Akira Tamaki

Low-intensity electrical muscle stimulation induces significant increases in muscle strength and cardiorespiratory fitness

Abstract The aim of this study was to investigate the effect of low-intensity exercise training using belt electrode skeletal muscle electrical stimulation on muscle strength and cardiorespiratory fitness in healthy subjects. Nineteen healthy subjects were allocated into control or intervention groups; in both groups the participants kept regular physical activity while the intervention group underwent 30 min B-SES training at 3–4 METs for four weeks. Knee extensor muscle strength and cardiorespiratory endurance during incremental exercise test were measured at baseline and after four weeks for all participants. The relative change of knee extensor muscle strength in the intervention group was significantly higher than control group (p < .05). Also, oxygen uptake at ventilator threshold and peak oxygen uptake during incremental exercise test significantly increased in the intervention group when compared with control group (p < .05). This study showed that prolonged low-intensity B-SES training resulted in significant increases in muscle strength and cardiorespiratory fitness in healthy subjects. Our present work suggested that B-SES training could assist patients who might have difficulty performing adequate voluntary exercise because of excessive obesity, orthopaedic problems and chronic diseases such as cardiovascular disease and type 2 diabetes. An intervention study conducted for such patients is strongly recommended.

Influence of thoracoabdominal movement on pulmonary function in patients with Parkinson's disease: comparison with healthy subjects.

Patients with Parkinsons disease (PD) may develop pulmonary dysfunction, but the pathogenesis remains unclear. We investigated a correlation between thoracoab dominal movements and pulmonary function in seven patients with PD and 14 healthy controls. We measured vital capacity (VC) and forced vital capacity (FVC) using an autospirometer, and measured chest and abdominal movements using a respiraory in ductance plethysmography by fixing transducers on the rib cage and umbilicus. Pa tients with PD had significantly decreased % VC (90.3 ± 17.1 vs 105.8 ± 13.9%), chest movement (271.3 ± 79.6 vs. 375.2 ± 126.7% VT) and abdominal movement (217.6 ± 93.5 vs. 247.4 ± 100.2% VT) with 100% VT being an average volume of chest and abdomen at rest during measurement of VC. Patients with PD also had sig nificantly decreased % FVC (74.4 ± 20.6 vs. 97.6 ± 14.1%), chest movement (246.2 ± 115.2 vs. 344.5 ± 126.4% VT) and abdominal movement (160.3 ± 105.6 vs 207.6 ± 104.7% VT) with 100% VT being an average volume of chest and abdomen at rest during forced maximal inspiration. Based on the results, we conclude that a reduction of % VC in patients with PD correlated with chest movements, while a reduction of % FVC correlated with ab dominal movement in patients with PD.

Comparison between stair-climbing test and six-minute walk test after lung resection using video-assisted thoracoscopic surgery lobectomy

[Purpose] Currently, the six-minute walk distance (6MWD) is used to evaluate exercise capacity in people following lung resection for non-small cell lung cancer. However, it is unclear whether the 6MWD can detect changes in cardiorespiratory fitness induced by exercise training or lung resection. Conversely, the stair-climbing test is used frequently for the preoperative evaluation of lung resection candidates. It is considered a sensitive method for detecting changes associated with training, but is not used to evaluate exercise capacity after lung resection. The purpose of this study was to compare the stair-climbing test and the six-minute walk test (6MWT) after lung resection. [Subjects and Methods] Fourteen patients undergoing lung resection completed the stair-climbing test and the 6MWT preoperatively, and one month postoperatively. The postoperative values and the percentage change in the stair-climbing test and the 6MWT were evaluated. [Results] The stair-climbing test results showed a significant deterioration at one month after lung resection; however, a significant change in the 6MWD was not observed. [Conclusion] When compared with the 6MWT, the stair-climbing test was more sensitive in detecting lung resection-induced changes in cardiorespiratory fitness.

Near falls predict substantial falls in older adults: a prospective cohort study

Little is known about the relationship between near falls and substantial falls in older adults. Clarifying this relationship would be helpful to assess fall risk in greater detail. The purpose of the present study was to clarify whether near falls predict future falls.

