motor units, modulating the excitability of the spinal motor neuron pool, and improving proprioception.^62,63)

Lee et al.⁶⁴⁾ reported that WBV in the sitting position, in addition to conventional physical therapy, showed no further effects than the use of therapy alone in patients following stroke. Physical therapy improves TIS, BBS, gait function, and ADL. Although no effect of WBV on trunk control impairment was observed, the number of reports is limited. Therefore, further investigations of this intervention will require the use of larger patient cohorts.

Cerebellar Ataxia

Cerebellar ataxia includes limb and trunk ataxia. The instability of the trunk secondarily leads to difficulties in smooth limb movements.⁶⁵⁾ For example, trunk instability in the sitting position can cause swaying of the upper limbs, resulting in unstable reaching. Therefore, trunk ataxia affects overall ADL in sitting and standing, in addition to walking dysfunction. The following discussion summarizes the findings of studies that have demonstrated the effectiveness of trunk control training in patients with ataxia (Table 2).

Table 2. Characteristics of primary research on impaired trunk control in cerebellar ataxia

Authors (year)	Intervention	Study design	Class	n	Diagnosis, age	Procedure	Frequency	Result
Task oriented training (TOT) for balance function
Ali et al. (2021) 68)	TOT	SB, RCT	III	45	Multiple sclerosis (20–45 years)	E: TOT on unstable surface (25 min) + conventional physical therapy (25 min) C1: CSE (25 min) + conventional physical therapy (25 min) C2: conventional physical therapy (50 min)	12 sessions, 25 min/day, 2 days/week, 6 weeks	Greater improvement in SI, APSI, MLSI, BBS in E and C1 groups than in C2 group (P < 0.05) Greater improvement in APSI, MLSI than in C1 group (P < 0.05)
Doğan (2023) 69)	TOT using VR	SB, RCT	III	32	Multiple sclerosis (18–55 years)	E: seven computer games that imitate daily tasks to provide unilateral and bilateral upper limb training (60 min) C: Tele-balance training using home-based exercise program (balance, strengthening, coordination, stretching exercise) (60 min)	24 sessions, 60 min/day, 3 days/week, 8 weeks	Both groups showed improvements in TIS, ICARS, Minnesota test (P < 0.05) Greater improvement in TIS (subscale: dynamic), ICARS than in tele-balance group (P < 0.05)
Core-stability exercise (CSE)
Yigit et al. (2022) 70)	Functional CSE	RCT	III	20	Autosomal recessive hereditary ataxia (5–18 years)	E: routine CSE (45 min) for 2 days/week and functional CSE (45 min) 1 day/week C: routine CSE (45 min) for 3 days/week	24 sessions, 45 min/day, 3 days/week, 8 weeks	Greater improvement in mFRT AP and ML measurements than control (P < 0.05) No difference in ICARS, TIS, NHPT, Q-DASH between both groups
Elshafey et al. (2022) 109)	CSE	SB, RCT	III	36	Cerebellar ataxic cerebral palsy (5–9 years)	E: CSE (30 min) + conventional physical therapy (60 min) C: conventional physical therapy (60 min)	24 sessions, 30 min/day, 3 days/week, 8 weeks	Greater improvement in SARA, BESS, BOT-2, HUMAC balance system scoring than control (P < 0.05)
Whole body vibration (WBV)
Ayvat et al. (2021) 72)	WBV	SB, RCT, crossover design	III	20	Cerebellar ataxia (13 multiple sclerosis, 7 spinocerebellar ataxia) (26–40 years)	E: WBV + conventional physical therapy (60 min) [WBV parameter and posture: vibrator frequency 30 Hz, 4 sets (1 min WBV during slight squat position and 1 min rest per set)] C: conventional physical therapy (60 min)	12 sessions, 60 min/day, 3 days/week, 8 × 2 weeks	Improvements in SOT, ICARS, BBS in both programs (P < 0.05) Greater improvement in SOT, ICARS, BBS than control (P < 0.05)
Other interventions
Barbuto et al. (2021) 110)	Balance training	SB, RCT	III	14	Degenerative cerebellar disease (20–70 years)	E: three levels of balance training (sitting on stable to unstable surfaces, standing on stable to unstable surfaces, walking) (30 min) C: bike exercise with home training (30 min)	20 sessions, 30 min/day, 5 days/week, 4 weeks	Both groups showed improvements in TUG, DGI, walking speed, SARA (P < 0.05) Greater improvement in SARA, VO2max in control group than in E group (P < 0.05)

AP: anterior–posterior, APSI: Anterior Posterior Stability Index, BBS: Berg Balance Scale, BESS: Balance Error Scoring Systems, BOT-2: Bruininks-Oseretsky Test of Motor Proficiency, C: control group, C1: group receiving one control intervention, C2: group receiving another control intervention, CSE: core-stability exercise, DGI: Dynamic Gait Index, E: experimental group, ICARS: International Cooperative Ataxia Rating Scale, mFRT: modified Functional Reach Test, ML: medial–lateral, MLSI: Medio Lateral Stability Index, NHPT: Nine-hole Peg Test, Q-DASH: Quick Disabilities of Arm Shoulder and Hand, RCT: randomized controlled trial, SARA: Scale for Assessment and Rating of Ataxia, SB: single-blind, SI: Stability Index, SOT: Sensory Organization Test, TIS: Trunk Impairment Scale, TOT: task-oriented training, VR: virtual reality, WBV: whole body vibration.

Task-oriented training for balance function

Task-oriented training (TOT) involves specific tasks related to ADL, including sitting, standing, and walking,⁶⁶⁾ and it has achieved better motor control and ADL performance than training with tasks not oriented toward ADL.⁶⁷⁾ Ali et al.⁶⁸⁾ reported that trunk stability in the mediolateral and anteroposterior directions was improved in multiple sclerosis patients showing ataxia who received TOT for balance function more than in those who received CSE and conventional physical therapy alone. The CSE used task positions that ranged from lying down to quadruped but did not use sitting or standing positions. TOT comprised tasks such as standing and walking. This suggests that the difference in the effects was caused by greater improvement of dynamic postural control related to ADL in the TOT than in the CSE group.⁶⁸⁾

Doğan et al.⁶⁹⁾ reported that TOT using virtual reality (VR) demonstrated greater improvements in dynamic sitting balance and overall ataxic symptoms than home-based exercise using telerehabilitation in multiple sclerosis patients showing ataxia. In this study, TOT included trunk and upper limb movements, stepping, and walking. The difficulty level in the training was adjusted by increasing the complexity of the task and changing the ground, distance, speed, obstacle characteristics, and game levels. Furthermore, the items used during the exercise (small ball, hollow cup, filled cup, telephone, tray, cup-on-tray, balls with varying weights, box) were changed. Home-based exercises included balance, muscle strengthening, conditioning, and stretching. The patient-specific difficulty level of the program was adjusted by increasing the weight loads and number of repetitions and changing the floor features (hard to soft) and the support surface. The exercise intensity in both groups was similar. The results indicated that TOT using VR may have promoted the conformation of internal sensations during trunk and limb movements to the environment and more efficiently improved dynamic postural control and ataxic symptoms.⁶⁹⁾

It is recognized that TOT based on tasks that require dynamic postural control as used in daily life is effective. However, the effects of TOT have only been reported in patients with multiple sclerosis, who may have sensory and cerebellar ataxia. Therefore, investigating these effects in patients with cerebellar diseases is necessary.

Core-stability exercise

Although CSE is less effective than TOT in some aspects of trunk control and ataxic symptoms, it is expected to improve trunk control in patients with cerebellar ataxia, similar to those with stroke. CSE comprises tasks that activate the trunk muscles to improve their strength and endurance and promote neuromuscular coupling.

Yigit et al.⁷⁰⁾ reported a different effect of the combination of typical and functional CSE compared to that of typical CSE alone in children with autosomal recessive cerebellar ataxia. The typical CSE comprised strengthening exercises for trunk muscles, weight transfer in the sitting position, and balance training on an unstable surface. Functional CSE comprised more challenging reaching tasks with trunk extension. The combination significantly improved reaching distance in the anterior–posterior and medial–lateral directions in the sitting position compared with the typical CSE alone.⁷⁰⁾ Overall, trunk control function and ataxic symptoms improved with both CSE interventions without any significant differences. Functional CSE strongly improved anteroposterior and mediolateral reach distances, suggesting that the inclusion of reaching tasks requiring trunk extension improved trunk control in an unstable posture. However, there has been no report of functional CSE in adult patients with cerebellar ataxia; therefore, validation is needed for these patients.

