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PDF Mechanism for Attenuation of Muscle Hypertrophic Effect Per Exercise Sessions in Continuous Resistance Training

【Supercategory:7. DESCENTE SPORTS SCIENCE Subcategory:7.42 Vol.42

 ABSTRACT

 Resistance exercise training is effective for muscle hypertrophy, but continuous training gradually attenuates the hypertrophic effect per exercise session. Inactivation of mechanistic target of rapamycin complex 1( mTORC1, which plays role in protein synthesis in skeletal muscle) after resistance exercise is involved in the mechanism. Meanwhile, mTORC1 accounts for not only muscle protein anabolic systems but also muscle protein catabolic systems. Here, we investigated the bouts dependent changes in the ubiquitin-proteasome system and autophagy-lysosome system related factors, which are main protein catabolic systems in skeletal muscle, after resistance exercise. Male Sprague-Dawley rats were resistance-exercised 10 bouts with interval of 48 hours between bouts. The resistance exercise consisted of 50 repetitions of maximal isometric contractions of the right gastrocnemius muscle, elicited by transcutaneous electrical stimulation under anesthesia. Immediately (0h post-RE) and 3h (3h post-RE) after the 1st and 10th exercise bouts, muscle samples were collected. The left gastrocnemius muscles were served as internal control. At 0h post-RE, the expression of ubiquitinated proteins decreased despite the number of exercise bouts. At 3h post-RE, the expression of ubiquitinated proteins increased despite the number of exercise bouts. At 0h post-RE, the expression of LC3-II (an indicator of autophagosome formation) did not change at both number of exercise bouts. At 3h post-RE, the expression of LC3-II decreased despite the number of exercise bouts. These results suggest that the response of the ubiquitin-proteasome system and autophagy-lysosome system does not change in continuous resistance exercise training, and the changes in the response of protein catabolic systems is not involved in the blunting of muscle hypertrophic effect.

DECENTE SPORTS SCIENCE Vol.42/The DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE
Researcher Junya Takegaki*1, Kohei Sase*2
University or institution *1 Ritsumeikan University, *2 Faculty of Sport and Health Science, Ritsumeikan University

Keywords

resistance exercise, mTOR complex 1, muscle protein breakdown, ubiquitin, autophagy