Number of repetitions to maximum in hop tests in patients with anterior cruciate ligament injury.

The unilateral horizontal, triple cross-over and vertical hops are commonly used as outcome measures after knee injury but there is little knowledge of the number of repetitions needed to reach maximum performance. Seventy subjects who had either an anterior cruciate ligament deficient or reconstructed knee participated in this study. Unilateral vertical, horizontal, and triple cross-over hop testing was applied to each leg until two consecutive decrements in performance occurred. The number of repetitions to reach maximum during these tests were calculated. Fifteen repetitions of the horizontal and vertical hops, and 10 repetitions of the triple-crossover hop enable distances to be achieved that are acceptably close to maximal levels in these knee-injured patients. In order to increase the likelihood of finding a patient's maximum hop performance after knee injury, more repetitions are suggested than has been reported in the literature.