Effects of increased physical activity on body composition, physical functions, vascular functions, HR-QOL, and self-efficacy in community-dwelling elderly people

[Purpose] The objective of this study was to clarify the effects of increased number of steps on body composition, physical functions, vascular functions, health-related quality of life (HR-QOL) and self-efficacy in elderly people. [Subjects and Methods] The subjects were 47 elderly persons who resided in Port Island in the Chuo Ward of Kobe City in Hyogo Prefecture, Japan. After the calculation of the mean preintervention physical activity (PA), the subjects were instructed to increase their PA to a target baseline + 1,300 steps/day. Body composition, physical functions, vascular functions, HR-QOL, and self-efficacy were measured at baseline, after 3 and 6 months. These items were compared between a group that increased their PA and a group that did not. [Results] After 6 months, 26.1% of the subjects achieved the PA target. No significant improvements were observed in body composition, physical functions, vascular functions, or self-efficacy for either group after 3 and 6 months. However, the HR-QOL improved significantly after 6 months in the achievement group. [Conclusion] Although the intervention to increase PA did not produce significant improvements after 6 months in body composition, physical functions, vascular functions, or self-efficacy, the HR-QOL improved significantly during this relatively short period.

Diurnal effects of prior heat stress exposure on sprint and endurance exercise capacity in the heat

ABSTRACT Active individuals often perform exercises in the heat following heat stress exposure (HSE) regardless of the time-of-day and its variation in body temperature. However, there is no information concerning the diurnal effects of a rise in body temperature after HSE on subsequent exercise performance in a hot environnment. This study therefore investigated the diurnal effects of prior HSE on both sprint and endurance exercise capacity in the heat. Eight male volunteers completed four trials which included sprint and endurance cycling tests at 30 °C and 50% relative humidity. At first, volunteers completed a 30-min pre-exercise routine (30-PR): a seated rest in a temperate environment in AM (AmR) or PM (PmR) (Rest trials); and a warm water immersion at 40 °C to induce a 1 °C increase in core temperature in AM (AmW) or PM (PmW) (HSE trials). Volunteers subsequently commenced exercise at 0800 h in AmR/AmW and at 1700 h in PmR/PmW. The sprint test determined a 10-sec maximal sprint power at 5 kp. Then, the endurance test was conducted to measure time to exhaustion at 60% peak oxygen uptake. Maximal sprint power was similar between trials (p = 0.787). Time to exhaustion in AmW (mean±SD; 15 ± 8 min) was less than AmR (38 ± 16 min; p < 0.01) and PmR (43 ± 24 min; p < 0.01) but similar with PmW (24 ± 9 min). Core temperature was higher from post 30-PR to 6 min into the endurance test in AmW and PmW than AmR and PmR (p < 0.05) and at post 30-PR and the start of the endurance test in PmR than AmR (p < 0.05). The rate of rise in core temperature during the endurance test was greater in AmR than AmW and PmW (p < 0.05). Mean skin temperature was higher from post 30-PR to 6 min into the endurance test in HSE trials than Rest trials (p < 0.05). Mean body temperature was higher from post 30-PR to 6 min into the endurance test in AmW and PmW than AmR and PmR (p < 0.05) and the start to 6 min into the endurance test in PmR than AmR (p < 0.05). Convective, radiant, dry and evaporative heat losses were greater on HSE trials than on Rest trials (p < 0.001). Heart rate and cutaneous vascular conductance were higher at post 30-PR in HSE trials than Rest trials (p < 0.05). Thermal sensation was higher from post 30-PR to the start of the endurance test in AmW and PmW than AmR and PmR (p < 0.05). Perceived exertion from the start to 6 min into the endurance test was higher in HSE trials than Rest trials (p < 0.05). This study demonstrates that an approximately 1 °C increase in core temperature by prior HSE has the diurnal effects on endurance exercise capacity but not on sprint exercise capacity in the heat. Moreover, prior HSE reduces endurance exercise capacity in AM, but not in PM. This reduction is associated with a large difference in pre-exercise core temperature between AM trials which is caused by a relatively lower body temperature in the morning due to the time-of-day variation and contributes to lengthening the attainment of high core temperature during exercise in AmR.

Association between Pulmonary Function and Stair-Climbing Test Results after Lung Resection: A Pilot Study

Background The stair-climbing test was used to assess the exercise capacity before lung resection in subjects with lung cancer. However, few studies have systematically evaluated the role of this exercise methodology as a postoperative test. The aim of the present study was to assess whether the stair-climbing test findings reflect the postoperative decrease in pulmonary function. Methods Twenty subjects with non-small-cell lung cancer who underwent lung resection were enrolled in the study. Perioperative functional evaluation comprised the pulmonary function test, stair-climbing test, and 6-min walk distance test (6MWD). A correlation analysis was performed between the postoperative percentages of pulmonary function with respect to preoperative values and the exercise capacity. Results No correlation was noted between the percentage changes in pulmonary function and those in 6MWD. However, there was a significant correlation between the percentage changes in forced expiratory volume in 1 s and those in the altitude reached in the stair-climbing test (r=0.46, p < 0.05) and between the percentage changes in carbon monoxide lung diffusion capacity and those in the altitude (r=0.54, p < 0.05). Conclusions The stair-climbing test findings might be effective at detecting changes in exercise capacity induced by postoperative decrease in pulmonary function.