Whole body vibration

The effectiveness of WBV has been demonstrated in patients who have had stroke, especially in specific programs aimed at postural control.⁷¹⁾ A few studies have demonstrated the effectiveness of WBV in patients with cerebellar ataxia, which impairs postural control in various ways.

Ayvat et al.⁷²⁾ reported the effects of WBV in a standing position in addition to conventional physical therapy. WBV was shown to improve overall ataxic symptoms, balance function, and the sensory systems, contributing to balance more than therapy alone in patients with cerebellar ataxia in a crossover design. Sensory systems were evaluated using the Sensory Organization Test (SOT) to examine somatosensory, visual, and vestibular sensations during standing. Notably, WBV showed additional improvements in patients with cerebellar ataxia but not in patients following stroke, suggesting that WBV improves sensory integration, which requires postural control of the cerebellum. WBV was performed in the standing position in patients with cerebellar ataxia and the sitting position in patients following stroke.⁷²⁾ A more challenging postural task during WBV may be important for improving ataxia and balance. WBV in the standing position may enhance the dynamic sensitivity of muscle spindle afferents by stretching joint ligaments,⁷³⁾ leading to improved ataxia and balance function.

Parkinson’s Disease

PD is a progressive neurodegenerative disease characterized by bradykinesia, resting tremors, rigidity, impaired postural reflexes, and associated disorders, including postural abnormalities.⁷⁴⁾ The postural control system is progressively impaired, particularly during postural responses to external stimuli.⁷⁵⁾ Severe postural abnormalities also develop owing to an abnormally hyperflexed trunk in the standing posture, known as camptocormia. A malignant cycle between camptocormia and impaired trunk control has also been reported.⁷⁶⁾ The following discussion presents our review of studies on trunk control rehabilitation in PD (Table 3).

Table 3. Characteristics of primary research on impaired trunk control in Parkinson's disease

Authors (year)	Intervention	Study design	Class	n	Hoehn and Yahr scale	Procedure	Frequency	Result
Core-stability exercise (CSE)
Hubble et al. (2019) 111)	CSE	SB, RCT	III	24	1–3	E: CSE + fall prevention education C: fall prevention education	24 sessions, education 1 day/week, exercise 1 day/week, 12 weeks	Greater improvement in standing sway area on a foam surface with eyes closed, reduced sway variability in the ML direction than control (P < 0.05)
Gandolfi et al. (2019) 78)	CSE + active self-correction exercises	SB, RCT	III	37	1–4	E: CSE (20 min) + active self-correction exercises against trunk forward flexion with visual and proprioceptive feedback (40 min) C: joint mobilization (20 min), muscle strengthening and stretching (20 min), gait and balance training (20 min)	20 sessions, 60 min/day, 2 days (self-practice 3 days)/week, 4 weeks	Greater improvement in trunk forward flexion, Mini-BESTest than control (P < 0.05) No difference in UPDRS-III, PDS in area and length, number of falls between both groups
Cabrera-Martos et al. (2020) 77)	CSE	SB, RCT	III	44	2–3	E: CSE (45 min) C: conventional physical therapy (45 min)	20 sessions, 45 min/day, 3 days/week, 8 weeks	Greater improvement in Mini-BESTest, ABC scale, LOS (forward, right, left) than control (P < 0.05)
Vasconcellos et al. (2023) 112)	Tele-CSE	SB, RCT	III	28	2–4	E: home-based CSE with education by booklets and videos C: conventional physical therapy	21 sessions, 7 days/week, 3 weeks	No difference in COP displacement, gait parameter (speed, joint angle) between both groups
Whole body vibration (WBV)
Li et al. (2021) 113)	WBV	SB, RCT	III	29	1–3	E: WBV (10 min) [WBV parameters and posture: frequency vibrator 6 Hz, amplitude 3 mm during standing] C: conventional physical therapy (10 min)	2 sessions, 10 min/day, 1 day/month, 1 month	Improvement in UPDRS-motor, FRT, TUG in both groups (P < 0.05) but no difference between groups
Rehabilitation for trunk malalignment
Arii et al. (2014) 81)	rTSMS	SB, RCT, crossover design	III	37	3–4	E: rTSMS [rTSMS parameters: average maximum field strength 1 T, 40 stimuli (5 Hz, 8 trains/s, 10-s intertrain intervals) targeting most bent segment of spine] C: sham stimulation	1 session	Greater improvement in thoracolumbar spinal flexion angle in standing and sitting than control (P < 0.05)
Morrone et al. (2016) 79)	Perceptive rehabilitation	SB, RCT	III	10	2–3	E: perceptive rehabilitation with deformable latex cones on rigid wooden board on patients’ back to correct spinal angle (45 min) C: conventional physical therapy (45 min)	10 sessions, 45 min/day, 3 days/week, 4 weeks	Greater improvement in kyphosis angle than control (P < 0.05) No difference in APSI, MLSI, FRI, gait parameters between both groups
Volpe et al. (2017) 80)	Postural rehabilitation with aquatic	SB, RCT	III	30	2–3	E: postural realignment with aquatic therapy C: postural realignment with usual therapy	40 sessions, 60 min/day, 5 days/week, 8 weeks	Greater improvement in cervical and thoracolumbar flexion, lateral inclination of trunk than control (P < 0.05) Improvements in UPDRS-III, TUG, BBS, ABC scale, FES, PDQ-39 in both groups

ABC: Activities-specific Balance Confidence, APSI: Anterior Posterior Stability Index, BBS: Berg Balance Scale, C: control group, CSE: core-stability exercise, E: experimental group, FES: Fall Efficacy Scale, FRI: Fall Risk Index, FRT: Functional Reach Test, LOS: limits of stability, Mini-BESTest: Mini-Balance Evaluation Systems Test, MLSI: Medial Lateral Stability Index, PDQ-39: Parkinson's Disease quality of life questionnaire-39 items, PDS: percentage difference of sway, RCT: randomized controlled trial, rTSMS: repetitive trans-spinal magnetic stimulation, SB: single-blind, TUG: Timed Up-and-Go Test, UPDRS-III: Unified Parkinson's Disease Rating Scale Part III, WBV: whole body vibration.

Core-stability exercise

CSE is commonly used to activate the trunk muscles and improve balance in patients with PD. Cabrera-Martos et al.⁷⁷⁾ reported that CSE graded according to individual need significantly improved balance function, self-efficacy in preventing falls, and stability compared with conventional physical therapy. CSE was based on motor learning and skill acquisition and was differentiated into three phases of difficulty. The first phase aimed to activate the deep layer of the trunk muscles using biofeedback to pressure produced by an inflatable cushion connected to a pressure gauge. The cushion was placed around the waist of a sitting patient and inflated until the waist curve straightened, at which point the target pressure was determined. Patients had to maintain the target pressure using visual feedback provided by analog gauges showing the pressure. The second phase focused on coordination between the deep and superficial layers of the trunk muscles through pelvic and limb exercises. The third phase comprised practical training in various environments and situations. Adjustment of difficulty level according to individual trunk control ability may be effective.⁷⁷⁾

Gandolfi et al.⁷⁸⁾ reported that CSE combined with graded exercises that partially used sensory feedback significantly improved hyper-forward flexion of the trunk and balance function in patients with PD compared with conventional physical therapy. Graded exercises were categorized into three levels of difficulty. The first phase comprised exercises using mirror visual feedback. The second phase comprised exercises using proprioceptive feedback from electromyographic recordings of the trunk muscles. The third phase involved exercise without sensory feedback. Physical therapy comprised ROM exercises, muscle strengthening, stretching, balance, and gait exercises. No significant differences were observed in the Unified Parkinson’s Disease Rating Scale Part III (UPDRS-III), percentage difference in sway area, length of sway, and number of falls per month between CSE and conventional therapy.⁷⁸⁾

The above findings suggest that CSE is effective not only for balance function but also for camptocormia. Adjusting the difficulty level for individual patients may also be effective. Particularly in patients with severe impairments in trunk control and deformation, lower-level tasks in the lying or sitting positions can be performed safely without the risk of falling. However, the setting of the loading dose, generalization to ADL, and durability of the effects remain unknown. Therefore, it will be necessary to investigate a larger number of patients in the future.

Rehabilitation for trunk malalignment

Many studies of PD have aimed to improve balance function by correcting postural alignment rather than by using trunk training, which is the typical treatment for stroke and cerebellar ataxia.

