A bi-directional bicycle pedal that combines proprioceptive training and evertor strengthening has been developed for the treatment of residual instability after ankle sprains. A prospective randomized study was carried out on 19 subjects with recurrent ankle sprains and positive stress X-ray films. The subjects were randomized to use either a bi-directional test pedal or a traditional uni-directional bicycle pedal and then completed a 6-week high-intensity training program on a cycle ergometer. Assessment of training intensity level was based on maximum oxygen uptake values, heart rate and lactate concentration in blood at various submaximal workloads. After completion of the training program, the subjects who had used the test pedal increased peak eversion torque at 180 degrees degrees s-1 by 14.2% (P = 0.020), reduced figure-of-eight running time by 0.24 s (P = 0.003), improved single leg stance speed from 72.5% to the maximum speed of 80% (P = 0.005), and improved Karlsson functional score by 5.1 points (P = 0.005). In the control group, single leg stance improved from 56.1 to 67.8% (P = 0.018), but otherwise no significant effects were found. This study indicates that short-term high-intensity training with a bi-directional pedal improves ankle performance and may be an option in the treatment of recurrent ankle sprains.