Decrease In Eccentric Hamstring Strength During Simulated Soccer Match-play

Abstract

Epidemiological research into professional soccer reports a propensity for eccentric hamstring strain injury. Furthermore, injury incidence has been observed to increase during the latter stages of match-play, attributed to fatigue. The intermittent activity profile of soccer increases the complexity of the physiological and mechanical stressors imposed on the player, and makes methodological intervention difficult. PURPOSE To develop a treadmill protocol based on the activity profile of professional soccer match-play, and thereby to simulate the physiological and mechanical demands of match-play. Subsequently to investigate the cumulative effect of soccer-specific fatigue on eccentric hamstring strength. METHODS Seven semi-professional soccer players completed the treadmill protocol, which comprised two 45 min exercise periods separated by a 15 min interval to represent half-time. A 15 min activity profile was developed, which was repeated six (6) times in total. The 15 min activity profile comprised 195 discrete bouts of exercise, producing a change in speed every 6s on average. Within this activity profile seven (7) movement speeds were included. Peak eccentric hamstring torque (T) of the dominant leg was obtained at isokinetic testing speeds of 180°s−1 (T180), 300°s−1 (T300) and 60°s−1 (T60). These measures were obtained at rest (00 min.; t00), at the end of the first half (45 min.; t45) and at the end of the second half (105 min.; t105). RESULTS ANOVA identified a significant (P<0.05) main effect for time at the fastest isokinetic trial, with T300 significantly reduced at t105 (145.88 ± 19.97 Nm) compared with t00 (205.0 ± 37.77 Nm). T300 at t45 (176.82 ± 26.12 Nm) was not significantly different to either t00 or t105, suggesting a progressive decrease in eccentric strength during the course of match-play. Whilst there was a trend for progressive reduction in eccentric hamstring strength over the course of the simulated match at testing speeds of 60°s−1 (T60 = 162.22 ± 27.36 Nm at t00; 145.82 ± 23.47 Nm at t45; 129.94 ± 20.81 at t105) and at 180°s−1 (T180 = 181.96 ± 31.86 Nm at t00; 152.60 ± 22.22 Nm at t45; 140.52 ± 18.79 Nm at t105), this decline was not significant. CONCLUSION The intermittent activity profile of soccer match-play was shown to induce a significant deterioration in eccentric hamstring strength at the fastest test speed. This reduction in eccentric strength predisposes the hamstring muscle complex to strain injury, particularly during sprinting activities, and particularly during the latter stages of match-play.