Perceptual task

Morrone et al.⁷⁹⁾ reported the effects of using a perceptual task designed to improve the perception of the trunk and midline using a specially constructed device (wooden board fitted with latex cones of various lengths, sizes, and elasticities). The perceptual task required the patient to lie down with their back against the device, and the patient was asked questions regarding cone location, number of cones, cone elasticity, and symmetry of the cone distribution. In addition, they performed breathing, pelvic tilting, and lower limb exercises to encourage attention to the trunk during contact with the sticks on the back. The perceptual task decreased the kyphosis angle compared with conventional physical therapy, such as lower limb joint mobilization, stretching, coordination, and balance exercises. No significant differences were observed in stability, risk of falling, or gait parameters.⁷⁹⁾

Although the perceptual task improved spinal malalignment, it did not improve postural control or balance function, possibly because the trunk control impairment in patients with PD may not be caused by sensory deficits. Therefore, perceptual tasks may have limitations in improving balance.

Aquatic postural rehabilitation

Volpe et al.⁸⁰⁾ reported that aquatic postural rehabilitation significantly improved the ROM of cervical and back flexion and the lateral trunk inclination compared with rehabilitation on the ground. The postural rehabilitation exercises aimed to improve deformities. Significant improvements were observed in the UPDRS-III, Timed Up-and-Go test, BBS, Activities-specific Balance Confidence Scale, Fall Efficacy Scale, and Parkinson’s disease quality of life questionnaire-39 (PDQ-39) items after rehabilitation both in water and on the ground. These results suggest that specific properties of water, such as higher density, reduced gravity, hydrostatic pressure, buoyancy, viscosity, and thermodynamics, can improve the limitation of neck and trunk movements. However, both aquatic and ground postural rehabilitation appear effective in improving postural control, dynamic balance, and self-efficacy to prevent falls. Aquatic rehabilitation offers the added advantage of reduced risk of falling during exercise.⁸⁰⁾

Repetitive trans-spinal magnetic stimulation

Arii et al.⁸¹⁾ reported the short-term effects of a single session of repetitive trans-spinal magnetic stimulation (rTSMS) on camptocormia. rTSMS (5 Hz, 8 train/s, 10-s intertrain intervals, 40 stimulation times in total, 1 T average maximum magnetic field strength) was applied on the most bent segment of the spine, which significantly improved the thoracolumbar flexion angle in both the sitting and standing positions compared with sham stimulation. Although the mechanism of this effect has not been proven, the authors considered that it may have blocked afferent inputs of sensory nerves, thereby enhancing descending brainstem and corticospinal motor outputs, similar to spinal cord stimulation. However, it remains unclear whether rTSMS affects trunk control.⁸¹⁾

DISCUSSION

We reviewed the methods and effectiveness of the therapeutic interventions for trunk control impairments depending on the type of the affected CNS. Although many kinds of interventions were found for stroke, fewer were observed for cerebellar ataxia and PD, suggesting that further investigation is necessary for those disorders.

Regarding motor training of the trunk, CSE was commonly adopted in all three diseases. It enhances trunk dynamic stability and upright posture alignment, as well as optimal muscle power of the trunk flexor and extensor.⁸²⁾ The difficulty level of CSE can be adjusted using several different limb positions and exercises. It was particularly effective for patients with stroke and cerebellar ataxia who showed a decrease in the trunk muscle tone. For patients with PD, it may also be effective because it can enhance central nervous function related to trunk control.⁷⁸⁾ Meanwhile, grading the training difficulty of CSE can be challenging because of the nature of the pathological condition of PD. PD is characterized by symptoms such as resting tremor, muscle rigidity, and akinesia, which can hinder smooth voluntary movements of the limbs and trunk. Therefore, it is crucial to carefully consider factors such as posture, parameters of movement (range, speed, frequency), and external stimuli (auditory stimulation, visual cues) for determining the appropriate difficulty level for CSE.

WSE and unstable surface training have been mainly used in patients with stroke. Both are based on performing tasks in a sitting position, which is different from CSE. It is applicable to patients with poor spontaneity. WSE can enable patients to easily perform a reaching task with an external target set. It has a therapeutic effect on verticality in patients with stroke. Unstable surface training increases not only voluntary activity but also the reflexive activity of trunk muscles related to postural changes and improves coordinate patterns of trunk muscle contraction timing.³⁰⁾ Similar to CSE, it is also important to adjust the seating condition, reaching direction, and difficulty level depending on individual severity.²⁷⁾

TES and NIBS are used in patients with stroke. In the acute and subacute phases of stroke, signals from the motor cortex through the corticospinal tract are impaired. TES and NIBS can change motor-related cortical excitability and promote neuroplasticity at the CNS level, resulting in improved trunk control in patients with subacute stroke.^35,38,40) In the chronic phase, trunk muscle weakness is found because of the disuse of trunk muscles and insufficient recruitment of motor units.⁸¹⁾ TES can activate residual motor neurons and improve disuse muscle atrophy,³³⁾ and it is effective in patients with chronic stroke. However, the number of reports remains small, and validation with a larger number of patients in multiple studies is necessary.

TOT for balance function reported in patients with cerebellar ataxia comprises tasks used in real-world activities. It is designed to integrate various control factors, such as muscle strength and endurance, ROM, motor coordination, sensory awareness, and postural control. It is possible to grade the difficulty levels by changing the range and direction of the movements. For example, participants were asked to repeat a movement adjusted by the level on a Swiss ball, sit on chairs at various heights, and then perform a stand-up and walking task. Ali et al.⁶⁸⁾ showed that repetitive TOT was more effective than CSE, suggesting that its effects extend into ADL. TOT may be feasible for expanding ADL in patients with trunk control impairment.

WBV in the sitting position was effective for patients with cerebellar ataxia but not for those with stroke.⁶⁴⁾ It increases sensory inputs, including group Ia and II afferents, and enhances the excitability of spinal motor neurons, leading to improved proprioception, which aids in sensing postural changes and controlling the trunk. WBV may be more effective in patients with cerebellar ataxia, who have more impaired sensory integration because of disturbed cerebellar internal models, than those with stroke.^62,63)

In patients with PD, therapeutic interventions targeted trunk malalignment such as camptocormia. Spinal deformity was improved by perceptual tasks to make patients aware of their posture by adjusting the difficulty levels. Training was aimed at alleviating a vicious cycle between trunk malalignment and trunk control impairment.⁷⁶⁾ However, trunk control, as evaluated by the Anterior–Posterior Stability Index, Medial–Lateral Stability Index, and Fall Risk Index (calculated from the center of mass displacement) did not show improvement. Furthermore, gait parameters, including walking speed and stride length, were not enhanced following the correction of trunk malalignment. In the future, more effective interventions aimed at improving trunk control will be required.

For trunk control impairments caused by CNS diseases, the first step is to understand the pathology specific to each condition. The second step is to select an appropriate intervention based on the identified pathology. In post-stroke patients, if trunk control impairments result from motor paralysis of the proximal limb and trunk, CSE or WSE combined with TES would be effective. If the impairments are caused by verticality or sensory function deficits, WSE or unstable surface training with visual, auditory, or proprioceptive feedback would be beneficial. For patients with cerebellar ataxia, practical daily activity training such as TOT would be effective in improving both trunk control and ADL. In patients with PD, CSE targeting postural muscles or interventions aimed at improving alignment and enhancing body awareness may be effective, although their impact on ADL may be limited.

This review provides evidence-based rehabilitation strategies to recuperate trunk control (Table 4).^83,84) The limitation is the low level of evidence in the included studies. The reported studies used intervention methods and research designs for which bias was difficult to avoid. The primary objective of this review is to provide a comprehensive overview of existing knowledge and theories on the interventions for trunk control impairments, encompassing a wide range of approaches while maintaining methodological flexibility. In contrast, systematic reviews are designed to aggregate evidence according to rigid and strict protocols, which could lead to the exclusion of some relevant studies. Scoping reviews are typically used to map out research activity across a broad spectrum of fields without necessarily engaging deeply with theoretical contributions. This review, however, requires a broader discussion and theoretical exploration, making a traditional literature review more suitable for our purpose. Nonetheless, to establish a well-founded evidence base, a systematic review will be necessary in the future as more high-quality studies are reported. In addition, standardization of the intervention methodology is required according to difficulty level, strength, and frequency because of the large variability observed.

