The purpose of this study was to determine the effects of differences in subjective perceptions of muscle contraction intensity of movements presented during exercise observation on the excitability of spinal motor nerve function. The subjects were 22 healthy adults, and F-waves were derived from a muscle group on the right thenar eminence. The measurement flow consisted of measuring the F-wave at rest for 1 minute, followed by 4 minutes of rest, and then measuring the F-wave during movement observation for 1 minute. The observation task consisted of an adduction/abduction movement of the thumb (unloaded video) and loading the thumb with two types of therabands (low and high loading video). Based on the subject's perception, the subjects were classified into subjective high load, subjective low load, and subjective no load, and the amplitude F/M ratio relative values between each condition were compared. The amplitude F/M ratio relative values increased in the subjective high-load condition compared to the subjective no-load and low-load conditions (p<0.05). The results suggest that the excitability of spinal motor nerve function increases when the subject is made aware during exercise observation that the exercise requires strong muscle contraction.

Objective: This study was designed to investigate the effects of continuous pressure stimulus (CPS) of the thoracolumbar region on bowel sound (BS) and autonomic nervous system activity.
Methods: In this study, 12 healthy women (mean age, 22.5 ± 1.3 years, height 1.56 ± 0.05 m, weight 51.8 ± 4.2 kg, BMI 21.4 ± 1.7 kg/m²) were enrolled as the subjects. The survey items included voiding and quality of life questionnaires, and blood pressure (BP) levels were measured and the subjects underwent electrocardiogram. CPS to the thoracolumbar spine was performed at 30 mmHg for 15 min, and pre- and post-CPS comparisons were performed using Fisher's least significant difference for BS, heart rate (HR), and HR variability analysis as two-way repeated measures analysis of variance and multiple comparison methods and a paired t-test for BP.
Results: As for the simple main effects before and after CPS, the intervention group showed significant increases in BS, low frequency (LF), and LF/high frequency ratio 5 min after CPS, and the control group showed significant decreases in HR 5 and 10 min after CPS. However, no interaction was observed between the two groups.
Conclusion: CPS to the lateral skin of the thoracolumbar spine is suggested to induce intestinal peristalsis in the physiological range.

Purpose: Activation of fibroblasts constituting the anterior cruciate ligament (ACL) is necessary to realize conservative treatment after ACL injury. Therefore, we focused on the adjacent adipose tissue, the sub patellar adipose tendon, and conducted culture experiments to confirm the activation of ACL-derived fibroblasts through cell-to-cell interaction.

Methods: Fibroblasts were dispersed from the ACL of male Wistar rats, and fibroblasts from third passage were used in the experiment. Two groups were used: a Mono-culture group and a Co-culture group (co-culture with infrapatellar fat pad collected from living animals). In addition to wound healing studies, real-time qPCR analysis was performed to examine gene expression levels.

Results: In the wound healing study, significant cell infiltration into the wound was observed in the Co-culture group compared to the Mono-culture group. However, there was no difference in the number of infiltrated cells, and no significant difference in the gene expression of TGFβ1, which is involved in fibroblast proliferation and migration.

Conclusion: It was suggested that co-culture with infrapatellar fat pad enhances the migratory ability of ACL-derived fibroblasts, but the mechanism needs to be further verified.

When sensory perception is impaired, motor coordination becomes difficult. Thus, ways to cue with target objects during therapeutic exercise must be devised. This study investigated the effect of thumb motion adjustment on short-latency somatosensory evoked potentials (SEP). Twenty healthy adults participated in this study. Electrical stimulation to evoke the SEP was administrated the right median nerve at the wrist. All the subjects performed tasks involving repetitive palmar abduction movements, in which the right thumb was moved from 0° to 20° at a frequency of 1 Hz. Task 1 had no target (non-target task), while Task 2 had a palpable convex target at 20° (target task). Compared to the other amplitudes, those for the N9 and N13 amplitudes were the same in both tasks. The N20 amplitude was significantly lower in non-target task and target task than in the rest and significantly lower in non-target task than in target task. The absolute error was significantly lower in target task than in non-target task. Somatosensory input was suppressed and the N20 amplitude derived from the primary somatosensory cortex was decreased during voluntary movements. However, target task showed a weakened suppression effect compared to non-target task because the subjects made precise motor adjustments based on tactile stimulation. These findings suggested that motor control based on tactile stimulation might decrease the amount of gating in the thalamus and primary somatosensory cortex.

The fall rate among pregnant women is nearly 20%, highlighting a significant concern. This study aimed to identify factors associated with falls in pregnant women and investigate walking and crossing-over movement characteristics during the late stages of pregnancy. Twenty healthy young women were assessed for the accuracy of their motor imagery during walking, while nine participants were evaluated for toe clearance during obstacle crossing both with and without simulated pregnant women's experience jackets. The participants were also queried about their fear of falling using the ABC scale while wearing the simulated pregnant women's experience jacket. The results revealed a significant underestimation in motor imagery accuracy for a maximum walk of 10 meters when participants wore the simulated pregnant women's experience jacket. The mean value of the ABC scale was 54.2%, indicating a high fear of falls. During the obstacle crossing, the toe clearance of the trailing foot while carrying a load was greater compared to crossing without a load. Furthermore, the toe clearance of the trailing foot when crossing lower obstacles with the simulated pregnant women's experience jacket was lower than that without it. The high incidence of falls among pregnant women was thought to be due to their tendency to lose balance when crossing obstacles while carrying luggage because they raise their lower limbs significantly to ensure clearance, which in turn predisposed them to tripping over low obstacles due to insufficient clearance.

