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PURPOSE: Previous studies have reported that low-load high-repetition (LLHR) resistance exercise can induce muscle hypertrophy to a similar extent as high-load low-repetition (HLLR). However, it is unclear which mechanical stress, such as exercise intensity, contraction number, and/or total work volume and which molecular mechanisms underpin the greater relative muscle hypertrophy after LLHR exercise.METHODS: Sprague-Dawley rats (12 weeks, N=35) were randomly allocated into control (Con, n=7), low-load low-repetition (LLLR, n=7), low-load medium-repetition (LLMR, n=7), LLHR (n=7), and HLLR (n=7) resistance exercise groups. They performed a ladder climbing exercise to evaluate the effect of exercise intensity, contraction number and work volume on the activation of satellite cells and protein synthesis signaling pathway.RESULTS: The number of active satellite cells and the phosphorylation of mTOR, p70S6K, ERK, and p38 were increased after LLHR and HLLR exercise (pp

PURPOSE This study was performed to investigate the effect of maternal exercise on cardiac and skeletal muscle telomere length and telomere repeat binding factor 2 (TRF2) in rat offspring. METHODS Sprague-Dawley rats (10 wk, N=21) were randomly assigned into control (CON), exercise during pregnancy (ExD), and exercise before and during pregnancy (ExBD) groups. Maternal training was performed on a rodent treadmill for 1 hour at 60-75% VO2max for 3 weeks (5 d/w) before and during pregnancy respectively. The offspring were sacrificed at birth and telomere length and TRF2 expression were measured with cardiac and skeletal muscle samples. RESULTS CON group had significantly longer telomere length (p=.011, p=.049) and higher TRF2 expression (p=.011, p=.002) than other two groups in skeletal muscle of offspring. In the cardiac muscle, CON group showed longer telomere length compared with ExD group in offspring (p=.001). CONCLUSIONS Intense maternal exercise before or during pregnancy may negatively affect their new offspring’s cardiac and skeletal muscle telomere length and TRF2 expression.