Table 4. Evidence level and recommendations for recuperation of trunk control

Treatment	Evidence level	Recommendation grade	Eligibility, usage, and effects	Considerations
Stroke
CSE	I-B	A	Used in online telecommunications at home follow-up Improves trunk stability, trunk muscle power, balance, and gait parameters	Need to adjust the difficulty level
WSE	II-B	B	Applicable for patients with poor spontaneity Improves verticality, balance, and reaching in standing positions	Need to adjust the seating condition, reaching direction, and difficulty level
Unstable surface training	I-B	A	Applicable for patients with poor spontaneity Increases trunk muscle reflex activity and improves coordination	Need to adjust seating condition, reaching direction, and difficulty level Risk of fall
TES	II-B	B	Changes motor cortical excitability, activates residual spinal motor neurons, and promotes neuroplasticity Improves muscle atrophy	Needs appropriate stimulation sites and parameters, and physical therapies to combine Risk of side effects
iTBS	II-B	B	Changes motor cortical excitability and promotes neuroplasticity	Needs appropriate stimulation parameters Risk of side effects
tDCS	II-B	B	Changes motor cortical excitability and promotes neuroplasticity	Needs appropriate stimulation sites and parameters, and physical therapies to combine
WBV	II-B	B	Activates motor units and proprioception	Limited evidence from few reports
Neurodevelopmental treatment-based trunk exercises	II-B	B	Improves balance and gait parameters	Limited evidence from few reports
Scapulohumeral rehabilitation	II-B	B	Improves power of scapular muscles	Indirect effects on trunk control
High-intensity training, three-dimensional training, dual-task practice	II-B	B	Improves trunk stability, trunk muscle power, balance, and gait parameters	Limited number of patients who can perform them
Arm and leg cycle ergometer	II-B	B	Improves trunk stability, trunk and upper and lower limb muscle power	No follow-up
Home-based boxing training	II-B	B	Improves trunk control, balance, and self-efficacy of balance functions	Not applicable for patients with paralysis of an upper limb
Lumbar joint mobilization	II-B	B	Improves spinal alignment, postural balance, and joint position sense	Limited number of therapists who can perform it
Cerebellar ataxia
TOT for balance function	II-B	B	Improves muscle strength, endurance, ROM, sensory awareness, and postural control Integrates sensorimotor functions of trunk	Need to grade difficulty levels by changing range and direction of movements No evidence in patients with degenerative cerebellar disease
CSE	II-B	B	Improves balance	Needs to adjust the difficulty level
WBV	II-B	B	Increases sensory inputs and spinal motoneuron excitability Improves proprioception for postural changes	Indirect effects on trunk control
Whole body exercise for balance	II-B	B	Improves balance and ataxic symptoms	Improves cardiopulmonary function
Parkinson’s disease
CSE	II-B	B	Improves posture alignment and balance	Difficult to adjust difficulty level in some cases
WBV	II-B	B	Improves balance and limb movements	Limited evidence from few reports
rTSMS	II-B	B	Improves trunk malalignment Enhances corticobulbar and corticospinal motor outputs	Limited evidence from few reports No follow-up
Perceptive rehabilitation	II-B	B	Improves trunk malalignment	Limited effects on balance
Postural rehabilitation with aquatic	II-B	B	Improves balance and self-efficacy for fall	Risk of drowning
Rehabilitation for trunk malalignment	II-B	B	Improves spinal deformity	Limited evidence from few reports

CSE: core-stability exercise, iTBS: intermittent theta-burst stimulation, NIBS: noninvasive brain stimulation, rTSMS: repetitive trans-spinal magnetic stimulation, tDCS: transcranial direct current stimulation, TES: transcutaneous electrical stimulation, TOT: task-oriented training, WBV: whole body vibration, WSE: weight-shifting exercise.

CONCLUSION

Rehabilitation treatments for trunk control impairments include CSE, WSE, unstable surface training, TES, NIBS, TOT, WBV, and perception tasks. TES or NIBS combined with physical therapy has been performed only in patients with stroke and not in those with cerebellar ataxia or PD. Further investigation is necessary to determine whether TES or NIBS has additional effects on these patients.

Overall, trunk control training showed some positive effects, improving balance in the standing position and gait function. However, their methodologies vary widely, and their effectiveness is inconsistent. A few studies have assessed trunk function, mainly in patients with cerebellar ataxia or PD. In the future, it will be necessary to standardize the intervention methodology regarding difficulty level, strength, frequency of training, and stimulation parameters of TES and NIBS with an integrative evaluation of trunk function, regardless of disease differences. This review highlights the importance of integrating evidence-based rehabilitation strategies into clinical practice to improve outcomes, ADL, and QOL for patients with neurological disorders affecting trunk control.

ACKNOWLEDGMENTS

This work was supported by the Japan Science and Technology Agency through a Grant-in-Aid for Core Research for Evolutional Science and Technology (JST-CREST)(JPMJCR23P3) (SK) and by the Japan Society for the Promotion of Science through Grants-in-Aid for Scientific Research (B) (21H03308, 23K21593), Scientific Research (A) (19H01091, 23H00459), Challenging Research (Exploratory) (23K18440), and Scientific Research on Innovative Areas (22H04788) (TM) and by AMED under Grant Number JP24zf0127010 (SK and TM).

CONFLICTS OF INTEREST

S. Koganemaru was a member of Department of Regenerative Systems Neuroscience, Human Brain Research Center, Graduate school of Medicine Kyoto University, which was endowed by the Kodama Foundation (April 2021 to March 2024). The other authors declare no conflict of interest.

