The effect of blood flow restriction resistance exercise on arm muscle strength and isokinetic contraction parameters

While high-load resistance training (HL-RT) is well established as an effective method for improving muscle strength, low-load blood flow restriction training (LL-BFRT) has been suggested to induce similar neuromuscular adaptations while imposing substantially lower mechanical stress. However, direct comparative evidence between LL-BFRT and HL-RT in the upper limbs remains limited. Twenty-two healthy male participants (age: 26.3 ± 7.2 years, range:18–40, height: 176.9 ± 6.5 cm; body mass: 77.9 ± 13.5 kg) were randomly allocated to either LL-BFRT (n = 12) or HL-RT (n = 10). The LL-BFRT group trained at 30% of 1RM (4 sets; 30-15-15-15 repetitions) with progressive arterial occlusion pressure (30–50%), while the HL-RT group trained at 70% of 1RM (3 sets; 10–12 repetitions). Both groups, within their redesigned and equalised training programs, performed biceps curls and triceps pushdowns twice weekly for 7 weeks. Isokinetic muscle strength outcomes, including peak torque, relative strength, and total work, were assessed using isokinetic dynamometry (Isomed 2000, 60°/s). Maximal muscle strength outcomes included one-repetition maximum (1RM) strength. Statistical analyses were performed using two-way repeated measures ANOVA with Bonferroni corrections, reporting effect sizes (η²) and 95% confidence intervals (CI). Both groups demonstrated significant pre- and post-improvements in isokinetic strength parameters (p < 0.05). No significant group × time interaction was observed for peak torque (right arm extension: LL-BFRT + 4%, HL-RT + 9%; p = 0.478, η²=0.049). Both groups showed within-group increases in total work (LL-BFRT right arm + 16.3%, HL-RT + 8.4%) and relative strength (LL-BFRT left arm flexion + 19.0%, HL-RT + 10.6%). No adverse events were reported. Preliminary evidence suggests that LL-BFRT can induce meaningful strength gains in healthy adults. These findings support LL-BFRT as a safe and potentially effective training alternative when high loads are not feasible, particularly in rehabilitation contexts. However, the small sample size and short duration of the study limit the generalizability of the results. Future studies with larger samples and extended follow-up periods are needed to confirm and expand upon these findings. These findings should be interpreted cautiously due to the limited statistical power to detect small-to-moderate between-group differences. ClinicalTrials.gov, NCT07462520. Registered 5 March 2026.