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 x kg(-1) x 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 degrees x s(-1), 300 degrees x s(-1), and 60 degrees x 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 T(300eccH15) (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 soccer-specific conditioning is warranted to try to reduce the incidence or recurrence of hamstrings strains.