Cross-education of unilateral resistance training as a strategy to mitigate immobilisation-induced neuromuscular decline: A systematic review and meta-analysis

Limb immobilisation leads to a rapid and pronounced loss of muscle strength and size. Cross-education – contralateral resistance training of the non-immobilised limb - has emerged as a resistance training strategy to mitigate deficit in the immobilisation limb. A systematic review and three-level hierarchical meta-analysis were conducted (Eight studies were included; n = 189) to quantify the effects of cross-education on strength and muscle mass during unilateral upper limb immobilisation in healthy participants, examining the influence on training modality, muscle specificity and immobilisation model. Standardised mean change effect sizes (SMCR, Hedges’ g) were calculated for strength and muscle size. Cross-education attenuated strength loss compared with immobilisation alone ( g = 0.53, p < 0.001), with effect magnitude moderated by immobilisation location and training modality. Proximal immobilisation yielded greater attenuation (overall: g = 0.62; eccentric: g = 0.82; concentric-eccentric: g = 0.68) than distal immobilisation (overall: g = 0.42; eccentric: g = 0.34; isometric: g = 0.63). Regarding muscle size, cross education produced a small preservation effect in the immobilised limb ( g = 0.19, p = 0.01). This effect was only evident in proximal immobilisation ( g = 0.40) compared to distal ( g = 0.06). Strong positive associations were observed between adaptations in the trained and immobilised limbs for strength ( r = 0.79) and muscle size ( r = 0.81). These findings indicate that cross-education attenuates losses in muscle strength and size during immobilisation. However, these results should be interpreted with caution due to the varying risk of bias among the included studies.