Effect of blood flow restriction training according to pressure level on lower extremity muscle activity in adult males

Low-intensity blood flow restriction training is comparable to traditional high-intensity resistance exercises in increasing muscle strength and size. However, determining the optimal level of restriction pressure for blood flow restriction training has remained a challenging issue. In this study, we enlisted 32 healthy adult men and conducted repeated measurements at one-week intervals to explore this issue. Prior to the experiment, we accurately measured the arterial occlusion pressure (AOP) of participants" lower limbs using a color vascular Doppler ultrasound device. Surface electromyography was then utilized to monitor the impact of blood flow restriction squat training at varying relative restriction pressures (0%, 60%, 70%, 80% AOP) on the muscle activity (RMSMVC%) in lower limb muscles(RF, VMO, VLO, BF, SM, GM). The results showed significant variations in the activity of major lower limb muscles at different levels of restriction pressure (p<.05). Notably, blood flow restriction training at 60% to 80% AOP resulted in significantly greater muscle activation than low-intensity exercise without blood flow restriction (p<.05), indicating that low-intensity squat training with blood flow restriction enhances thigh muscle activation. Additionally, the study found that thigh muscle activity at restriction pressures above 70% AOP was significantly greater compared to 60% AOP (p<.05). However, there was no significant difference in thigh muscle activation between the 70% and 80% AOP levels (p>.05). This suggests that restriction pressures above 70% AOP are most effective in activating thigh muscles, but increasing the pressure beyond 70% AOP does not yield additional significant benefits. Therefore, setting the restriction pressure to 70% AOP during lower limb blood flow restriction training is optimal for maximizing fast-twitch muscle fiber recruitment and enhancing muscle adaptation.