REFERENCES

• 1.  Scuffham P, Chaplin S, Legood R: Incidence and costs of unintentional falls in older people in the United Kingdom. J Epidemiol Community Health 2003;57:740–744. PMID:12933783, DOI:10.1136/jech.57.9.740
• 2.  Lamb SE, Ferrucci L, Volapto S, Fried LP, Guralnik JM, Women’s Health and Aging Study: Risk factors for falling in home-dwelling older women with stroke: the Women’s Health and Aging Study. Stroke 2003;34:494–501. PMID:12574566, DOI:10.1161/01.STR.0000053444.00582.B7
• 3.  Karatas M, Çetin N, Bayramoglu M, Dilek A: Trunk muscle strength in relation to balance and functional disability in unihemispheric stroke patients. Am J Phys Med Rehabil 2004;83:81–87. PMID:14758293, DOI:10.1097/01.PHM.0000107486.99756.C7
• 4.  Franchignoni FP, Tesio L, Ricupero C, Martino MT: Trunk control test as an early predictor of stroke rehabilitation outcome. Stroke 1997;28:1382–1385. PMID:9227687, DOI:10.1161/01.STR.28.7.1382
• 5.  Hsieh CL, Sheu CF, Hsueh IP, Wang CH: Trunk control as an early predictor of comprehensive activities of daily living function in stroke patients. Stroke 2002;33:2626–2630. PMID:12411652, DOI:10.1161/01.STR.0000033930.05931.93
• 6.  Verheyden G, Vereeck L, Truijen S, Troch M, Herregodts I, Lafosse C, Nieuwboer A, De Weerdt W: Trunk performance after stroke and the relationship with balance, gait and functional ability. Clin Rehabil 2006;20:451–458. PMID:16774097, DOI:10.1191/0269215505cr955oa
• 7.  Pandolfo M: Neurologic outcomes in Friedreich ataxia: study of a single-site cohort. Neurol Genet 2020;6:e415. PMID:32337342, DOI:10.1212/NXG.0000000000000415
• 8.  Thijs L, Voets E, Denissen S, Mehrholz J, Elsner B, Lemmens R, Verheyden G: Trunk training following stroke. Stroke 2023;54:e427–e428. PMID:37639516, DOI:10.1161/STROKEAHA.123.043490
• 9.  Verheyden G, Nieuwboer A, Mertin J, Preger R, Kiekens C, De Weerdt W: The Trunk Impairment Scale: a new tool to measure motor impairment of the trunk after stroke. Clin Rehabil 2004;18:326–334. PMID:15137564, DOI:10.1191/0269215504cr733oa
• 10.  Chiou SY, Hurry M, Reed T, Quek JX, Strutton PH: Cortical contributions to anticipatory postural adjustments in the trunk. J Physiol 2018;596:1295–1306. PMID:29368403, DOI:10.1113/JP275312
• 11.  Dickstein R, Shefi S, Marcovitz E, Villa Y: Anticipatory postural adjustment in selected trunk muscles in poststroke hemiparetic patients. Arch Phys Med Rehabil 2004;85:261–267. PMID:14966711, DOI:10.1016/j.apmr.2003.05.011
• 12.  Deliagina TG, Beloozerova IN, Zelenin PV, Orlovsky GN: Spinal and supraspinal postural networks. Brain Res Brain Res Rev 2008;57:212–221. PMID:17822773, DOI:10.1016/j.brainresrev.2007.06.017
• 13.  Galea MP, Hammar I, Nilsson E, Jankowska E: Bilateral postsynaptic actions of pyramidal tract and reticulospinal neurons on feline erector spinae motoneurons. J Neurosci 2010;30:858–869. PMID:20089894, DOI:10.1523/JNEUROSCI.4859-09.2010
• 14.  Maiti B, Rawson KS, Tanenbaum AB, Koller JM, Snyder AZ, Campbell MC, Earhart GM, Perlmutter JS: Functional connectivity of vermis correlates with future gait impairments in Parkinson’s disease. Mov Disord 2021;36:2559–2568. PMID:34109682, DOI:10.1002/mds.28684
• 15.  Takakusaki K, Saitoh K, Harada H, Kashiwayanagi M: Role of basal ganglia–brainstem pathways in the control of motor behaviors. Neurosci Res 2004;50:137–151. PMID:15380321, DOI:10.1016/j.neures.2004.06.015
• 16.  Wijesinghe R, Protti DA, Camp AJ: Vestibular interactions in the thalamus. Front Neural Circuits 2015;9:79. PMID:26696836, DOI:10.3389/fncir.2015.00079
• 17.  Brugger F, Walch J, Hägele-Link S, Abela E, Galovic M, Kägi G: Decreased grey matter in the postural control network is associated with lateral flexion of the trunk in Parkinson’s disease. Neuroimage Clin 2020;28:102469. PMID:33395964, DOI:10.1016/j.nicl.2020.102469
• 18.  Lefaucheur JP, Aleman A, Baeken C, Benninger DH, Brunelin J, Di Lazzaro V, Filipović SR, Grefkes C, Hasan A, Hummel FC, Jääskeläinen SK, Langguth B, Leocani L, Londero A, Nardone R, Nguyen JP, Nyffeler T, Oliveira-Maia AJ, Oliviero A, Padberg F, Palm U, Paulus W, Poulet E, Quartarone A, Rachid F, Rektorová I, Rossi S, Sahlsten H, Schecklmann M, Szekely D, Ziemann U: Evidence-based guidelines on the therapeutic use of repetitive transcranial magnetic stimulation (rTMS): an update (2014–2018). Clin Neurophysiol 2020;131:474–528. PMID:31901449, DOI:10.1016/j.clinph.2019.11.002
• 19.  Souza DC, de Sales Santos M, da Silva Ribeiro NM, Maldonado IL: Inpatient trunk exercises after recent stroke: an update meta-analysis of randomized controlled trials. NeuroRehabilitation 2019;44:369–377.
• 20.  Gamble K, Chiu A, Peiris C: Core stability exercises in addition to usual care physiotherapy improve stability and balance after stroke: a systematic review and meta-analysis. Arch Phys Med Rehabil 2021;102:762–775. PMID:33239203, DOI:10.1016/j.apmr.2020.09.388
• 21.  Cabanas-Valdés R, Bagur-Calafat C, Girabent-Farrés M, Caballero-Gómez FM, Hernández-Valiño M, Urrútia Cuchí G: The effect of additional core stability exercises on improving dynamic sitting balance and trunk control for subacute stroke patients: a randomized controlled trial. Clin Rehabil 2016;30:1024–1033. PMID:26451007, DOI:10.1177/0269215515609414
• 22.  Cramer SC, Dodakian L, Le V, McKenzie A, See J, Augsburger R, Zhou RJ, Raefsky SM, Nguyen T, Vanderschelden B, Wong G, Bandak D, Nazarzai L, Dhand A, Scacchi W, Heckhausen J: A feasibility study of expanded home-based telerehabilitation after stroke. Front Neurol 2021;11:611453. PMID:33613417, DOI:10.3389/fneur.2020.611453
• 23.  Salgueiro C, Urrútia G, Cabanas-Valdés R: Influence of core-stability exercises guided by a telerehabilitation app on trunk performance, balance and gait performance in chronic stroke survivors: a preliminary randomized controlled trial. Int J Environ Res Public Health 2022;19:5689. PMID:35565084, DOI:10.3390/ijerph19095689
• 24.  Dean CM, Channon EF, Hall JM: Sitting training early after stroke improves sitting ability and quality and carries over to standing up but not to walking: a randomised trial. Aust J Physiother 2007;53:97–102. PMID:17535145, DOI:10.1016/S0004-9514(07)70042-9
• 25.  Masani K, Sin VW, Vette AH, Adam Thrasher T, Kawashima N, Morris A, Preuss R, Popovic MR: Postural reactions of the trunk muscles to multi-directional perturbations in sitting. Clin Biomech (Bristol, Avon) 2009;24:176–182. PMID:19150744, DOI:10.1016/j.clinbiomech.2008.12.001
• 26.  Sommer B, Haas M, Karrer S, Jörger M, Graf E, Huber M, Baumgartner D, Bansi J, Kool J, Bauer C: The effect on muscle activity of reaching beyond arm’s length on a mobile seat: a pilot study for trunk control training for people after stroke. Arch Rehabil Res Clin Transl 2023;5:100289. PMID:38163026, DOI:10.1016/j.arrct.2023.100289
• 27.  Fukata K, Amimoto K, Inoue M, Sekine D, Inoue M, Fujino Y, Makita S, Takahashi H: Effects of diagonally aligned sitting training with a tilted surface on sitting balance for low sitting performance in the early phase after stroke: a randomised controlled trial. Disabil Rehabil 2021;43:1973–1981. PMID:31714801, DOI:10.1080/09638288.2019.1688873
• 28.  Mückel S, Mehrholz J: Immediate effects of two attention strategies on trunk control on patients after stroke. A randomized controlled pilot trial. Clin Rehabil 2014;28:632–636. PMID:24452700, DOI:10.1177/0269215513513963
• 29.  Czaprowski D, Afeltowicz A, Gębicka A, Pawłowska P, Kędra A, Barrios C, Hadała M: Abdominal muscle EMG-activity during bridge exercises on stable and unstable surfaces. Phys Ther Sport 2014;15:162–168. PMID:24268641, DOI:10.1016/j.ptsp.2013.09.003
• 30.  Behm DG, Anderson K, Curnew RS: Muscle force and activation under stable and unstable conditions. J Strength Cond Res 2002;16:416–422. PMID:12173956
