Background: Return to activity decisions after anterior cruciate ligament reconstruction (ACL-R) are limited by functional performance tests often performed in a non-fatigued state. Fatigue can improve test sensitivity, but current methods to induce fatigue are typically bilateral tasks or focus on the quadriceps muscle in isolation.Hypothesis/Purpose: To determine the effects of a two-minute lateral step-down fatigue test compared to a 30-second side-hop test on single-leg forward hop distance in healthy individuals. It was hypothesized that participants would demonstrate decreased hop distance with both tests, but the two-minute lateral step-down fatigue test would result in greater deficits in single-leg forward hop distance. Study Design: Randomized crossoverMethods: Twenty healthy participants (16 females, 4 males; age=23.7±3.0 years, height=153.8±36.2 cm; mass=64.4±12.8 kg; Tegner=6.8±1.2) were asked to perform single-leg forward hop for distance pre-and postfatigue. Participants were randomly assigned to one of the two fatigue tests, 30-second side-hop or 2-minute lateral step-down test, during the first visit. They returned within a week and performed the same sequence of tests but underwent whichever fatigue test was not assigned at the prior visit.Results: There was a significant decrease (p < 0.001) in single-leg forward hop distance following the 30-second sidehop test (pre=134.1±23.7 cm, post=126.2±24.4 cm) and the two-minute lateral step-down test (pre=135.0±26.1 cm, post=122.7±27.4 cm). The decrease in hop distance was significantly greater (p < 0.001) for the two-minute lateral step-down test compared to the 30-second side-hop test. Conclusion:The two-minute lateral step-down test resulted in a greater decrease in hop performance compared to the 30-second side-hop test. The results establish a thresh old for expected changes that occur in a healthy population and that can then be compared with an injured athlete population. The two-minute lateral step-down exercise may be an effective method of inducing fatigue to better mimic performance in a sports environment to inform return-tosport decisions.