Effect of Acute Low-load High-repetition Resistance Exercise on Protein Synthetic Signaling Pathway and Satellite Cell Activation in Skeletal Muscle of Rats

• Main Authors: Chang-Hyun Lim, Chang-Keun Kim
• Format: Article
• Language: Korean
• Published: The Korean Society of Exercise Physiology 2020-02-01
• Series: 운동과학
• Subjects: skeletal muscle; hypertrophy; resistance exercise; exercise intensity; protein synthesis
• Online Access: http://www.ksep-es.org/upload/pdf/es-29-1-77.pdf

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 (p<.005). However, phosphorylation of 4E-BP1 was only increased after the LLHR exercise (p<.05). CONCLUSIONS Acute low load exercise accompanied by high total work volume may activate muscle protein synthesis mechanisms for hypertrophy similar to high load resistance exercise.