Cross-Education Effect on Force Production Capacity After Unilateral Resistance Training in Clinical Populations: A Systematic Review with Meta-analysis.

In 30 seconds

This systematic review and meta-analysis examined unilateral resistance training and force gains in the opposite, untrained limb among healthy immobilised participants and people with musculoskeletal conditions or post-stroke hemiparesis. Across 24 controlled studies, training produced a moderate improvement in maximal strength versus control (standardised mean difference 0.654 [95% CI 0.393, 0.915], P < 0.001) and a small improvement in rapid force production. Effects were evident in immobilisation models and post-stroke hemiparesis, but not statistically significant in musculoskeletal conditions. Evidence certainty varied by outcome and subgroup.

Key findings

• Maximal strength improved moderately versus control: ES 0.654 [95% CI 0.393, 0.915], P < 0.001; certainty was moderate.
• Rapid force production showed a small effect: ES 0.367 [95% CI 0.115, 0.619], P = 0.007; certainty was low.
• Effects were large in post-stroke hemiparesis (ES 1.263 [0.439, 2.087]) and healthy immobilisation models (ES 0.845 [0.533, 1.158]).
• No significant effect was observed in musculoskeletal conditions (P = 0.150), concentric protocols (P = 0.411), or lower-limb protocols (P = 0.093).

Why it matters

Unilateral training may help preserve or improve force production in an untrained limb when direct training is constrained, including during immobilisation and after stroke. The findings also suggest that effects differ across populations and training approaches, so pooled benefits should not be assumed to apply uniformly. The evidence is less supportive for musculoskeletal conditions, where further study is needed.

What to keep in mind

Evidence certainty ranged from very low to high across analyses, and substantial heterogeneity was present in several subgroups. The review also identifies a need for further research, particularly in musculoskeletal conditions.