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E-34 Free Communication/Poster - Muscle Adaptations, Atrophy, and Hypertrophy Friday, June 2, 2017, 7: 30 AM - 12: 30 PM Room: Hall F

Effects Of Time-of-day Specific Resistance Training On Muscle Strength And Muscular Il-6-associated Signaling In Male Rats

2691 Board #211 June 2 11

00 AM - 12

30 PM

Yu, Szu-Hsien1; Lin, Shueh-I1; Cheng, Shih-Chang1; Chi, Chung-Pu2; Kuo, Chia-Hua FACSM3

Author Information
Medicine & Science in Sports & Exercise: May 2017 - Volume 49 - Issue 5S - p 769
doi: 10.1249/01.mss.0000519048.18806.65
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PURPOSE: Muscle mass and strength play an important role in athletic sports and health promotion. Although resistance training (RT) is known to be effective for muscle mass improvement, the optimal daily timing of RT and feeding has not yet been determined. The purposes of the present study are to investigate the best daily timing of RT for the muscle hypertrophy in male rats.

METHODS: In study I, SD rats were divided into Control (C, non-exercise), Early (E, beginning of active phase, 8:00) and Late (L, end of active phase, 17:00). Rats of exercise groups (E and L) were asked to perform RT by climbing for 10 weeks in beginning and end of active phase respectively. Climbing strength and weight of flexor hallucis longus (FHL) and flexor digitorum profundus (FDP) was determined after 10 weeks training. In study II, rats were divided into E (Early) and L (Late) groups and were performed an acute RT by climbing. FDP muscle samples were obtained 2, 6 and 24 hours after RT.

RESULTS: In study I, we observed that 10 weeks RT improve muscle strength, muscle mass and myofiber cross sectional area (CSA), but these training effects do not show any significant difference between E and L groups. In study II, acute RT in the evening induced more plasma testosterone/cortisol and IL-6, and muscular IL-6 associated signaling such as phosphorylation of STAT1 and STAT3 compared to training in the morning.

CONCLUSIONS: we suggest that resistance exercise-induced IL-6 signal in skeletal muscle is not the main source of 10 weeks resistace training adaptation.

© 2017 American College of Sports Medicine