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Exercise-induced skeletal muscle growth. Hypertrophy or hyperplasia?
Sports Medicine (Auckland, N.Z.)
|May 1, 1986
Summary
Skeletal muscle growth in humans primarily involves fiber enlargement, not new fiber creation. While some studies suggest hyperplasia, evidence remains inconclusive, requiring further research into satellite cell development.
Area of Science:
- Exercise physiology
- Muscle biology
- Cellular adaptation
Background:
- Postnatal skeletal muscle growth is typically attributed to myofiber hypertrophy.
- Limited historical and regeneration-based evidence suggests potential for muscle fiber splitting or hyperplasia.
Purpose of the Study:
- To review evidence for exercise-induced skeletal muscle hyperplasia in humans.
- To critically evaluate animal models used to study muscle growth.
- To identify methodological limitations in current research.
Main Methods:
- Review of existing literature on human and animal models of muscle growth.
- Analysis of methodological criticisms regarding fiber counting and cross-sectional area measurements.
- Discussion of animal models: compensatory hypertrophy, stretch-induced hypertrophy, and weight lifting.
Main Results:
- Indirect evidence for exercise-induced hyperplasia in humans is methodologically flawed.
- Animal models provide insights but have limitations.
- Errors in fiber number estimation are common due to fiber termination and muscle architecture.
Conclusions:
- Exercise-induced skeletal muscle hyperplasia in humans is not yet substantiated.
- New fiber formation, if it occurs, may involve satellite cell differentiation.
- Further rigorously controlled studies are needed to definitively answer questions about muscle hyperplasia.