Effect of four weeks of repeated sprint training with blood flow restriction on upper limb microcirculation in boxers

This study evaluates the impact of 4 weeks of 40% arterial occlusion pressure (AOP) blood flow restriction (BFR) combined with repeated sprint training (RST) on the microcirculation function of upper limbs in boxers and investigates the potential mechanisms underlying improvements in microcirculation from the perspective of blood factor changes. Thirty-six healthy male collegiate boxers were assigned to either a blood flow restriction training group (Experimental Group, EG, n = 18) or a conventional training group (Control Group, CG, n = 18), completing 12 sessions over 4 weeks (three sessions per week). The training regimen for EG and CG was identical, except EG underwent BFR during the training sessions. Measurements of arm circumference, muscle strength, microcirculation function (4 indicators), and blood factor (4 indicators) were taken one day before training began and the day after the final training session. Using two-factor repeated measures ANOVA, significant differences were observed in EG's arm circumference at tension, muscle strength, microvascular blood flow perfusion, transcutaneous oxygen pressure, muscle oxygen saturation, nitric oxide levels, endothelial nitric oxide synthase, endothelin-1, and vascular endothelial growth factor, all showing improvements from baseline. In contrast, CG only demonstrated increased upper limb strength, with no significant changes in the other indicators. These findings suggest that while both training protocols may enhance muscle strength, the addition of BFR notably improves upper limb microcirculation and muscle strength in collegiate boxers by modulating the secretion of blood factors such as endothelial nitric oxide synthase, endothelin-1, and vascular endothelial growth factor.