EFFECT OF CONCENTRIC AND ECCENTRIC ISOTONIC RESISTANCE TRAINING PROGRAMS ON KNEE ANGLE SPECIFIC HAMSTRINGS/QUADRICEPS RATIOS

Abstract

1201 We have previously described a functional model of hamstrings (H) and quadriceps (Q) interaction based on knee angle specific HQ ratios (H/Q). The purpose of this study was to evaluate the effect of standard concentric (CON) and combined concentric/eccentric (ECC) hamstring training protocols on knee angle specific H/Q. Active male volunteers (n=30) were randomly assigned to two groups. The CON group (N = 15) participated in a 16 week progressive resistance hamstring strengthening protocol (hamstring curls) performed on a modified Cybex™ isotonic resistance device. The ECC group (N = 15) performed an identical concentric protocol with an additional progressive overload (60 to 100% of CON 1RM) applied during the eccentric phase of the exercise using a motor driven weight stack (NEGATOR™, Myotonics Corporation, Metairie, LA) attached to the modified Cybex™ platform. Knee angle specific H/Q were computed at knee angles of 20, 30, 40, 50, 60, 70, and 80 degrees of knee flexion for hip angles of 90 and 180 degrees using a Cybex 6000 isokinetic dynamometer at 60 deg/sec. Repeated measures ANOVA revealed a significant (p = 0.002) time (pre/post) effect as well as a significant (p = 0.03) time x knee angle x hip angle x group interaction. Post Hoc analysis revealed significant increases in H/Q for both CON and ECC groups at all knee angles (p<0.001) at the hip angle of 90 degrees. At 180 degrees of hip angle, significant differences in H/Q for both training groups were observed for knee angles of 20, 30, 40, 50, and 60 degrees (p<0.001). The results of this study reveal that the knee angle specific H/Q responds similarly to both eccentric and concentric isotonic hamstring resistance training protocols.