Article Text
Abstract
Background Cross-education occurs when unilateral resistance training results in a strength transfer to the contralateral limb. This study explores the application of cross-education in injury rehabilitation.
Objective This study investigated the effectiveness of unilateral elastic resistance training on shoulder and elbow strength and neuromuscular activation in the contralateral limb. The secondary aim was to identify the impact of training velocity on these adaptations.
Design A within-subject randomised controlled trial.
Setting University students were tested in the lab before and after a home-based training programme.
Patients (or Participants) Twenty-nine healthy, sedentary, young adults (21.2 ± 0.9 years) were match randomised into four intervention groups according to training arm dominance and movement velocity (60°/s vs. 240°/s): fast-dominant, fast-nondominant, slow-dominant and slow-nondominant.
Interventions (or Assessment of Risk Factors) Participants completed a home-based 6-week unilateral strength programme including resistance tubing exercises of shoulder internal/external rotation and elbow flexion/extension.
Main Outcome Measurements Peak torque (PT) and surface electromyography (EMG) was recorded during maximal voluntary isometric contractions (MVIC), isokinetic concentric 60°/s and 240°/s contractions two weeks before intervention, pre-intervention, and post-intervention.
Results All groups had significant PT increases in untrained arm elbow extension at 60°/s and 240°/s (P<0.01). The slow and the dominant arm groups experienced significant PT improvements (P<0.05) in internal rotation at 240°/s.
The trained arm of the slow-dominant group had significant increases in EMG peak amplitude for supraspinatus external rotation 60°/s and triceps elbow extension MVIC (P<0.05), with the untrained arm also increasing significantly in elbow extension MVIC. The dominant groups showed significantly greater peak EMG increases than the non-dominant groups in trained supraspinatus 240°/s and untrained teres major MVIC (P<0.05).
Conclusions Unilateral elastic resistance training produces strength and neuromuscular benefits in both arms, suggesting that home-based interventions are a potential rehabilitation adjunct in preventing reinjuries. Cross-education is greatest when the dominant arm is trained at slower velocities.