Muscular adaptations to fatiguing exercise with and without blood flow restriction.

The purpose of this study was to determine the muscular adaptations to low-load resistance training performed to fatigue with and without blood flow restriction ( BFR). Middle-aged (42-62 years) men ( n = 12) and women ( n = 6) completed 18 sessions of unilateral knee extensor resistance training to volitional fatigue over 6 weeks. One limb trained under BFR, and the contralateral limb trained without BFR [free flow ( FF)]. Before and after the training, measures of anterior and lateral quadriceps muscle thickness ( MTh), strength, power and endurance were assessed on each limb. The total exercise training volume was significantly greater for the FF limb compared with the BFR limb ( P<0·001). Anterior quadriceps thickness and muscle function increased following the training in each limb with no differences between limbs. Lateral quadriceps MTh increased significantly more ( P<0·05) in the limb trained under BFR ( BFR: 3·50 ± 0·61 to 3·67 ± 0·62 cm; FF: 3·49 ± 0·73 to 3·56 ± 0·70 cm). Low-load resistance training to volitional fatigue both with and without BFR is viable options for improving muscle function in middle-aged individuals. However, BFR enhanced the hypertrophic effect of low-load training and reduced the volume of exercise needed to elicit increases in muscle function. [ABSTRACT FROM AUTHOR]