The Benefit of a Single-Leg Strength Training Program for the Muscles around the Untrained Ankle: A Prospective, Randomized, Controlled Study

Severe ankle injuries can require extended periods of immobilization that adversely affect the strength of the ankle muscles. We have investigated a single-leg strength training program of the muscles surrounding the ankle to determine if it produces a crossover benefit for the contralateral ankle muscles. Twenty subjects without any history of ankle injuries were randomly divided into a control and a training group. Both groups underwent isokinetic testing of the ankle muscles at the beginning and end of an 8-week period. The control group maintained normal activities between the tests. Half of the training group trained the dominant leg only and the other half trained the nondominant leg only for the 8-week period, three times per week. The subjects who trained the dominant leg improved peak torque values by 8.5% in the trained leg and 1.5% in the untrained leg. Similarly, the subjects who trained the nondominant leg improved peak torque values by 9.3% in the trained leg and 3.5% in the untrained leg. In contrast, the control group showed no significant change in peak torque, power, or endurance between the initial and final tests. With improvements in peak torque as high as 40% in the trained leg and a crossover benefit of 19% in the untrained leg in eccentric inversion, this strength training technique deserves further investigation in an injured population where the benefits may be more substantial.