Abstract: OBJECTIVE: To systematically evaluate the effects of low-load blood flow restriction training and walking training with blood flow restriction on muscle strength, muscle mass and physical performance in older adults, thereby providing a theoretical basis for the scientific application of blood flow restriction to the prevention and treatment of senile sarcopenia. 
METHODS: A computer-based search was conducted in PubMed, Embase, Cochrane Library, CNKI, WanFang, VIP, and CBM. Randomized controlled trials regarding the effects of blood flow restriction training on muscle mass, muscle strength and physical performance in older adults were included from inception to August, 2021. The literature quality was assessed using the bias assessment tool recommended by the Cochrane Collaboration by at least two evaluators and RevMan5.4 software was used to conduct meta-analysis of relevant data. Evaluation indicators contained three continuous variables including muscle strength, muscle mass and physical performance. Subgroup analysis was carried out for different test methods of outcome indicators included in the literature 
RESULTS: A total of 16 randomized controlled trials, including 348 patients in total, were included according to the inclusion criteria. The quality of the literature was graded according to the Cochrane Collaboration’s risk of bias assessment tool, including 11 studies of grade B and 5 of grade C. The results of Meta-analysis showed that compared with high-load resistance training, low-load blood flow restriction training could improve muscle strength [standardized mean difference (SMD)=-0.14, 95% confidence interval (CI):-0.34-0.06, P=0.17] and muscle mass (SMD=0.08, 95% CI: -0.23-0.40, P=0.60) in older adults; compared with low-load resistance training, low-load blood flow restriction training and walking training with blood flow restriction could significantly improve muscle strength (SMD=0.57, 95% CI: 0.28-0.87, P=0.000 2); compared with walking training, walking blood flow restriction training significantly could improve muscle strength (SMD=0.62, 95% CI: 0.32-0.91, P < 0.000 1], but there was no significant change in muscle mass (SMD=0.28, 95% CI: -0.01-0.57, P=0.06) and physical performance (SMD=0.61, 95% CI: -0.04-1.26, P=0.07). The results of subgroup analysis showed that heterogeneity was reduced. The muscle strength via low-load blood flow restriction training and walking training with blood flow restriction was significantly better than that via low-load training by means of maximum voluntary contraction (SMD=0.95, 95% CI: 0.25-1.65, P=0.008) and isokinetic torque testing (SMD=0.80, 95% CI: 0.16-1.45, P=0.01], and the physical performance via walking training with blood flow restriction was significantly better than that via walking training by means of physical function evaluation (SMD=0.94, 95% CI: 0.35-1.52, P=0.002).
CONCLUSION: Meta-analysis results of the existing 16 randomized controlled trials indicate that compared with the traditional resistance training and walking training, low-load blood flow restriction training and walking training with blood flow restriction can also increase muscle strength and muscle mass in older adults. Although the large-scale randomized controlled trials are still needed on the improvement of physical performance, low-load blood flow restriction training and walking training with blood flow restriction could be good ways to prevent elder population from sarcopenia. 

Key words: older adults, blood flow restriction training, resistance training, walking, muscle strength, muscle mass, physical performance, Meta-analysis