Effect of short-term fatigue, induced by high-intensity exercise, on the profile of the ground reaction force during single-leg anterior drop-jumps.

[Purpose] Fatigue may be an important contributing factor to non-contact anterior cruciate ligament injuries in sports. The purpose of this study was to evaluate the effects of controlled lower limb fatigue, induced by a short-term, high-intensity exercise protocol, on the profile of the ground reaction force during landings from single-leg anterior drop-jumps. [Subjects and Methods] Twelve healthy males, 18 to 24 years old, performed single-leg anterior drop-jumps, from a 20 cm height, under two conditions, 'fatigue' and 'non-fatigue'. Short-term fatigue was induced by high-intensity interval cycling on an ergometer. Effects of fatigue on peak vertical ground reaction force, time-to-peak of the vertical ground reaction force, and loading rate were evaluated by paired t-test. [Results] Fatigue shortened the time-to-peak duration of the vertical ground reaction force by 10% (non-fatigue, 44.0 ± 16.8 ms; fatigue, 39.6 ± 15.8 ms). Fatigue also yielded a 3.6% lowering in peak vertical ground reaction force and 9.4% increase in loading rate, although these effects were not significant. [Conclusion] The effects of fatigue in reducing time-to-peak of the vertical ground reaction force during single-leg anterior drop-jumps may increase the risk for non-contact anterior cruciate ligament injury in males.