Abstract: BACKGROUND: Microcirculation, as the only place for the energy metabolism of body substances, is closely related to the human movement ability. Resistance exercise is an effective way to improve the function of microcirculation, but some studies have also pointed out that blood flow restriction exercise can also improve the function of microcirculation and has the advantages of small load and high safety.
OBJECTIVE: To compare the effects of 6-week low-load blood flow restriction exercise and high-intensity resistance exercise on the thigh microcirculation function of athletic young men, and to explore the possible mechanism by which exercises improve microcirculation function from the perspective of vascular endothelial function.
METHODS: Sixty sports students from Hubei Minzu University were divided into control group, high-intensity resistance exercise group and low-load blood flow restriction exercise group according to the random number table method, with 20 students in each group. The low-load blood flow restriction exercise group performed a low-load blood flow restriction exercise for 6 weeks (three times a week, 90 minutes each, at an exercise intensity of 30% 1RM). The high-intensity resistance exercise group received a high-intensity resistance exercise for 6 weeks (three times a week, 90 minutes each, at an exercise intensity of 70% 1RM). The control group did not perform any form of exercise training during this period. Microcirculatory blood perfusion, transcutaneous partial pressure, muscle oxygen saturation, nitric oxide, endothelial nitric oxide synthase, endothelin 1, vascular endothelial cell growth factor, thigh circumference, and muscle strength were tested in each group on the day before the intervention and the morning after the end of the 6-week intervention.
RESULTS AND CONCLUSION: After the exercise intervention, heating values of microcirculatory blood flow perfusion and blood cell movement speed in the low-load blood flow restriction exercise group and the high-intensity resistance exercise group were significantly different from those in the control group and before the exercise intervention (P < 0.05). The heating values of microcirculatory blood flow perfusion and blood cell movement speed showed significant differences between the low-load blood flow restriction exercise group and the high-intensity resistance exercise group (P < 0.05). After the exercise intervention, the levels of nitric oxide, endothelial nitric oxide synthase, endothelin 1, and vascular endothelial cell growth factor were significantly different in the low-load blood flow-limiting exercise group and the high-intensity resistance exercise group compared with the control group and the pre-exercise intervention (P < 0.05). After the exercise intervention, thigh circumference and thigh muscle strength were significantly different in low-load blood flow restriction group and high-intensity resistance exercise groups compared with the pre-exercise intervention (P < 0.05). All these findings indicate that 6-week low-load blood flow restriction exercise and high intensity resistance exercise may regulate the secretion of vascular factors such as endogenous nitric oxide synthase, endothelin-1 and vascular endothelial growth factor to improve the function of thigh microcirculation and increase the contractile strength of the thigh muscle. In addition, And low-load blood flow restriction exercise has better intervention effects on microcirculatory blood perfusion volume and blood cell movement speed, so low-load blood flow restriction exercise is more advantageous than high-intensity resistance exercise in improving microcirculation function.

Key words:  low-load blood flow restriction, high-intensity resistance, microcirculation function, muscle strength, microcirculatory blood flow perfusion, percutaneous oxygen partial pressure, muscle oxygen saturation, nitric oxide, endothelin 1, vascular endothelial growth factor