Endurance exercises such as cycling and running are useful for improving the arterial function and preventing cardiovascular disease (CVD). However, subjects suffering from spinal cord injury (SCI) or lower limb osteoarthritis (OA) cannot perform these kinds of lower limb exercises. Recently, electrical muscle stimulation (EMS) has been shown to be able to increase the muscle strength and blood flow and improve the peripheral circulation. Arm-cranking exercises with EMS may therefore be able to reduce the risk of CVD for patients with SCI and lower OA. However, this point has not been fully clarified. The purpose of this study was to assess the effect of submaximal arm-cranking exercise with EMS on arterial stiffness. Ten healthy young subjects performed submaximal arm-cranking exercise alone (A) and submaximal arm-cranking exercise with EMS (A+E). In the A+E trial, the submaximal arm-cranking exercise was performed at 30%VO2 max for 20 min while EMS was applied to their thigh and calf muscles during the exercise. The brachial-ankle pulse wave velocity (ba-PWV), systolic and diastolic blood pressure (SBP/DBP) and heart rate (HR) were measured before and after each exercise. Immediately after the exercise session, the HR of the subjects in the A+E trial was significantly elevated in comparison to those in the A trial. The SBP and DBP did not differ between the two trials to a statistically significant extent. In the A+E trial, the ba-PWV was significantly reduced immediately after exercise in comparison to the A trial (1082.6 ± 105.9 cm·sec-1 vs. 1191.7 ± 86.7 cm·sec-1, p < 0.05). These findings suggest that arm-cranking exercise with EMS reduces arterial stiffness and might be useful for reducing the risk of CVD.
To investigate the effects of training focused on the movement velocity of the lower limbs (movement velocity training) on short sprint performance in young female non-athletes. Twenty-nine healthy young females (mean age: 20.1 ± 0.9 years) participated in this study. The subjects were randomized into a movement velocity training group (MV group, n=15) and a resistance training group (R group, n=14). MV group performed six lower limb exercises at high velocity (as fast as possible) with no load. R group performed five lower limb strength exercises using a resistance band. Both training programs were applied for 20 minutes per session, 5 days a week for 6 weeks. The following outcomes were measured at baseline and after 6 weeks of training: 30 m sprint time, 20- 26m running velocity, step length, step frequency, and muscle strength and movement velocity of knee extension. Significant group × time interactions were observed for the 30-m sprint time with the MV group exhibiting a significant improvement on simple main effect analysis. For the other parameters (step length, step frequency, and muscle strength and movement velocity of knee extension), group × time interactions were not observed and a significant main effect was observed. These findings suggest that training focused on the movement velocity of the lower limbs can be effective for improving sprint performance.
High-intensity interval exercise leads to greater improvements in the vascular endothelial function than continuous exercise at moderate intensity. However, few studies have been performed on the effects of repetition exercise consisting of high-intensity exercise followed by complete rest on the arterial function. Therefore, the purpose of this study was to investigate the effects of repetition exercise on the vascular endothelial function determined by flow-mediated vasodilation (FMD). Eleven healthy male subjects completed two exercise sessions on a cycle ergometer in a counterbalanced order. The exercise sessions were 20 min cycling at 50% maximal work rate (Wmax) (continuous exercise, CE) and 20 × 20-sec intervals at 100%Wmax interspersed with 40-sec intervals at complete rest (repetition exercise, RE). Before and after each protocol, the brachial systolic and diastolic blood pressure were measured in the supine position. Relative FMD was assessed at rest and 30 and 60 min after each exercise regimen, and then the normalized FMD (nFMD) was calculated from the peak shear rate. The FMD significantly increased 30 min after RE (8.2 ± 1.5% to 11.5 ± 3.1%, p<0.01) and non-significantly increased 30 min after CE (7.5 ± 1.6% to 8.1 ± 2.1%, n.s.) before returning to baseline at 60 min after both exercise regimens. The FMD value at 30 min after RE was significantly greater than that at 30 min after CE (p<0.01). The nFMD (a.u.) significantly increased 30 min after RE (1.38 ± 0.64 to 2.00 ± 0.94, p<0.05) and non-significantly increased 30 min after CE (1.20 ± 0.54 to 1.49 ± 0.57, n.s.) before returning to baseline at 60 min after both exercise regimens. These results suggest that repetition exercise may lead to an acute improvement in the vascular endothelial function.