Physical activity combined with resistance training reduces symptoms of frailty in older adults: A randomized controlled trial

INTRODUCTION Increased physical activity (PA) is a crucial factor in the prevention of physical deterioration, and resistance training (RT) is also a common and effective intervention for older adults. However, the effects of PA as an adjunct to RT on frailty status remains unclear; therefore, we clarified the effect of a PA intervention with feedback, as an adjunct to resistance strength training, on the physical and mental outcomes of frail older adults. MATERIALS AND METHODS We employed a randomized controlled trial. Community-dwelling frail older adults in Japan were recruited to participate. Forty-one participants (mean age 81.5) were randomly assigned to engage in a resistance training with PA (RPA group) or RT group for six months. Frailty status and frailty scores, which were measured according to the Cardiovascular Health Study criteria-muscle strength, mobility, instrumental activities of daily living, and health-related quality of life-were assessed. RESULTS Participants in the RPA group exhibited a significant increase in light-intensity PA, the number of steps taken daily (p < 0.05), and lower-limb muscle strength (p < 0.05) and a significant decrease in frailty scores. However, pre- and postintervention frailty status, instrumental activities of daily living, and health-related quality of life did not differ significantly. CONCLUSIONS Implementation of a PA intervention as an adjunct to RT is feasible, as it reduced frailty scores and increased lower-limb muscle strength and mobility in older adults with frailty symptoms.

Influence of gender on muscle fatigue during dynamic knee contractions

PURPOSE The purpose was to compare quadriceps muscle fatigue and change in surface electromyogram (sEMG) spectral power, muscle thickness, and peak torque (normalized by body weight) in men and women during isokinetic knee contractions. METHODS Nineteen healthy volunteers (10 men, 9 women) participated. The volunteers performed 32 consecutive maximal isokinetic knee contractions for peak torque and muscle fatigue index (FI). The sEMG data were analyzed using wavelet analysis for median frequency (MF). Muscle thickness was measured using ultrasonography. RESULTS Men had a significantly higher FI, peak torque (Nm/kg), muscle thickness than women (p<0.05). A significant linear decreased MF slope in the vastus lateralis was observed (p<0.05) in men than in women. There was no significant difference in MF slope in the vastus medialis between men and women. CONCLUSION During muscle fatigue assessment, men had a significantly greater muscle thickness, knee extension peak torque, and a higher decrease of MF slope than women. Our results indicate that specific muscle fatigue observed during repeated muscle knee contractions is significantly influence by gender and affects MF slope, knee extension peak torque, and muscle thickness.

Effect of Locomotor Respiratory Coupling Induced by Cortical Oxygenated Hemoglobin Levels During Cycle Ergometer Exercise of Light Intensity.

This study aimed to clarify the effects of locomotor-respiratory coupling (LRC) induced by light load cycle ergometer exercise on oxygenated hemoglobin (O2Hb) in the dorsolateral prefrontal cortex (DLPFC), supplementary motor area (SMA), and sensorimotor cortex (SMC). The participants were 15 young healthy adults (9 men and 6 women, mean age: 23.1 ± 1.8 (SEM) years). We conducted a task in both LRC-inducing and LRC-non-inducing conditions for all participants. O2Hb was measured using near-infrared spectroscopy. The LRC frequency ratio during induction was 2:1; pedaling rate, 50 rpm; and intensity of load, 30 % peak volume of oxygen uptake. The test protocol included a 3-min rest prior to exercise, steady loading motion for 10 min, and 10-min rest post exercise (a total of 23 min). In the measurement of O2Hb, we focused on the DLPFC, SMA, and SMC. The LRC frequency was significantly higher in the LRC-inducing condition (p < 0.05). O2Hb during exercise was significantly lower in the DLPFC and SMA, under the LRC-inducing condition (p < 0.05). The study revealed that even light load could induce LRC and that O2Hb in the DLPFC and SMA decreases during exercise via LRC induction.