Low-Load Resistance Exercise With Blood Flow Restriction Versus High-Load Resistance Exercise on Hamstring Muscle Adaptations in Recreationally Trained Men

Abstract Kamiş, O, Gürses, VV, Şendur, HN, Altunsoy, M, Pekel, HA, Yıldırım, E, and Aydos, L. Low-load resistance exercise with blood flow restriction vs. high-load resistance exercise on hamstring muscle adaptations in recreationally trained men. J Strength Cond Res XX(X): 000–000, 2024—Low-load resistance exercise with blood flow restriction (BFR-RE) has been suggested as a viable alternative exercise for traditional high-load resistance exercise (HL-RE). However, very little is known about hamstring muscle thickness, stiffness, and strength after BFR-RE. This study aimed to compare the effects of 6 weeks of BFR-RE and HL-RE on hamstring muscle thickness, stiffness, and strength. Twenty-nine recreationally trained men were pair matched and randomly assigned to the BFR-RE ( n = 15) and HL-RE ( n = 14) groups. The BFR-RE groups performed bilateral lying leg curl exercise (30-15-15-15 reps, 30-second rest between the sets, 30% 1RM) with BFR cuffs (60% of limb occlusion pressure), whereas HL-RE performed the same exercise (3 × 12 reps, 90-second rest between the sets, 70% 1RM) without BFR cuffs. Hamstring muscle thickness, muscle stiffness, isokinetic muscle strength, and 1RM were assessed at baseline and follow-up after completing a 6-week resistance exercise program (3× a week). Hamstring muscle thickness was assessed by ultrasonography, whereas muscle stiffness was evaluated by shear wave elastography. Isokinetic dynamometry and a 1RM strength test were used to determine muscular strength before and after the exercise program. Statistical significance was set at p < 0.05. No significant effect was found for hamstring muscle strength, thickness, and stiffness for group and group × time interaction, and only a significant main effect of time ( p < 0.001) was observed for all outcomes. Both groups experienced significant improvements for all outcomes from baseline to follow-up without any between-group differences. In conclusion, results revealed that BFR-RE can provide similar hamstring muscle strength, thickness, and stiffness compared with HL-RE.