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- Author or Editor: Tomohiro Yasuda x
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The purpose of this study was to examine the anthropometric, body composition, and somatotype characteristics of Japanese young women and to focus on normal-weight obesity syndrome and sarcopenia diagnosis criteria.
A total of 124 Japanese university freshmen women were measured at body mass index (BMI), percent body fat and skeletal muscle index (SMI), usual gait test, and handgrip strength. The subjects were divided into obesity (≥30% body fat; BMI: ≥25.0 kg/m2), normal-weight obesity (≥30% body fat; BMI: 18.5–24.9 kg/m2), sarcopenia (handgrip, <18 kg; gait speed: ≤0.8 m/s; SMI: <5.7 kg/m2), or presarcopenia (SMI: <5.7 kg/m2). There were no subjects below the sarcopenia diagnosis criteria in usual gait speed, but not for handgrip (0.8%) and SMI (36.3%).
The prevalence of presarcopenia group (36.3%) is higher than in the normal-weight obesity (16.9%) and obesity (4.8%) groups. Anthropometry and sarcopenia diagnosis assessments were significantly higher in normal-weight obesity and standard groups compared with presarcopenia group.
The number of young women was higher in the presarcopenia group than in the normal-weight obesity group, suggesting that the improvement of intrinsic skeletal muscle mass rather than fat mass is important for Japanese young women.
Low-intensity resistance exercise with blood flow restriction (BFR) has been shown to induce a prominent increase in muscle activation in response to muscle fatigue. However, the magnitude of muscle fatigue between continuous (Con-BFR) and intermittent BFR (Int-BFR, BFR only during exercise) is currently unknown. We examined the effect of Con-BFR or Int-BFR on muscle activation during exercise. Unilateral arm curl exercise (20% of one-repetition maximum, four sets, 30 sec rest period between sets) was performed without (CON) or with Con-BFR or Int-BFR. During BFR conditions, the cuff was inflated to 160 mmHg on the proximal region of testing arm. Surface electromyography (EMG) was recorded from the biceps brachii muscle, and integrated EMG (iEMG) was analyzed. During the exercise, iEMG increased progressively in Con-BFR and Int-BFR and both conditions were greater (p < 0.05) than CON at the 3rd and 4th set. However, there were no differences (p > 0.05) in iEMG between Con-BFR and Int-BFR during exercise (∼2.45 and ∼2.40 times, respectively). Thus, the magnitude of increase in muscle activation may be similar between Con-BFR and Int-BFR when BFR exercise was performed at a high level of cuff pressure intensity.
Low-intensity blood-flow restriction (BFR) resistance training significantly increases strength and muscle size, but some studies report it produces exercise-induced muscle damage (EIMD) in the lower body after exercise to failure.
To investigate the effects of a pre-set number of repetitions of upper body concentric and eccentric exercise when combined with BFR on changes in EIMD.
Ten young men had arms randomly assigned to either concentric BFR (CON-BFR) or eccentric BFR (ECC-BFR) dumbbell curl exercise (30% one-repetition maximum (1-RM), 1 set of 30 repetitions followed by 3 sets of 15 repetitions). Maximal isometric voluntary contraction force (MVC), muscle thickness (MTH), circumference, range of motion (ROM), ratings of perceived exertion (RPE), and muscle soreness were measured before, immediately after, and daily for 4 days post-exercise.
MVC decreased by 36% for CON-BFR and 12% for ECCBFR immediately after exercise but was not changed 1–4 days post-exercise (p > 0.05). Only CON-BFR had significant changes in MTH and circumference immediately after exercise (p < 0.05). Muscle soreness was observed in the ECC-BFR arm at 1 and 2 days after exercise.
Low-intensity ECC-BFR produces significant muscle soreness at 24 h but neither ECC-BFR nor CON-BFR exercise produces significant changes in multiple indices of EIMD.