The effect of contralateral submaximal contraction on the development of biceps brachii muscle fatigue.

Zwambag, Derek P; Brown, Stephen H M

OBJECTIVE The aim of this study was to determine if a submaximal contraction in the contralateral limb affected the fatigability of the dominant limb. BACKGROUND Muscle fatigue is a known risk factor for musculoskeletal injury; however, it is unknown whether a submaximal contraction in the nondominant limb, such as for stabilizing a tool or load, affects the rate of development of fatigue, potentially increasing risk of injury. Current ergonomic assessments of injury risk do not involve consideration of submaximal contralateral demands. It was hypothesized that increased neuromuscular drive and active muscle mass during bilateral contractions would increase fatigability. METHOD Twelve males isometrically maintained a 30% unilateral contraction and a 30% dominant + 15% nondominant bilateral contraction until failure on two different collection days, separated by 7 days. RESULTS No statistically significant differences were found for time to task failure (p = .6204), decrease in maximal force (p = .1698), or alterations in electromyography amplitude (p = .7223) or frequency (p = .3292) between unilateral and bilateral conditions. CONCLUSION The hypothesis that the addition of a lesser submaximal isometric contraction would increase fatigability was rejected. APPLICATION These findings indicate that in ergonomic settings, muscle fatigability can be estimated by the more demanding task and do not need to be complicated by lesser submaximal contractions in the opposing limb.