Kamiş, OkanGürses, V. VolkanŞendur, H. NahitAltunsoy, MustafaPekel, H. AhmetYıldırım, Erkan2024-09-032024-09-0320241064-8011https:/dx.doi.org/10.1519/JSC.0000000000004870https://hdl.handle.net/20.500.12451/12402Kamis‚, O, G ¨urses, VV, S‚ endur, 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 5 15) and HL-RE (n 5 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 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 (33 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 3 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 followup 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.eninfo:eu-repo/semantics/embargoedAccessHypertrophyMuscle StiffnessShear Wave ElastographyStrengthVascular OcclusionArticle10.1519/JSC.0000000000004870Q1