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Updated: Aug 5, 2026
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Induction and Assessment of Exertional Skeletal Muscle Damage in Humans
Published on: December 11, 2016
Serial sarcomerogenesis does not contribute to the initial repeated bout effect in skeletal muscle
Ethan Vlemmix1, Avery Hinks1, Geoffrey A Power1
1Department of Human Health and Nutritional Sciences, College of Biological Sciences, University of Guelph, 50 Stone Road East, Guelph, Ontario, Canada.
Journal of Biomechanics
|May 22, 2025
Summary
The repeated bout effect (RBE) protects muscles after eccentric exercise, but adding sarcomeres in series (sarcomerogenesis) does not initially contribute to this protective adaptation. This study found no increase in serial sarcomere number following damaging eccentric exercise in rats.
Area of Science:
- Exercise Physiology
- Muscle Biology
- Skeletal Muscle Adaptation
Background:
- Eccentric exercise can impair neuromuscular function.
- The repeated bout effect (RBE) confers protection against subsequent eccentric exercise bouts.
- Sarcomerogenesis (addition of sarcomeres in series) has been hypothesized to contribute to the RBE by reducing muscle strain.
Purpose of the Study:
- To investigate if a single bout of damaging eccentric exercise induces sarcomerogenesis.
- To determine if induced sarcomerogenesis contributes to the protective effect observed in the RBE.
- To examine the role of serial sarcomere number changes in the initial RBE.
Main Methods:
- Used an in-vivo rat model (Sprague-Dawley rats).
- Induced maximal eccentric contractions of plantar flexors to impair mechanical function.
- Assessed serial sarcomere number (SSN) via laser diffraction and torque production after initial and repeated exercise bouts.
Main Results:
- A single eccentric exercise bout caused long-lasting impairments in torque production.
- A robust RBE was observed, with torque measures recovering by 2 days post-exercise.
- No significant difference in SSN was found between control and exercised legs, indicating sarcomerogenesis did not occur.
Conclusions:
- Sarcomerogenesis is not a primary initial mechanism contributing to the repeated bout effect (RBE).
- The muscle demonstrates a protective adaptation (RBE) following damaging eccentric exercise independent of serial sarcomere addition.
- Further research is needed to identify the mechanisms underlying the RBE.
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