LoRusso, S., Pollock, J., & Gdula, S. (June 03, 2010). Unilateral strength training prevents strength loss in the contralateral limb following bilateral training. Presentation 2091 at the 2010 Annual Meeting of the American College of Sports Medicine, Baltimore, Maryland; June 2-5.

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This study evaluated if four weeks of unilateral strength training could prevent strength loss in the detrained, contralateral limb following four weeks of bilateral training. Ss (M = 13; F = 9) were randomly assigned into a bilateral detraining or a unilateral training group. Following initial baseline bilateral and unilateral 1 RM assessments, Ss underwent four weeks of bilateral leg extension training. Then, some Ss (N = 11) underwent four weeks of bilateral detraining (no training on either leg), while the other half underwent unilateral leg extension training of the right limb with no training of the left limb. Bilateral and unilateral 1 RM measures were taken following four weeks of bilateral training and at the conclusion of the four weeks of detraining or unilateral training.

There were no differences in initial bilateral or unilateral 1 RM strength between groups. Following four weeks of training, bilateral 1 RM increased 43% for both groups, whereas unilateral strength increased non-significantly by an average of 27%. After four weeks of detraining, the bilateral detraining group 1 RM decreased 15.18% and 14.24% in the right and left legs, respectively, while the unilateral training group increased 14.29% in the trained, right leg and 0.48% in the detrained, contralateral left leg. None of these changes were significant. However, in terms of percent change between the bilateral detraining left limb and the unilateral training left limb Mann-Whitney analysis indicated a significant difference following the detraining period, where the unilateral training group had a near 0% change in strength versus the bilateral detraining left limb that lost 14.24%. Also, the difference between the increased strength in the unilateral training right limb versus the near zero change in unilateral training left was significant.

Implication. In already trained individuals, unilateral strength training on a good limb may prevent strength loss in a non-training contralateral limb. This has direct implications for what type of rehabilitative work can be performed when recovering from injury.

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