The primary aim of this study was to examine moderate-to-vigorous physical activity (MVPA) levels in preschool children during indoor and outdoor free playing time and during preschool physical education (PE) classes. The secondary aim was to determine which types of PE lessons are the best for increasing the percentage of MVPA. Physical activity during free playing time and in lessons was objectively evaluated with a triaxial accelerometer in preschool boys and girls (n = 281). Minutes of physical activity were categorized into physical activity ratios (PAR). MVPA was defined as PAR ≥3.0. Time tables and PE lesson types were recorded using logs kept by class teachers. The percentage of MVPA in outdoor free playing time (38.9±16.3%) was significantly higher than that of indoor free playing time (12.6±10.1%, p<0.001). On the other hand, there was no significant difference between the percentage in MVPA in outdoor free playing time and the percentage in PE lessons (n=94: 38.0±19.4%vs. 34.9±15.8%, ns). After adjustment for gender, age, body height and weight and preschool, there were not significantly different the percentage of MVPA among contents of PE lessons. In conclusion, children engaged in almost 30~40% MVPA during outdoor free playing time or PE. The children also engaged MVPA during indoor free playing time.
In this study, we investigated the relationship of an osteoarthritis of the knee (OA) and a knee pain of single-leg on the bilateral difference of ground reaction force in stepping. The subjects were 29 middle-aged women (mean age 63.7±6.7 years). We categorized them into groups based on the following conditions: osteoarthritis of the knee (OA groups; n = 9), knee pain (KP groups; n = 7), and no pain (NP groups; n = 13). We measured the ground reaction force in a vertical direction when stepping on a platform. The evaluation variables were as follows: peak of ground reaction force at the early stance phase (F1), middle phase (F2), and late phase (F3). We calculated the bilateral difference of ground reaction force of the left and right leg and the affected side and the unaffected side ratio. The result of two way ANOVA, there was a significant difference between the leg in F1 and F3 and the group at F2. The result of comparison between the OA groups and the KP groups, there was no significant difference in the unaffected side and the affected side ratio, those in the OA groups tended to have a load on the unaffected side, while those in the KP groups had a load on the affected side. Therefore, it was suggested that there was the relationship of the OA and a knee pain of single-leg on the bilateral difference of ground reaction force in stepping.
We clarify the effect of combination of low-carbohydrate diet and resistance exercise training on physical characteristics and plasma concentrations of metabolites and hormones in humans. Intervention of low-carbohydrate diet and resistance exercise training were performed on 7 healthy men and 3 women (age 39.6 ± 7.0 year; BMI 25.1 ± 3.6 kg/m2) for 8 - 12 weeks. Physical characteristics and 106 test items including and blood concentrations of metabolites and hormones were measured before and after the intervention. The effects of intervention were analyzed by a paired t-test, in which multiple testing was corrected by the method of Storey (significant variation q <0.1). In both men and women, carbohydrate and energy intake per day were low, and protein intake per day was almost the same as the recommended dietary allowance. Because carbohydrate intake were limited (174 kcal), resulting in reduction of total energy (1186 kcal). After the intervention, body weight, BMI (Body Mass Index), fat mass, body fat, muscle mass and body water content significantly decreased, while muscle mass per body mass significantly increased. Glycine, 3-methyl histidine, inorganic phosphorous, urea nitrogen, urea nitrogen per creatinine, were significantly increased, while HbA1c, white blood cell count, β-aminoisobutyric acid, adrenalin, free T4, blood ammonia, γGTP, cholinesterase, and leptin were decreased.