Background
Cross-education (CE) involves strength and volume improvements in the untrained contralateral limb after unilateral training, with potential benefits in rehabilitation. Blood flow restriction training (BFR), using low-load exercises, may enhance CE effects, but its efficacy requires systematic evaluation.
Objective
To systematically assess the effects of low-load BFR on the CE of muscle strength and volume, providing evidence-based guidance for clinicians and rehabilitation therapists.
Design
Systematic review and meta-analysis.
Data Sources
PubMed, Web of Science, and Embase databases from inception through March 1, 2024.
Study Selection
Eligible studies investigated adults; included a synchronous training intervention for ≥4 weeks; compared ≥1 unilateral training group or a nonintervention control group; reported outcomes for ≥1 measure of maximal force, voluntary contraction, isometric strength, torque, or muscle cross-sectional area preintervention and postintervention; and had an experimental design.
Data Extraction
Two researchers extracted publication characteristics, participant grouping, participant characteristics, training characteristics, and outcome indicators after the exercise intervention.
Data Synthesis
We calculated standardized mean differences for muscle strength and mean differences for muscle volume, with heterogeneity assessed via the Higgins I
2 test. We used the Cochrane Collaboration’s randomized controlled trial bias evaluation tool for quality assessment.
Results
Of 1729 records retrieved, 6 articles (N = 259 young adults) were included in the meta-analysis. Results indicated a markedly enhanced CE effect in muscle-strength induction via BFR, with a combined effect size (standardized mean difference) of 0.59 (95% CI = 0.24, 0.94; P = .001) compared with the blank control group and 0.29 (95% CI = 0.06, 0.52; P = .01) compared with the unilateral resistance training group. Nonetheless, the CE effect on muscle-volume induction showed no notable variance between the BFR group and the blank control group (mean difference = −0.01; 95% CI = −0.06, 0.04; P = .60) or the unilateral resistance training group (mean difference = 0.01; 95% CI = −0.04, 0.06; P = .64).
Conclusions
Blood flow restriction effectively induced CE in muscle strength. Nevertheless, additional research is required to determine its effect on muscle-volume CE. Reduced exercise intensity with BFR may augment neural activation, implying possible advantages in rehabilitative training for individuals with neurological conditions, meriting additional investigation.