Soccer-specific fatigue and eccentric hamstrings muscle strength

Context: Epidemiologic findings of higher incidences of hamstrings muscle strains during the latter stages of soccer match play have been attributed to fatigue. Objective: To investigate the influence of soccer-specific fatigue on the peak eccentric torque of the knee flexor muscles. Design: Descriptive laboratory study. Setting: Controlled laboratory environment. Patients or Other Participants: Ten male professional soccer players (age = 24.7 ± 4.4 years, mass = 77.1 ± 8.3 kg, VO_2max = 63.0 ± 4.8 mL·kg^-1·min^-1). Intervention(s): Participants completed an intermittent treadmill protocol replicating the activity profile of soccer match play, with a passive halftime interval. Before exercise and at 15-minute intervals, each player completed isokinetic dynamometer trials. Main Outcome Measure(s): Peak eccentric knee flexor torque was quantified at isokinetic speeds of 180° · s^-1, 300° · s^-1, and 60° · s^-1, with 5 repetitions at each speed. Results: Peak eccentric knee flexor torque at the end of the game (T_300eccH105 = 127 ± 25 Nm) and at the end of the passive halftime interval (T_300eccH60 = 133 ± 32 Nm) was reduced relative to T_300eccH00 (167 ± 35 Nm, P < .01) and T300eccH15 (161 ± 35 Nm, P = .02). Conclusions: Eccentric hamstrings strength decreased as a function of time and after the halftime interval. This finding indicates a greater risk of injuries at these specific times, especially for explosive movements, in accordance with epidemiologic observations. Incorporating eccentric knee flexor exercises into resistance training sessions that follow soccerspecific conditioning is warranted to try to reduce the incidence or recurrence of hamstrings strains.