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Relationships between leg muscle fiber type distribution and leg exercise performance
International Journal of Sports Medicine
|August 1, 1981
Summary
Muscle fiber type composition significantly impacts athletic performance in trained individuals, influencing both short-term power and endurance. This correlation was not observed in sedentary subjects, suggesting training status is key.
Area of Science:
- Exercise Physiology
- Sports Science
- Human Performance
Background:
- Muscle fiber type composition is a known determinant of athletic capabilities.
- Understanding the relationship between fiber types and specific performance metrics is crucial for optimizing training.
Purpose of the Study:
- To investigate the impact of muscle fiber type composition on aerobic and anaerobic exercise performance.
- To determine if correlations between fiber type and performance differ between trained athletes and sedentary individuals.
Main Methods:
- Muscle biopsies were taken from the vastus lateralis of 29 healthy males (sedentary, students, runners).
- Subjects performed a battery of tests including cycle ergometry, isokinetic leg exercise, and sprint/endurance runs (40m, 300m, 2000m).
- Muscle fiber composition (% fast twitch fibers) was correlated with performance outcomes.
Main Results:
- Significant correlations (P < 0.001) were found between % fast twitch (FT) fibers and laboratory performance tests (peak power, torque) in trained subjects, but not in sedentary individuals.
- In trained subjects, % FT fibers positively correlated with 40-m sprint speed and negatively with 2000-m run speed (P < 0.001).
- No significant correlations were observed for sedentary subjects.
Conclusions:
- Muscle fiber type composition is a significant factor in both short-term and endurance exercise performance in trained males.
- The influence of fiber type on performance may be specific to individuals with a trained status and not generalizable to the sedentary population.