• 31.  Van Criekinge T, Saeys W, Vereeck L, De Hertogh W, Truijen S: Are unstable support surfaces superior to stable support surfaces during trunk rehabilitation after stroke? A systematic review. Disabil Rehabil 2018;40:1981–1988. PMID:28482696, DOI:10.1080/09638288.2017.1323030
• 32.  Lee PY, Huang JC, Tseng HY, Yang YC, Lin SI: Effects of trunk exercise on unstable surfaces in persons with stroke: a randomized controlled trial. Int J Environ Res Public Health 2020;17:9135. PMID:33297451, DOI:10.3390/ijerph17239135
• 33.  Knutson JS, Fu MJ, Sheffler LR, Chae J: Neuromuscular electrical stimulation for motor restoration in hemiplegia. Phys Med Rehabil Clin N Am 2015;26:729–745. PMID:26522909, DOI:10.1016/j.pmr.2015.06.002
• 34.  Mettler JA, Bennett SM, Doucet BM, Magee DM: Neuromuscular electrical stimulation and anabolic signaling in patients with stroke. J Stroke Cerebrovasc Dis 2017;26:2954–2963. PMID:28823492, DOI:10.1016/j.jstrokecerebrovasdis.2017.07.019
• 35.  Bilek F, Deniz G, Ercan Z, Cetisli Korkmaz N, Alkan G: The effect of additional neuromuscular electrical stimulation applied to erector spinae muscles on functional capacity, balance and mobility in post-stroke patients. NeuroRehabilitation 2020;47:181–189. PMID:32741788, DOI:10.3233/NRE-203114
• 36.  Tyson SF, Sadeghi-Demneh E, Nester CJ: The effects of transcutaneous electrical nerve stimulation on strength, proprioception, balance and mobility in people with stroke: a randomized controlled cross-over trial. Clin Rehabil 2013;27:785–791. PMID:23503739, DOI:10.1177/0269215513478227
• 37.  Yamaoka T, Takagi Y, Shimomura R, Murata Y, Shimotake K, Itoh A, Mima T, Koganemaru S: N-of-1 trial of electrical sensory stimulation therapy on the tibial innervated area during gait in a case of post-stroke sensory disturbance. Prog Rehabil Med 2023;8:20230018. PMID:37351114, DOI:10.2490/prm.20230018
• 38.  Jung KS, Jung JH, In TS, Cho HY: Effects of weight-shifting exercise combined with transcutaneous electrical nerve stimulation on muscle activity and trunk control in patients with stroke. Occup Ther Int 2016;23:436–443. PMID:27753145, DOI:10.1002/oti.1446
• 39.  Yada T, Amimoto K: Effects of task-related trunk training with sensory electrical stimulation on sitting balance in stroke survivors: a randomized controlled trial. Prog Rehabil Med 2023;8:20230037. PMID:37881244, DOI:10.2490/prm.20230037
• 40.  Celnik P: Understanding and modulating motor learning with cerebellar stimulation. Cerebellum 2015;14:171–174. PMID:25283180, DOI:10.1007/s12311-014-0607-y
• 41.  Koganemaru S, Fukuyama H, Mima T: Two is more than one: how to combine brain stimulation rehabilitative training for functional recovery? Front Syst Neurosci 2015;9:154. PMID:26617497, DOI:10.3389/fnsys.2015.00154
• 42.  Simis M, Di Lazzaro V, Kirton A, Pennisi G, Bella R, Kim YH, Takeuchi N, Khedr EM, Rogers LM, Harvey R, Koganemaru S, Turman B, Tarlacı S, Gagliardi RJ, Fregni F: Neurophysiological measurements of affected and unaffected motor cortex from a cross-sectional, multi-center individual stroke patient data analysis study. Neurophysiol Clin 2016;46:53–61. PMID:26970808, DOI:10.1016/j.neucli.2016.01.003
• 43.  O’Brien AT, Bertolucci F, Torrealba-Acosta G, Huerta R, Fregni F, Thibaut A: Non‐invasive brain stimulation for fine motor improvement after stroke: a meta‐analysis. Eur J Neurol 2018;25:1017–1026. PMID:29744999, DOI:10.1111/ene.13643
• 44.  Shibata S, Koganemaru S, Mima T: Non-invasive brain stimulation in post-stroke dysphagia rehabilitation: a narrative review of meta-analyses in 2022. Prog Rehabil Med 2023;8:20230015. PMID:37234861, DOI:10.2490/prm.20230015
• 45.  Klomjai W, Katz R, Lackmy-Vallée A: Basic principles of transcranial magnetic stimulation (TMS) and repetitive TMS (rTMS). Ann Phys Rehabil Med 2015;58:208–213. PMID:26319963, DOI:10.1016/j.rehab.2015.05.005
• 46.  Koganemaru S, Mima T, Thabit MN, Ikkaku T, Shimada K, Kanematsu M, Takahashi K, Fawi G, Takahashi R, Fukuyama H, Domen K: Recovery of upper-limb function due to enhanced use-dependent plasticity in chronic stroke patients. Brain 2010;133:3373–3384. PMID:20688810, DOI:10.1093/brain/awq193
• 47.  Koganemaru S, Sawamoto N, Aso T, Sagara A, Ikkaku T, Shimada K, Kanematsu M, Takahashi R, Domen K, Fukuyama H, Mima T: Task-specific brain reorganization in motor recovery induced by a hybrid-rehabilitation combining training with brain stimulation after stroke. Neurosci Res 2015;92:29–38. PMID:25450315, DOI:10.1016/j.neures.2014.10.004
• 48.  Xiang H, Sun J, Tang X, Zeng K, Wu X: The effect and optimal parameters of repetitive transcranial magnetic stimulation on motor recovery in stroke patients: a systematic review and meta-analysis of randomized controlled trials. Clin Rehabil 2019;33:847–864. PMID:30773896, DOI:10.1177/0269215519829897
• 49.  Liao LY, Xie YJ, Chen Y, Gao Q: Cerebellar theta-burst stimulation combined with physiotherapy in subacute and chronic stroke patients: a pilot randomized controlled trial. Neurorehabil Neural Repair 2021;35:23–32. PMID:33166213, DOI:10.1177/1545968320971735
• 50.  Sánchez-Kuhn A, Pérez-Fernández C, Cánovas R, Flores P, Sánchez-Santed F: Transcranial direct current stimulation as a motor neurorehabilitation tool: an empirical review. Biomed Eng Online 2017;16:76. PMID:28830433, DOI:10.1186/s12938-017-0361-8
• 51.  Lefaucheur JP, Antal A, Ayache SS, Benninger DH, Brunelin J, Cogiamanian F, Cotelli M, De Ridder D, Ferrucci R, Langguth B, Marangolo P, Mylius V, Nitsche MA, Padberg F, Palm U, Poulet E, Priori A, Rossi S, Schecklmann M, Vanneste S, Ziemann U, Garcia-Larrea L, Paulus W: Evidence-based guidelines on the therapeutic use of transcranial direct current stimulation (tDCS). Clin Neurophysiol 2017;128:56–92. PMID:27866120, DOI:10.1016/j.clinph.2016.10.087
• 52.  Bolognini N, Vallar G, Casati C, Latif LA, El-Nazer R, Williams J, Banco E, Macea DD, Tesio L, Chessa C, Fregni F: Neurophysiological and behavioral effects of tDCS combined with constraint-induced movement therapy in poststroke patients. Neurorehabil Neural Repair 2011;25:819–829. PMID:21803933, DOI:10.1177/1545968311411056
• 53.  Kaski D, Dominguez RO, Allum JH, Islam AF, Bronstein AM: Combining physical training with transcranial direct current stimulation to improve gait in Parkinson’s disease: a pilot randomized controlled study. Clin Rehabil 2014;28:1115–1124. PMID:24849794, DOI:10.1177/0269215514534277
• 54.  Chhatbar PY, Chen R, Deardorff R, Dellenbach B, Kautz SA, George MS, Feng W: Safety and tolerability of transcranial direct current stimulation to stroke patients—a phase I current escalation study. Brain Stimul 2017;10:553–559. PMID:28279641, DOI:10.1016/j.brs.2017.02.007
• 55.  Koganemaru S, Goto F, Arai M, Toshikuni K, Hosoya M, Wakabayashi T, Yamamoto N, Minami S, Ikeda S, Ikoma K, Mima T: Effects of vestibular rehabilitation combined with transcranial cerebellar direct current stimulation in patients with chronic dizziness: an exploratory study. Brain Stimul 2017;10:576–578. PMID:28274722, DOI:10.1016/j.brs.2017.02.005
• 56.  Nitsche MA, Paulus W: Excitability changes induced in the human motor cortex by weak transcranial direct current stimulation. J Physiol 2000;527:633–639. PMID:10990547, DOI:10.1111/j.1469-7793.2000.t01-1-00633.x
• 57.  Roche N, Geiger M, Bussel B: Mechanisms underlying transcranial direct current stimulation in rehabilitation. Ann Phys Rehabil Med 2015;58:214–219. PMID:26189791, DOI:10.1016/j.rehab.2015.04.009
• 58.  Monai H, Ohkura M, Tanaka M, Oe Y, Konno A, Hirai H, Mikoshiba K, Itohara S, Nakai J, Iwai Y, Hirase H: Calcium imaging reveals glial involvement in transcranial direct current stimulation-induced plasticity in mouse brain. Nat Commun 2016;7:11100. PMID:27000523, DOI:10.1038/ncomms11100
• 59.  Tedesco Triccas L, Burridge JH, Hughes AM, Pickering RM, Desikan M, Rothwell JC, Verheyden G: Multiple sessions of transcranial direct current stimulation and upper extremity rehabilitation in stroke: a review and meta-analysis. Clin Neurophysiol 2016;127:946–955. PMID:25998205, DOI:10.1016/j.clinph.2015.04.067
