Effect of Low-Intensity Bloodflow Restriction Training on Nontraumatic Knee Joint Conditions: A Systematic Review and Meta-analysis.

Context: Nontraumatic knee conditions are common in clinical practice. Existing pharmaceutical and immobilization approaches provide limited pain relief and functional enhancement. Low-intensity bloodflow restriction training (LI-BFRT) is being investigated as a nonpharmacological alternative; however, its efficacy is uncertain.

Objective: To assess the effectiveness of LI-BFRT for nontraumatic knee conditions and compare it with high-intensity resistance training (HI-RT) and low-intensity resistance training (LI-RT).

Data Sources: PubMed, EBSCO, Science Direct, Cochrane Library, China Knowledge Infrastructure, Wanfang Data, and VIP databases were searched until May 30, 2023.

Study Selection: Original randomized controlled trials involving nontraumatic knee joint conditions with interventions consisting mainly of LI-BFRT, HI-RT, or LI-RT. The results assessed mainly pain and muscle performance.

Study Design: Systematic review and meta-analysis.

Level Of Evidence: Level 1.

Data Extraction: Sample characteristics, study design, country, disease, groups, evaluation time, duration, and outcomes were extracted.

Results: A total of 13 randomized controlled trials were included in the systematic review. Compared with pretreatment, LI-BFRT significantly alleviated pain (weighted standardized mean difference [SMD], -1.33; 95% CI, -1.62 to -1.05), with better additional effects on hip muscle training (SMD, -3.14; 95% CI, -4.07 to -2.75). Compared with LI-RT, LI-BFRT significantly relieved pain in male patients (SMD, -1.47; 95% CI, -1.92 to -1.01). LI-BFRT significantly increased quadriceps cross-sectional area (SMD, 0.53; 95% CI, 0.27-0.78), knee extension strength (SMD, 0.84; 95% CI, 0.48-1.2), and leg press strength (SMD, 0.64; 95% CI, 0.34-0.94) compared with pretreatment. Its effects were superior to those of LI-RT and similar to those of HI-RT. However, sex differences in muscle strength improvement were observed.

Conclusion: In patients with nontraumatic knee joint conditions, LI-BFRT effectively alleviated pain, increased muscle cross-sectional area, and enhanced muscle strength. LI-BFRT showed pain relief comparable with that of LI-RT while surpassing LI-RT in muscle growth and strength improvement.