Recovery of Hip and Back Muscle Fatigue Following a Back Extension Endurance Test.

Literature has not shown the minimum time required to recover from muscle fatigue after a prolonged trunk isometric contraction. The purpose of this study was to determine if the lumbar multifidus (LM) and gluteus maximus (GM) muscles would recover from fatigue after three different rest periods following performance of a back extension endurance test. Endurance time and electromyographic (EMG) activity of bilateral LM and GM muscles were collected from 12 healthy adults during a modified Biering-Sørensen test. On three separate visits, each participant performed two modified Biering-Sørensen tests, one before and one after a rest period (3, 6 or 9 min). For each endurance test, endurance time was measured and both mean and median EMG frequency fatigue rates were calculated. The results showed a significantly reduced endurance time and normalized mean frequency fatigue rates on the second modified Biering-Sørensen endurance test regardless of the rest periods (3, 6, and 9 min). This suggests that adequate rest should be considered for fatigue recovery when designing a back and hip endurance exercise program, and that future studies should investigate a rest time longer than 9 minutes for fatigue recovery following a modified Biering-Sørensen endurance test.