• 60.  Tedla JS, Rodrigues E, Ferreira AS, Vicente J, Reddy RS, Gular K, Sangadala DR, Kakaraparthi VN, Asiri F, Midde AK, Dixit S: Transcranial direct current stimulation combined with trunk-targeted, proprioceptive neuromuscular facilitation in subacute stroke: a randomized controlled trial. PeerJ 2022;10:e13329. PMID:35505681, DOI:10.7717/peerj.13329
• 61.  Martínez F, Rubio JA, Ramos DJ, Esteban P, Mendizábal S, Jiménez F: Effects of 6-week whole body vibration training on the reflex response of the ankle muscles: a randomized controlled trial. Int J Sports Phys Ther 2013;8:15–24. PMID:23439725
• 62.  Fontana TL, Richardson CA, Stanton WR: The effect of weightbearing exercise with low frequency, whole body vibration on lumbosacral proprioception: a pilot study on normal subjects. Aust J Physiother 2005;51:259–263. PMID:16321133, DOI:10.1016/S0004-9514(05)70007-6
• 63.  Kipp K, Johnson ST, Doeringer JR, Hoffman MA: Spinal reflex excitability and homosynaptic depression after a bout of whole‐body vibration. Muscle Nerve 2011;43:259–262. PMID:21254092, DOI:10.1002/mus.21844
• 64.  Lee JH, Kim SB, Lee KW, Lee SJ, Park H, Kim DW: The effect of a whole-body vibration therapy on the sitting balance of subacute stroke patients: a randomized controlled trial. Top Stroke Rehabil 2017;24:457–462. PMID:28335701, DOI:10.1080/10749357.2017.1305655
• 65.  Ashizawa T, Xia G: Ataxia. Continuum (Minneap Minn) 2016;22:1208–1226. PMID:27495205, DOI:10.1212/CON.0000000000000362
• 66.  Rensink M, Schuurmans M, Lindeman E, Hafsteinsdóttir T: Task‐oriented training in rehabilitation after stroke: systematic review. J Adv Nurs 2009;65:737–754. PMID:19228241, DOI:10.1111/j.1365-2648.2008.04925.x
• 67.  Jang SH, Kim YH, Cho SH, Lee JH, Park JW, Kwon YH: Cortical reorganization induced by task-oriented training in chronic hemiplegic stroke patients. Neuroreport 2003;14:137–141. PMID:12544845, DOI:10.1097/00001756-200301200-00025
• 68.  Ali AS, Darwish MH, Shalaby NM, Abbas RL, Soubhy HZ: Efficacy of core stability versus task oriented trainings on balance in ataxic persons with multiple sclerosis. A single blinded randomized controlled trial. Mult Scler Relat Disord 2021;50:102866. PMID:33652233, DOI:10.1016/j.msard.2021.102866
• 69.  Doğan M, Ayvat E, Kılınç M: Telerehabilitation versus virtual reality supported task-oriented circuit therapy on upper limbs and trunk functions in patients with multiple sclerosis: a randomized controlled study. Mult Scler Relat Disord 2023;71:104558. PMID:36812718, DOI:10.1016/j.msard.2023.104558
• 70.  Yigit S, Usgu S, Albayrak HM, Yücel PP, Yakut Y: Effectiveness of functional trunk training on trunk control and upper limb functions in patients with autosomal recessive hereditary ataxia. NeuroRehabilitation 2022;51:41–50. PMID:35311719, DOI:10.3233/NRE-210320
• 71.  Liu H, Yin H, Yi Y, Liu C, Li C: Effects of different rehabilitation training on balance function in stroke patients: a systematic review and network meta-analysis. Arch Med Sci 2023;19:1671–1683. PMID:38058731, DOI:10.5114/aoms/167385
• 72.  Ayvat E, Kılınç M, Ayvat F, Onursal Kılınç Ö, Aksu Yıldırım S: The effect of whole body vibration on postural control of ataxic patients: a randomized controlled cross-over study. Cerebellum 2021;20:533–541. PMID:33475935, DOI:10.1007/s12311-021-01233-y
• 73.  Johansson H, Sjölander P, Sojka P: Activity in receptor afferents from the anterior cruciate ligament evokes reflex effects on fusimotor neurones. Neurosci Res 1990;8:54–59. PMID:2163050, DOI:10.1016/0168-0102(90)90057-L
• 74.  Litvan I, Bhatia KP, Burn DJ, Goetz CG, Lang AE, McKeith I, Quinn N, Sethi KD, Shults C, Wenning GK, Movement Disorders Society Scientific Issues Committee: Movement Disorders Society Scientific Issues Committee report: SIC Task Force appraisal of clinical diagnostic criteria for Parkinsonian disorders. Mov Disord 2003;18:467–486. PMID:12722160, DOI:10.1002/mds.10459
• 75.  Horak FB, Wrisley DM, Frank J: The Balance Evaluation Systems Test (BESTest) to differentiate balance deficits. Phys Ther 2009;89:484–498. PMID:19329772, DOI:10.2522/ptj.20080071
• 76.  Seki M, Takahashi K, Koto A, Mihara B, Morita Y, Isozumi K, Ohta K, Muramatsu K, Gotoh J, Yamaguchi K, Tomita Y, Sato H, Nihei Y, Iwasawa S, Suzuki N, Keio Parkinson’s Disease Database: Camptocormia in Japanese patients with Parkinson’s disease: a multicenter study. Mov Disord 2011;26:2567–2571. PMID:21953897, DOI:10.1002/mds.23955
• 77.  Cabrera-Martos I, Jiménez-Martín AT, López-López L, Rodríguez-Torres J, Ortiz-Rubio A, Valenza MC: Effects of a core stabilization training program on balance ability in persons with Parkinson’s disease: a randomized controlled trial. Clin Rehabil 2020;34:764–772. PMID:32349543, DOI:10.1177/0269215520918631
• 78.  Gandolfi M, Tinazzi M, Magrinelli F, Busselli G, Dimitrova E, Polo N, Manganotti P, Fasano A, Smania N, Geroin C: Four-week trunk-specific exercise program decreases forward trunk flexion in Parkinson’s disease: a single-blinded, randomized controlled trial. Parkinsonism Relat Disord 2019;64:268–274. PMID:31097299, DOI:10.1016/j.parkreldis.2019.05.006
• 79.  Morrone M, Miccinilli S, Bravi M, Paolucci T, Melgari JM, Salomone G, Picelli A, Spadini E, Ranavolo A, Saraceni VM, DI Lazzaro V, Sterzi S: Perceptive rehabilitation and trunk posture alignment in patients with Parkinson disease: a single blind randomized controlled trial. Eur J Phys Rehabil Med 2016;52:799–809. PMID:27171537
• 80.  Volpe D, Giantin MG, Manuela P, Filippetto C, Pelosin E, Abbruzzese G, Antonini A: Water-based vs. non-water-based physiotherapy for rehabilitation of postural deformities in Parkinson’s disease: a randomized controlled pilot study. Clin Rehabil 2017;31:1107–1115. PMID:27512099, DOI:10.1177/0269215516664122
• 81.  Arii Y, Sawada Y, Kawamura K, Miyake S, Taichi Y, Izumi Y, Kuroda Y, Inui T, Kaji R, Mitsui T: Immediate effect of spinal magnetic stimulation on camptocormia in Parkinson’s disease. J Neurol Neurosurg Psychiatry 2014;85:1221–1226. PMID:24780955, DOI:10.1136/jnnp-2014-307651
• 82.  Karthikbabu S, Ganesan S, Ellajosyula R, Solomon JM, Kedambadi RC, Mahabala C: Core stability exercises yield multiple benefits for patients with chronic stroke: a randomized controlled trial. Am J Phys Med Rehabil 2022;101:314–323. PMID:34001840, DOI:10.1097/PHM.0000000000001794
• 83.  Shekelle PG, Woolf SH, Eccles M, Grimshaw J: Developing clinical guidelines. West J Med 1999;170:348–351. PMID:18751155
• 84.OCEBM Levels of Evidence Working Group: Oxford Centre for Evidence-Based Medicine: Levels of Evidence (March 2009). https://www.cebm.ox.ac.uk/resources/levels-of-evidence/oxford-centre-for-evidence-based-medicine-levels-of-evidence-march-2009.
• 85.  Haruyama K, Kawakami M, Otsuka T: Effect of core stability training on trunk function, standing balance, and mobility in stroke patients. Neurorehabil Neural Repair 2017;31:240–249. PMID:27821673, DOI:10.1177/1545968316675431
• 86.  Park HK, Lee HJ, Lee SJ, Lee WH: Land-based and aquatic trunk exercise program improve trunk control, balance and activities of daily living ability in stroke: a randomized clinical trial. Eur J Phys Rehabil Med 2019;55:687–694. PMID:30370752
• 87.  Van Criekinge T, Hallemans A, Herssens N, Lafosse C, Claes D, De Hertogh W, Truijen S, Saeys W: SWEAT2 Study: effectiveness of trunk training on gait and trunk kinematics after stroke: a randomized controlled trial. Phys Ther 2020;100:1568–1581. PMID:32542356, DOI:10.1093/ptj/pzaa110
• 88.  Cho YH, Cho K, Park SJ: Effects of trunk rehabilitation with kinesio and placebo taping on static and dynamic sitting postural control in individuals with chronic stroke: a randomized controlled trial. Top Stroke Rehabil 2020;27:610–619. PMID:32252619, DOI:10.1080/10749357.2020.1747672
