Injuries often leave one limb immobilized, driving a rapid decline in muscle strength and size. But what if training the opposite limb could help preserve the strength of the immobilized one? A recent study found that targeted exercise of one arm can help maintain strength and size in the opposite immobilized arm, offering potential benefits for rehabilitation.

Researchers immobilized the nondominant forearms of 16 adult participants for four weeks using a cast. Then, they randomly assigned them to a resistance training or non-exercising group. Participants in the training group performed eccentric wrist flexion exercises with the non-immobilized arm three times a week. Both groups underwent testing before and after the intervention to measure muscle strength, thickness, and cross-sectional area using ultrasound and computed tomography.

The researchers found that those in the training group experienced only a 2.4% reduction in strength in the immobilized arm compared to a 21.6% reduction in the non-training group. In addition, the training group saw a 1.3% increase in muscle size of the immobilized forearm, while the non-training group showed a 2.3% decrease. They also observed strength gains in the non-immobilized arm, with a 30.8% improvement in the training group compared to a 7.4% decline in the non-training group.

These findings suggest that engaging in targeted resistance training of the non-immobilized limb can help preserve the size of an immobilized limb and maintain strength across different types of muscle contractions. The researchers posited that the immobilized arm retained more muscle mass and strength due to neural adaptations from training the opposite arm, a phenomenon known as cross-education effects. Interestingly, sauna use can also help maintain muscle mass during periods of disuse due to immobilization. Learn more in our overview article.