Authors:Robert S. Thiebaud, Tomohiro Yasuda, Jeremy P. Loenneke and Takashi Abe
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.
Authors:Riki Ogasawara, Robert S. Thiebaud, Jeremy P. Loenneke, Mark Loftin and Takashi Abe
The purpose of this study was to investigate the time course of hypertrophic adaptations in both the upper arm and trunk muscles following high-intensity bench press training. Seven previously untrained young men (aged 25±3 years) performed free-weight bench press training 3 days (Monday, Wednesday and Friday) per week for 24 weeks. Training intensity and volume were set at 75% of one repetition maximum (1-RM) and 30 repetitions (3 sets of 10 repetitions, with 2–3 min of rest between sets), respectively. Muscle thickness (MTH) was measured using B-mode ultrasound at three sites: the biceps and triceps brachii and the pectoralis major. Measurements were taken a week prior to the start of training, before the training session on every Monday and 3 days after the final training session. Pairwise comparisons from baseline revealed that pectoralis major MTH significantly increased after week-1 (p=0.002), triceps MTH increased after week-5 (p=0.001) and 1-RM strength increased after week-3 (p=0.001) while no changes were observed in the biceps MTH from baseline. Significant muscle hypertrophy was observed earlier in the chest compared to that of the triceps. Our results indicate that the time course of the muscle hypertrophic response differs between the upper arm and chest.
Authors:Takashi Abe, Yu Yaginuma, Eiji Fujita, Robert S. Thiebaud, Masashi Kawanishi and Takuya Akamine
To test the hypothesis that sit-up performance is associated with sarcopenia classification measures, 93 older women aged 53–78 years were divided into three groups based on achieved repetitions (30 s) for the sit-up performance test: Group 0 (G 0, n = 33) performed 0 repetitions, Group 1–9 (G 1–9, n = 30) performed between 1 and 9 repetitions, and Group 10+ (G 10+, n = 30) performed over 10 repetitions. Dual-energy X-ray absorptiometry-derived appendicular lean soft tissue mass (aLM), handgrip strength (HGS), usual walking speed, and chair stand were measured, and low muscle mass (aLM index) and poor physical function were defined according to previous studies. Age and body mass index were similar among the three groups. HGS was higher in G 10+ compared with G 0. The prevalence rate of low muscle mass was 30% for G 0, 20% for G 1–9, and 3% for G 10+. Low HGS was observed in both G 0 (24%) and G 1–9 (20%), but not in G 10+. Only two persons in G 0 were classified as slow walking speed. Our results suggest that sit-up performance may be a useful indicator to determine the extent of sarcopenia because low muscle mass and poor function were almost non-existent in individuals who could perform over 10 sit-ups.
Authors:Robert Thiebaud, J.P. Loenneke, C.A. Fahs, D. Kim, X. Ye, T. Abe, K. Nosaka and M.G. Bemben
Discrepancies exist whether blood flow restriction (BFR) exacerbates exercise-induced muscle damage (EIMD). This study compared low-intensity eccentric contractions of the elbow flexors with and without BFR for changes in indirect markers of muscle damage. Nine untrained young men (18–26 y) performed low-intensity (30% 1RM) eccentric contractions (2-s) of the elbow flexors with one arm assigned to BFR and the other arm without BFR. EIMD markers of maximum voluntary isometric contraction (MVC) torque, range of motion (ROM), upper arm circumference, muscle thickness and muscle soreness were measured before, immediately after, 1, 2, 3, and 4 days after exercise. Electromyography (EMG) amplitude of the biceps brachii and brachioradialis were recorded during exercise. EMG amplitude was not significantly different between arms and did not significantly change from set 1 to set 4 for the biceps brachii but increased for the brachioradialis (p ≤ 0.05, 12.0% to 14.5%) when the conditions were combined. No significant differences in the changes in any variables were found between arms. MVC torque decreased 7% immediately post-exercise (p ≤ 0.05), but no significant changes in ROM, circumference, muscle thickness and muscle soreness were found. These results show that BFR does not affect EIMD by low-intensity eccentric contractions.