Contralateral strength training attenuates muscle performance loss following anterior cruciate ligament (ACL) reconstruction: a randomised-controlled trial

Abstract

Purpose: To investigate the effects of cross-education (CE) exercise on strength and performance at 10 and 24-weeks post anterior cruciate ligament (ACL) surgery. Methods: Design: Randomised controlled trial. N=44 ACL-reconstruction patients, randomly-allocated into: CE: strength training of the non-operative limb, or CON: shamexercise of upper limb stretching. Each patient underwent standardised ACL rehabilitation, plus 8 weeks of thrice weekly CE or CON, commencing at 2-weeks postsurgery. The primary outcome was quadriceps peak force (QPF) of the ACL-reconstructed limb at 10-weeks post-surgery. Secondary measures were hamstrings peak force (HPF), rate of force development (RFD) and International Knee Documentation Committee score (IKDC) at 10-and 24-weeks; QPF and hop for distance (HOP) at 24-weeks post-surgeryResults: CE significantly attenuated the decline in QPF of the ACL-reconstructed limb at 10-weeks compared to CON (16.6% decrease vs. 32.0%, respectively); that advantage was not retained at 24-weeks. A training effect was observed in the trained limb for HPF and QPF, which was retained at 24-weeks. No significant differences were observed for IKDC, HOP, RFD, or HPF of the reconstructed limb. Inter-limb symmetry (ILS) ranged from 0.78-0.89 and were not significantly different between groups. Conclusion:High-intensity CE strength training attenuated the post-operative decline in QPF and should be considered in early phase ACL rehabilitation. ILS data showed good symmetry, but it masked significantly inferior performance between groups and should be used with caution.

Exercise prescription and strategies to promote the cross-education of strength: a scoping review

“…There are very little data from randomized clinical trials that have employed a cross-education intervention in patients. Of those that have, there is evidence 45,56,60 showing All rights reserved. No reuse allowed without permission.…”

“…This adaptation has little relevance for individuals with well-functioning limbs. However, in a scenario where one limb is debilitated, unilateral training is a viable intervention to preserve neuromuscular function following orthopedic injury 31,45,56 or neurotrauma. 17,51 Despite evidence showing the therapeutic efficacy of cross-education, unilateral training is still poorly prescribed.…”

“…There are very little data from randomized clinical trials that have employed a cross-education intervention in patients. Of those that have, there is evidence 45,56,60 showing cross-education provides superior adaptations compared to standard care, whereas others 83,84 show similar outcomes with or without unilateral training. Differences in exercise design and prescription likely account for some of the disparity in these clinical trials.…”

“…Differences in exercise design and prescription likely account for some of the disparity in these clinical trials. 56,60,83,84…”

“…Differences in exercise design and prescription likely account for some of the disparity in these clinical trials. 56,60,83,84 The transfer of strength to the opposite, untrained limb is mediated by neural adaptations. With that, exercise interventions that facilitate neural drive of descending motor commands may serve as promising strategies for enhancing the effect.…”