EFFECT OF A LATERAL STEP-UP EXERCISE PROTOCOL ON QUADRICEPS AND LOWER-EXTREMITY PERFORMANCE

Closed kinetic chain exercises have been promoted as more functional a nd more appropriate than open kinetic chain exercises. Limited researc h exists demonstrating the effect of closed kinetic chain exercise on quadriceps and lower extremity performance. The purpose of this study was to determine the effect of a lateral step-up exercise protocol on isokinetic quadriceps peak torque and the following lower extremity ac tivities: 1) leg press, 2) maximal step-up repetitions with body weigh t plus 25%, 3) hop for distance, and 4) 6-m timed hop. Twenty subjects participated in a 4-week training period, and 18 subjects served as c ontrols. For the experimental group, a repeated measure ANOVA comparin g pretest and posttest values revealed significant improvements in the leg press (p less-than-or-equal-to .05), step-ups (p less-than-or-equ al-to .05), hop for distance (p less-than-or-equal-to 05), and hop for time (p less-than-or-equal-to .05) and no significant increase in iso kinetic quadriceps peak torque (p greater-than-or-equal-to .05). Over the course of the training period, weight used for the step-up exercis e increased (p less-than-or-equal-to .05), repetitions decreased (p le ss-than-or-equal-to .05), and step-up work did not change (p greater-t han-or-equal-to .05). For the control group, no significant change (p greater-than-or-equal-to .05) occurred in any variable. The inability of the isokinetic dynamometer to detect increases in quadriceps perfor mance is important because the isokinetic values are frequently used a s criteria for return to functional activities. We conclude that close d kinetic chain testing and exercise provide additional means to asses s and rehabilitate the lower extremity.