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Segmental muscle fiber lesions after repetitive eccentric contractions
1Department of Hand Surgery, Sahlgrenska University Hospital, University of Göteborg, Göteborg, Sweden. jan.friden@orthop.gu.se
Cell and Tissue Research
|June 23, 1998
Summary
Repetitive eccentric contractions cause muscle damage by disrupting the cytoskeleton and cell integrity. This leads to fiber swelling and hypercontraction, initiating a cascade of muscle repair events.
Area of Science:
- Muscle physiology
- Cellular biology
- Sports medicine
Background:
- Eccentric contractions are known to cause muscle damage.
- The precise sequence of cellular events following eccentric exercise is not fully understood.
Purpose of the Study:
- To investigate the temporal sequence of cellular changes in skeletal muscle following repetitive eccentric contractions.
- To elucidate the role of cytoskeletal proteins and cellular integrity in muscle injury and repair.
Main Methods:
- Immunohistochemical and electron-microscopic analyses were performed on rabbit extensor digitorum longus muscles.
- Samples were collected at various time points (1 h, 1 day, 3, 7, and 28 days) post-exercise.
Main Results:
- Loss of the cytoskeletal protein desmin was the earliest sign of injury.
- Desmin-negative fibers showed positive staining for plasma fibronectin, indicating compromised cellular integrity.
- Muscle fibers increased in size from 1-7 days post-exercise, with hypercontraction and Z-disk streaming observed.
- A sequence of cytoskeletal disruption, loss of myofibrillar registry, and cell integrity loss was identified.
Conclusions:
- Cytoskeletal disruption and loss of cell integrity are early events in eccentric contraction-induced muscle injury.
- Hypercontraction and Z-disk streaming contribute to the observed fiber morphology changes.
- The findings provide a detailed timeline of cellular events following muscle damage, crucial for understanding muscle repair mechanisms.