Cross‐education attenuates muscle weakness and facilitates strength recovery after orthopedic immobilization in females: A pilot study

This pilot study consists of a two‐phase intervention to examine the effectiveness of unilateral resistance training to mitigate the negative consequences of immobilization and expedite the restoration of muscle strength and size following a period of retraining. Ten females were randomized to a unilateral training (TRAIN, n = 6) or control (CON, n = 4) group. During Phase 1, all participants wore an arm sling for a total of 4 weeks on their non‐dominant arm. This phase required the TRAIN group to perform unilateral resistance training with the non‐immobilized arm while the CON group did not. Phase 2 commenced thereafter and consisted of 4 weeks of bilateral resistance training for both groups. Outcome measures of neuromuscular function and muscle size were assessed at baseline and after each phase, with neuromuscular function quantified by maximal dynamic and isometric strength alongside electromyographic responses and muscle size measured using ultrasonography and regional lean mass via DEXA. Unilateral training of the non‐immobilized arm during Phase 1 attenuated dynamic (p < 0.05; g > 1.2), but not isometric (p > 0.40; g < 0.095), strength loss following immobilization and showed large effects for improving the recovery of strength after retraining. Similarly, the imaging data show the relative changes in muscle size and regional lean mass of the non‐dominant arm favor TRAIN. Although the small sample prevents definitive conclusions, our study suggests resistance training of the non‐immobilized arm attenuates muscle weakness and atrophy for the contralateral, immobilized arm during immobilization and facilitates their recovery following retraining.