Submaximal low-load resistance exercise with blood flow restriction produces similar results to low-load exercise to failure for muscle size and strength, but not endurance.

Purpose: To examine the effects of submaximal low-load resistance exercise with and without blood flow restriction (BFR) on muscle size, strength, cross-education of strength, and muscular endurance with BFR compared to low-load exercise to failure.

Methods: 144 participants were randomly assigned to: (1) submaximal low-load exercise (LL, n = 37), (2) submaximal low-load exercise with BFR (LL + BFR, n = 35), (3) low-load exercise to failure (LL-Failure, n = 36), and (4) non-exercise control (CON, n = 36). Training consisted of 2 sets of 30% 1RM elbow flexion exercise, performed 3 days/week for 6 weeks. Repetitions performed by the submaximal groups were based on the muscular endurance test with BFR during pre-testing (70% of maximal BFR repetitions in week 1 and 95% in week 6).

Results: LL + BFR led to greater increases in muscle thickness (0.14 cm) compared to LL (0.06 cm), and was comparable to LL-Failure (0.17 cm). 1RM strength gains were greater in LL (0.45 kg), LL + BFR (0.54 kg), and LL-Failure (0.34 kg) compared to CON (-0.36 kg), with no differences between training groups. There was no evidence of cross-education of strength. Changes in muscular endurance with BFR were greatest in LL-Failure (16.5 reps), followed by LL + BFR (10.0 reps), LL (4.2 reps), and CON (-0.03 reps).

Conclusion: The effectiveness of BFR during submaximal exercise may depend on the specific adaptation targeted. Submaximal BFR produced muscle growth comparable to failure training. Neither BFR nor proximity to failure was necessary to maximize strength gains. Muscular endurance with BFR increased in all training groups, but improved the most with failure training.