Effects of various isoresistive training programmes on trunk muscle performance

Isoresistive movements provide a functional method of testing muscle performance and of providing exercise; the resistance applied is usually a percentage of the maximal isometric torque which can be developed by individual subjects. The aim of the current study was to compare the effectiveness of dynamic isoresistive exercise programmes using 25, 50 or 75% of the maximum isometric flexion torque and static isometric exercises for improving the performance of the trunk flexors and extensors. Subjects comprised 42 asymptomatic females aged 18–25 years who were randomly assigned to control or exercise groups. The exercise groups undertook 2 min of exercise 3 times per week. The control subjects showed significant improvement between tests indicating a strong learning effect. The study showed that the subjects who exercised at 50% of maximum flexion isometric torque achieved the greatest increases in muscle performance on most measures. Maximal isometric flexion and extension torques did not significantly change in any of the groups. Flexion and extension velocity and power were the muscle performance characteristics which improved the most in response to the training programmes.