The Effects of Training History and Muscle Fatigue on Load Sharing in a Multiple Muscle System

Abstract

The effects of exercise training history and localized muscle fatigue on the load sharing patterns in a multiple muscle system were investigated. Six male and six female subjects of various training backgrounds performed fatiguing isokinetic knee extension exercises of quick onset and slow onset fatigue. Electromyographic data collected from the 4 superficial quadriceps muscles as well as the hamstring muscles was fed into an EMG-based model of the knee joint. The relative torque contribution of each muscle as predicted by the model was uniquely different for each of the 5 quadricep muscles modeled. The load sharing patterns were effected by the training group among other factors but they were not significantly effected by the interaction of training group and the onset of fatigue.