• 89.  Kim DH, In TS, Jung KS: Effects of robot-assisted trunk control training on trunk control ability and balance in patients with stroke: a randomized controlled trial. Technol Health Care 2022;30:413–422. PMID:34657856, DOI:10.3233/THC-202720
• 90.  Jung KS, Jung JH, In TS, Cho HY: Effects of pelvic stabilization training with lateral and posterior tilt taping on pelvic inclination, muscle strength, and gait function in patients with stroke: a randomized controlled study. BioMed Res Int 2022;2022:1–9. PMID:37333857, DOI:10.1155/2022/9224668
• 91.  Fujino Y, Amimoto K, Fukata K, Ishihara S, Makita S, Takahashi H: Does training sitting balance on a platform tilted 10° to the weak side improve trunk control in the acute phase after stroke? A randomized, controlled trial. Top Stroke Rehabil 2016;23:43–49. PMID:26245847, DOI:10.1179/1945511915Y.0000000010
• 92.  Sheehy L, Taillon-Hobson A, Sveistrup H, Bilodeau M, Yang C, Finestone H: Sitting balance exercise performed using virtual reality training on a stroke rehabilitation inpatient service: a randomized controlled study. PM R 2020;12:754–765. PMID:31970898, DOI:10.1002/pmrj.12331
• 93.  Jung KM, Joo MC, Jung YJ, Jang WN: The effects of the three-dimensional active trunk training exercise on trunk control ability, trunk muscle strength, and balance ability in sub-acute stroke patients: a randomized controlled pilot study. Technol Health Care 2021;29:213–222. PMID:32568128, DOI:10.3233/THC-181179
• 94.  Jung K, Kim Y, Chung Y, Hwang S: Weight-shift training improves trunk control, proprioception, and balance in patients with chronic hemiparetic stroke. Tohoku J Exp Med 2014;232:195–199. PMID:24646921, DOI:10.1620/tjem.232.195
• 95.  Karthikbabu S, Chakrapani M, Ganesan S, Ellajosyula R, Solomon JM: Efficacy of trunk regimes on balance, mobility, physical function, and community reintegration in chronic stroke: a parallel-group randomized trial. J Stroke Cerebrovasc Dis 2018;27:1003–1011. PMID:29361348, DOI:10.1016/j.jstrokecerebrovasdis.2017.11.003
• 96.  Shin DC: Smartphone-based visual feedback trunk control training for gait ability in stroke patients: a single-blind randomized controlled trial. Technol Health Care 2020;28:45–55. PMID:31104034, DOI:10.3233/THC-191647
• 97.  Thijs L, Voets E, Wiskerke E, Nauwelaerts T, Arys Y, Haspeslagh H, Kool J, Bischof P, Bauer C, Lemmens R, Baumgartner D, Verheyden G: Technology-supported sitting balance therapy versus usual care in the chronic stage after stroke: a pilot randomized controlled trial. J Neuroeng Rehabil 2021;18:120. PMID:34321042, DOI:10.1186/s12984-021-00910-7
• 98.  Aphiphaksakul P, Siriphorn A: Home-based exercise using balance disc and smartphone inclinometer application improves balance and activity of daily living in individuals with stroke: a randomized controlled trial. PLoS One 2022;17:e0277870. PMID:36409753, DOI:10.1371/journal.pone.0277870
• 99.  Yeo SS, Koo DK, Ko SY, Park SY: Effect of balance training in sitting position using visual feedback on balance and gait ability in chronic stroke patients. J Clin Med 2023;12:4383. PMID:37445418, DOI:10.3390/jcm12134383
• 100.  Chan BK, Ng SS, Ng GY: A home-based program of transcutaneous electrical nerve stimulation and task-related trunk training improves trunk control in patients with stroke: a randomized controlled clinical trial. Neurorehabil Neural Repair 2015;29:70–79. PMID:24795163, DOI:10.1177/1545968314533612
• 101.  Saeys W, Vereeck L, Lafosse C, Truijen S, Wuyts FL, Van De Heyning P: Transcranial direct current stimulation in the recovery of postural control after stroke: a pilot study. Disabil Rehabil 2015;37:1857–1863. PMID:25401406, DOI:10.3109/09638288.2014.982834
• 102.  Choi SJ, Shin WS, Oh BK, Shim JK, Bang DH: Effect of training with whole body vibration on the sitting balance of stroke patients. J Phys Ther Sci 2014;26:1411–1414. PMID:25276025, DOI:10.1589/jpts.26.1411
• 103.  Kılınç M, Avcu F, Onursal O, Ayvat E, Savcun Demirci C, Aksu Yildirim S: The effects of Bobath-based trunk exercises on trunk control, functional capacity, balance, and gait: a pilot randomized controlled trial. Top Stroke Rehabil 2016;23:50–58. PMID:26260878, DOI:10.1179/1945511915Y.0000000011
• 104.  Dell’Uomo D, Morone G, Centrella A, Paolucci S, Caltagirone C, Grasso MG, Traballesi M, Iosa M: Effects of scapulohumeral rehabilitation protocol on trunk control recovery in patients with subacute stroke: a pilot randomized controlled trial. NeuroRehabilitation 2017;40:337–343. PMID:28222555, DOI:10.3233/NRE-161421
• 105.  Ahmed U, Karimi H, Amir S, Ahmed A: Effects of intensive multiplanar trunk training coupled with dual-task exercises on balance, mobility, and fall risk in patients with stroke: a randomized controlled trial. J Int Med Res 2021;49:03000605211059413. PMID:34812070, DOI:10.1177/03000605211059413
• 106.  Bharti A, Balaji GK, Agrahara S: Effect of early bedside arm and leg cycle ergometry on sitting and standing ability in hospitalized acute stroke patients: a randomized controlled trial. Neurol India 2022;70:2065–2071. PMID:36352610, DOI:10.4103/0028-3886.359229
• 107.  Kerdsawatmongkon J, Nualnetr N, Isariyapan O, Kitreerawutiwong N, Srisoparb W: Effects of home-based boxing training on trunk performance, balance, and enjoyment of patients with chronic stroke. Ann Rehabil Med 2023;47:36–44. PMID:36635885, DOI:10.5535/arm.22127
• 108.  Choi W, Lee J, Lee S: Effects of lumbar joint mobilization on trunk function, postural balance, and gait in patients with chronic stroke: a randomized pilot study. J Back Musculoskeletal Rehabil 2023;36:79–86. PMID:35938238, DOI:10.3233/BMR-200046
• 109.  Elshafey MA, Abdrabo MS, Elnaggar RK: Effects of a core stability exercise program on balance and coordination in children with cerebellar ataxic cerebral palsy. J Musculoskelet Neuronal Interact 2022;22:172–178. PMID:35642697
• 110.  Barbuto S, Martelli D, Isirame O, Lee N, Bishop L, Kuo SH, Agrawal S, Lee S, O’Dell M, Stein J: Phase I single‐blinded randomized controlled trial comparing balance and aerobic training in degenerative cerebellar disease. PM R 2021;13:364–371. PMID:32383352, DOI:10.1002/pmrj.12401
• 111.  Hubble RP, Silburn PA, Naughton GA, Cole MH: Trunk exercises improve balance in Parkinson disease: a phase II randomized controlled trial. J Neurol Phys Ther 2019;43:96–105. PMID:30883497, DOI:10.1097/NPT.0000000000000258
• 112.  Vasconcellos LS, Silva RS, Pachêco TB, Nagem DA, Sousa CO, Ribeiro TS: Telerehabilitation-based trunk exercise training for motor symptoms of individuals with Parkinson’s disease: a randomized controlled clinical trial. J Telemed Telecare 2023;29:698–706. PMID:34142896, DOI:10.1177/1357633X211021740
• 113.  Li K, Cho Y, Chen R: The effect of whole-body vibration on proprioception and motor function for individuals with moderate Parkinson disease: a single-blind randomized controlled trial. Occup Ther Int 2021;2021:1–9. PMID:34992511, DOI:10.1155/2021/9441366
• 114.  Jean-Pascal Lefaucheur, André Aleman, Chris Baeken, David H. Benninger, Jérôme Brunelin, Vincenzo Di Lazzaro, Saša R. Filipović, Christian Grefkes, Alkomiet Hasan, Friedhelm C. Hummel, Satu K. Jääskeläinen, Berthold Langguth, Letizia Leocani, Alain Londero, Raffaele Nardone, Jean-Paul Nguyen, Thomas Nyffeler, Albino J. Oliveira-Maia, Antonio Oliviero, Frank Padberg, Ulrich Palm, Walter Paulus, Emmanuel Poulet, Angelo Quartarone, Fady Rachid, Irena Rektorová, Simone Rossi, Hanna Sahlsten, Martin Schecklmann, David Szekely, Ulf Ziemann: Corrigendum to “Evidence-based guidelines on the therapeutic use of repetitive transcranial magnetic stimulation (rTMS): An update (2014–2018)” [Clin. Neurophysiol. 131 (2020) 474–528]. Clin Neurophysiol 2020;131:1168–1169. PMID:32122766, DOI:10.1016/j.clinph.2020.02.003