<Introduction> A Freeze Index (FI), calculated from acceleration, is reported objective assessment of freezing of gait. In this study, we investigated the attachment site of the accelerometer and the window width of FI from a feature selection perspective to explore effective measurement methods for FI. <Methods> We included 7 patients with Parkinson’s disease. Accelerometers were attached to the third lumbar spinous process and the distal part of both shins. FI was calculated by STFT analysis. FI was calculated using a single sensor (lumbar, right shin, left shin) and multiple sensors (both shins, lumbar and both shins) at 6 different window widths (1-6 second). We ranked each FI value based on mutual information and Euclidean distance by feature selection. <Results> The top selected features based on both indicators were the FI calculated using a single sensor (right shin, left shin, and lumbar) with a window width of 6 second and the FI calculated using the lumbar and both shins (max) with a window width of 1 second. <Conclusion> This study suggested that a 6-second window width FI by a single sensor is beneficial.

Static stretching is widely used to improve joint range of motion, decrease stiffness, and prevent injury. Previous studies have shown that joint range of motion is improved after static stretching. However, the effects of static stretching on stiffness and muscle/tendon injuries are not clear. Therefore, we conducted a systematic review and meta-analysis to investigate the effects of static stretching on muscle-tendon unit stiffness, muscle stiffness, muscle injuries, and tendon injuries. The results of our study revealed that long-term static stretching decreased muscle stiffness but did not change muscle-tendon unit stiffness. Static stretching also decreased the number of events of muscle injuries but did not change the number of tendon injuries. These results suggest that static stretching has a significant effect on muscle, and as a result, is useful in decreasing muscle stiffness and preventing muscle injuries.

The perception of somatosensory stimuli requires highly complex processing within the brain. It is well-established that the primary somatosensory cortex, located in the postcentral gyrus, is closely involved in perception. Recent advancements in brain imaging technology and brain analysis techniques have illuminated the cooperative involvement of multiple brain regions in somatosensory processing, beyond the primary somatosensory cortex alone. Our research group has focused on one aspect of somatosensory processing, namely two-point discrimination, revealing the involvement of various brain regions in this process from both functional and structural perspectives. In this review, we discuss the roles of specific cortical regions involved in two-point discrimination based on these preceding studies. We also address our latest findings and challenges in non-invasive brain stimulation strategies aimed at enhancing somatosensory function. Furthermore, we introduce additional strategies derived from our brain imaging research and explore their potential application in the rehabilitation of somatosensory impairments following stroke.

Resistance training prescriptions in time-limited clinical settings must produce increases in muscle strength and muscle hypertrophy efficiently. Therefore, we investigated the effects of different joint angles and muscle contraction types on muscle strength and muscle hypertrophy in resistance training. Our results showed that resistance training in the joint angle in muscle elongating position, compared to the joint angle with muscle shortening position, significantly increased maximal muscle strength and thickness of elbow flexors. Furthermore, it was possible to show that resistance training using eccentric contractions may be more effective in increasing muscle strength and muscle hypertrophy than training using other muscle contraction types. These results suggested that incorporating joint angle with muscle-stretching and eccentric contractions in resistance training prescriptions may increase muscle strength and hypertrophy effects.

Recently, a non-invasive algorithm has been developed for the analysis of motor unit firing behavior, which employs a high-density surface electromyography (HD-sEMG). A validated convolutive blind source separation method can separately the HD-sEMG recordings into individual motor unit discharge timings. In general, intramuscular EMG has been used for detailed evaluation of motor unit firing behavior, but it has several disadvantages, such as painful method, sampling bias, and limitation of motor tasks. HD-sEMG with more than 60 surface electrodes allow this technique to increase the number of detectable motor units compared to intramuscular EMG and to investigate detailed motor unit firing characteristics, such as the relationship of firing rates between motor units with different recruitment thresholds. Therefore, HD-sEMG method can be used to noninvasively identify the activity of the motor units and can be used to uncover unknown mechanisms of the central nervous system in physiology field. It is the purpose of this review to provide an overview of the characteristics of the firing behavior of the motor unit, both in healthy individuals and in patients with neurodegenerative diseases in this review.

Sensory augmented biofeedback (BF) training has been used as an intervention to improve postural control. Various forms of sensory information including visual, auditory, and somatosensory have been used to provide real-time augmented BF in the field of rehabilitation. However, most previous studies of postural control using sensory BF have used visual BF. In addition, no study that compared the learning effects of postural control using different sensory modalities. Therefore, the effective interventions using sensory BF for motor learning of postural control are still unclear. Then, we have investigated the learning effects of visual and auditory BF training for postural control using a voluntary postural sway task. A series of experiments showed that visual BF training could interfere with motor learning of postural control and that some restrictions should apply to visual BF in order to obtain learning effects of postural control. Lastly, the results of these studies revealed that auditory BF training is more effective in motor learning of postural control compared to visual BF training regardless of any restrictions applied to sensory BF. These findings would contribute to the development of efficient sensory feedback approaches for postural control impairments.