Effects of isokinetic versus isotonic training on strength, power and muscular balance of rotator cuff muscles among advanced level of adolescent weightlifters

Abstract

Weightlifting is a sport that demands dynamic strength and power which involves a multi joint movement and whole body lifts. As an important kinetic chain involved in motions of weightlifting, previous literatures reported shoulder injuries due to muscular imbalance of shoulder rotator cuff muscles. Therefore, the study was conducted to evaluate the effects of isokinetic versus isotonic training on strength, power and muscular balance of the rotator cuff. A total of 24 state-level weightlifters were recruited and randomly assigned (gender- and weight-matched) into either isokinetic or isotonic group. However, only 19 participants successfully completed the intervention programme. Both groups went through 24 sessions of a training program three times per week for eight weeks. The intensity of training was increased progressively in terms of number of repetitions and set. Isokinetic variables of peak torque per body weight, time to peak torque, average power and external to internal rotators muscular strength ratio were recorded before and after the commencement of training and one month following the cessation of training. There was a non-statistically significant trend that indicated positive changes in the biomechanical adaptations of the rotator cuff in the isokinetic group compared to the isotonic group in terms of peak torque/body weight, time to peak torque and average power. In conclusion, both isokinetic and isotonic training specifically for rotator cuff has a potential to be proposed as an additional training among experienced weightlifters to improve their performance.