WEIGHT TRAINING OF THE THIGH MUSCLES USING CLOSED VS. OPEN KINETIC CHAIN EXERCISES - A COMPARISON OF PERFORMANCE ENHANCEMENT

Resistance training is commonly used in sports for prevention oi injur ies and in rehabilitation. The purpose of this study was to compare cl osed vs. open kinetic chain weight training oi the thigh muscles and t o determine which mode resulted in the greatest performance enhancemen t. Twenty-four healthy subjects were randomized into a barbell squat o r a knee extension and hip adduction variable resistance weight machin e group and performed maximal, progressive weight training twice a wee k for 6 weeks. All subjects were tested prior to training and at the c ompletion of the training period. A barbell squat 3-repetition maximum , an isokinetic knee extension 1-repetition maximum, and a vertical ju mp test were used to monitor effects of training. Significant improvem ents were seen in both groups in the barbell squat 3-repetition maximu m test. The closed kinetic chain group improved 23 kg (31%), which was significantly more than the 12 kg (13%) seen in the open kinetic chai n group. In the vertical jump test, the closed kinetic chain group imp roved significantly 5 cm (10%), while no significant changes were seen in the open kinetic chain group. A large increase of training load wa s observed in both subject groups; however, improvements in isotonic s trength did not transfer to the isokinetic knee extension test. The re sults may be explained by neural adaptation, weight training mode, and specificity of tests.