Exercise time and circadian rhythm may impact maximal skeletal muscle hypertrophy

2018 Fiscal Year Final Research Report

• Project/Area Number: 17K13192
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Sports science
• Research Institution: Juntendo University
• Principal Investigator: CHANG SHUOWEN 順天堂大学, スポーツ健康科学部, 博士研究員 (20783913)
• Research Collaborator: NATIO Hisashi ; YOSHIHARA Toshinori
• Project Period (FY): 2017-04-01 – 2019-03-31
• Keywords: サーカディアンリズム / 筋肥大 / 筋タンパク質 / トレーニング / ホルモン

Outline of Final Research Achievements

This study aimed to examine whether exercise at different times of the day influences skeletal muscle hypertrophy in rats. Our data revealed that activation of p70S6K immediately after eccentric-exercise was higher in the inactive phases than in the active phases. Moreover, the training effect (muscle hypertrophy) in response to 8 weeks of eccentric-training was significantly higher in the inactive phase than that found in the active phases. Although the specific mechanism associated with the differential effects of exercising at different times of the day is still unclear, we suggest that it may be mediated by the regulation of p70S6K phosphorylation via the glucocorticoid receptor. Our data demonstrated that eccentric-exercise at different times of day may affect the degree of muscle hypertrophy. This is a novel insight that may point to a potential influence of circadian rhythms in determining exercise effectiveness for gaining muscle mass and size.

Free Research Field

運動生理学

Academic Significance and Societal Importance of the Research Achievements

本研究は、骨格筋の肥大に関わる細胞内シグナル伝達の活性化には、筋組織特異的なサーカディアンリズムが関与しており、同一の運動を実施しても、その時間帯によって獲得できる効果が異なることを示唆するものである。これらの成果は、競技力の向上やリハビリテーションの領域において、トレーニング効果を最大限に発揮するための最適な運動プログラムの立案に貢献できると考えられる。