Objectives: To investigate the knee flexor torque-angle curve after hamstring strain injury using different muscle action types and angular velocities.
Design: Cross-sectional.
Setting: Controlled laboratory.
Participants: Thirteen collegiate athletes injured hamstring strain (21.0 ± 0.8 years; 173.9 ± 6.5 cm; 70.1 ± 10.5 kg).
Main outcome measures: Concentric and eccentric knee flexor torque was measured at 60 & 300°/sec. Peak torque and average torque every 10° were determined from torque-angle curve and injured side was compared with non-injured side.
Results: No significant differences were found in the concentric muscle actions. However, the eccentric peak torque was significantly lower on the injured side at 60°/sec (p = 0.048) and at 300°/sec (p = 0.002). The average eccentric torque was significantly lower on the injured side at 60°/sec from 10° to 20° of knee flexion (p = 0.012-0.018) and at 300°/sec from 10° to 60° of knee flexion (p = 0.005-0.049).
Conclusion: The knee flexor torque-angle curve changes with eccentric muscle action after hamstring injury. Eccentric torque declines were close to full knee extension at 60°/sec and a wide range of knee flexion at 300°/sec. The assessment and rehabilitation of eccentric hamstring strength may be important to consider the effect of the angular velocity after hamstring strain injury.
Keywords: dynamometer; eccentric muscle action; hamstring injury; high angular velocity.
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