Abstract :
Introduction: Muscle fiber composition and fatigue characteristics are different in strength or endurance trained elite athletes, this may be a result of muscle adaptation to specific training loads. EMG power spectra can be used to study these differences.
Objective: Study the effect of long-term training on the muscle fatigue and fiber composition.
Methods: SEMG was recorded in country’s elite athletes who were either endurance (Marathoners/ Long distance runners, En; n=20) or strength (Weight lifters / Throwers, St; n=20) trained for past > 5 years. The fall in EMG median frequency (MDF) of two upper body (Biceps Brachii; BB & Triceps; TR) and two lower body (Vastus Lateralis; VL & Biceps Femoris; BF) muscles, during 80% MVC isometric contraction was used to assess fatigability and thus the predominant muscle fiber type. Similar data was also collected in untrained controls (Un; n=20).
Results: MDF showed no significant fall (p > 0.05) during the task in TR and VL in all the groups, indicating higher proportion of type I fibers and inconsequent influence of type of training. BB & BF (St & Un only) MDF fell significantly (p< 0.05) during the task indicative of more type II fibers. BF MDF in En group though showed a decrease but it was not statistically significant (p > 0.05).
Conclusion: The results indicate higher proportion type I fibers in hamstrings (BF) of Endurance trained athletes when compared to other subjects, suggestive of its adaptability to long-term endurance training.
Keyword :
Strength, Endurance, Fatigue, SEMG