Secondary Logo

Journal Logo

Institutional members access full text with Ovid®

Resistance Exercise–induced Changes in Muscle Phenotype Are Load Dependent

LIM, CHANGHYUN1,2; KIM, HYO JEONG3; MORTON, ROBERT W.1; HARRIS, ROGER4; PHILLIPS, STUART M.1; JEONG, TAE SEOK5; KIM, CHANG KEUN2,6

Medicine & Science in Sports & Exercise: December 2019 - Volume 51 - Issue 12 - p 2578–2585
doi: 10.1249/MSS.0000000000002088
APPLIED SCIENCES
Buy
SDC

Introduction Lower-load (LL), higher-repetition resistance exercise training (RET) can increase muscle mass in a similar degree as higher-load (HL), lower-repetition RET. However, little is known about how LL and HL RET modulate other aspects of the RET phenotype such as satellite cells, myonuclei, and mitochondrial proteins. We aimed to investigate changes in muscle mass, muscle strength, satellite cell activity, myonuclear addition, and mitochondrial protein content after prolonged RET with LL and HL RET.

Methods We recruited 21 young men and randomly assigned them to perform 10 wk RET (leg press, leg extension, and leg curl) three times per week with the following conditions: 80FAIL (80% one-repetition maximum [1RM] performed to volitional fatigue), 30WM (30%1RM with volume matched to 80FAIL), and 30FAIL (30%1RM to volitional fatigue). Skeletal muscle biopsies were taken from the vastus lateralis pre- and post-RET intervention.

Results After 10 wk of RET, only 30FAIL and 80FAIL showed an increase in peak torque and type I fiber cross-sectional area (P < 0.05). Moreover, only 30FAIL resulted in a significant decrease in the myonuclear domain of type II muscle fibers and an increase in mitochondrial proteins related to autophagy, fission, and fusion (all P < 0.05).

Conclusion We discovered that LL RET was effective at increasing the content of several mitochondrial proteins. Similar to previous research, we found that changes in muscle mass and strength were independent of load when repetitions were performed to volitional fatigue.

1Department of Kinesiology, McMaster University, Ontario, CANADA

2Human Physiology, Korea National Sport University, Seoul, SOUTH KOREA

3Aging Physiology, Korea National Sport University, Seoul, SOUTH KOREA

4Junipa Ltd., Newmarket, Suffolk, UNITED KINGDOM

5SPIK Sport Medicine Clinic and Performance Centre, Seoul, SOUTH KOREA

6Exercise and Metabolism Research Centre, Zhejiang Normal University, Jinhua, CHINA

Address for correspondence: Chang Keun Kim, Ph.D., Human Physiology, Korea National Sport University, 88-15 Oryun-dong, Songpa-gu, Seoul, South Korea; E-mail: ckkim@knsu.ac.kr.

Submitted for publication March 2019.

Accepted for publication June 2019.

Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s Web site (www.acsm-msse.org).

Online date: July 15, 2019

© 2019 American College of Sports Medicine