Effects of cast-bracing of the knee on physical performance in healthy subjects

Effects of application of a hinged cast-brace on thigh muscle strength and physical performance tests were studied in eight healthy volunteers. The cast-brace was applied to one leg for four weeks. The subjects were free to move around. The extra loading by the cast-brace was determined in a progressive uphill walk test on a treadmill with measurements of oxygen uptake, heart rate and plasma lactate concentration. Submaximal oxygen uptake in the uphill walk test was raised significantly (average 9%) on the day after application. After four weeks of cast-brace wearing the submaximal oxygen uptake in the uphill walk test had decreased, but remained elevated (average 4%) even one day after removal. Heart rate was significantly higher (average 7%) during cast application and after removal. Plasma lactate concentration, however, was not influenced. To investigate the effect of four weeks cast-bracing various performance tests to judge the thigh muscle function were taken before application and after removal. No significant changes in peak torque of knee flexion and extension, in physiologic variables at submaximal running pace during treadmill exercise, maximal running speed, 60 m dash, or in jump height were found. In conclusion, cast-bracing of a healthy knee for four weeks has no significant effects on physical performance after removal.