Striking muscle adaptations induced by volume-dependent repeated bouts of low-intensity eccentric exercise of the elbow flexors

Trevor C. Chen*, Wei Chin Tseng, Hsin Lian Chen, Kuo Wei Tseng, Tai Ying Chou, Yuh Chuan Huang, Kazunori Nosaka

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)

Abstract

We investigated the effects of repeating 30 low-intensity eccentric contractions with a dumbbell corresponding to 10% maximal isometric strength (10%EC) on muscle strength and hypertrophy, and muscle damage after 30 maximal eccentric contractions (MaxEC) of the elbow flexors. Young men were placed into 1 of 3 experimental groups that performed 10%EC either once, twice a week for 4 (8 bouts) or 8 weeks (16 bouts) before MaxEC, or a control group that performed 2 bouts of MaxEC separated by 2 weeks (n = 13/group). Repeating 16 bouts of 10%EC increased (P < 0.05) maximal voluntary contraction strength (30 6 21%) and muscle thickness (4.2 6 2.3%) greater than 8 bouts (16 6 4%, 1.9 6 1.3%). Changes in the muscle damage markers after MaxEC were smaller (P < 0.05) for the experimental groups than the control group, and the magnitude of muscle damage protection was greater (P < 0.05) after 16 bouts (65 6 30%) than 8 bouts (55 6 33%), followed by 1 bout (34 6 27%). The protection by 16 bouts was similar (P = 0.81) to that shown by the second MaxEC of the control group. These results showed that 10%EC produced potent muscle adaptation effects accumulatively and conferred muscle damage protection, but 1 bout of 10%EC was still effective for conferring approximately 20% of the protection of that by 16 bouts. Novelty: Repeating low-intensity eccentric exercise induces large increases in muscle strength and hypertrophy. Low-intensity eccentric exercise protects muscle damage induced by maximal eccentric contractions, and the protection is reinforced by repeating it. These are especially beneficial for individuals who are frail and cannot tolerate high-intensity resistance training.

Original languageEnglish
Pages (from-to)897-905
Number of pages9
JournalApplied Physiology, Nutrition and Metabolism
Volume46
Issue number8
DOIs
Publication statusPublished - 2021

Keywords

  • Delayed onset muscle soreness
  • Dumbbell
  • Elbow flexors
  • Maximal voluntary isometric contraction strength
  • Plasma creatine kinase activity
  • Protective effect

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Physiology
  • Nutrition and Dietetics
  • Physiology (medical)

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