Muscular adaptations to low-load resistance training to repetition failure with and without blood flow restriction

Blood flow restriction during resistance exercise is an effective method for increasing muscular size and strength. However, skeletal muscle adaptations to low-load resistance exercise (LL-RE) and low-load blood flow restriction resistance exercise (LL-BFR) performed to repetition failure are lacking. Whole-body and skeletal muscle physiological outcomes were measured following 6-weeks of LL-RE and LL-BFR training to repetition failure using a within-subject design. Similar muscle strength and size outcomes occurred despite lower total exercise volume with LL-BFR. Both groups increased power output during the first-third of an endurance task and only LL-BFR training sustained a greater power output during the midpoint by 18%. Capillary contacts of type I muscle fibers increased similarly for both groups and only LL-RE training increased mitochondrial respiratory capacity by 20%. Overall, differences in muscle fatigue between LL-RE and LL-BFR may exist and are not explained by muscular strength and size or muscle microvascular and mitochondrial properties.