Low-load resistance training to task failure with and without blood flow restriction: muscular functional and structural adaptations

Abstract

The application of blood flow restriction (BFR) during resistance exercise is increasingly recognized for its ability to improve rehabilitation and for its effectiveness in increasing muscle hypertrophy and strength among healthy populations. However, direct comparison of the skeletal muscle adaptations to low-load resistance exercise (LL-RE) and low-load BFR resistance exercise (LL-BFR) performed to task failure is lacking. Using a within-subject design, we examined whole muscle group and skeletal muscle adaptations to 6 wk of LL-RE and LL-BFR training to repetition failure. Muscle strength and size outcomes were similar for both types of training, despite ~33% lower total exercise volume (load × repetition) with LL-BFR than LL-RE (28,544 ± 1,771 vs. 18,949 ± 1,541 kg, P = 0.004). After training, only LL-BFR improved the average power output throughout the midportion of a voluntary muscle endurance task. Specifically, LL-BFR training sustained an 18% greater power output from baseline and resulted in a greater change from baseline than LL-RE (19 ± 3 vs. 3 ± 4 W, P = 0.008). This improvement occurred despite histological analysis revealing similar increases in capillary content of type I muscle fibers following LL-RE and LL-BFR training, which was primarily driven by increased capillary contacts (4.53 ± 0.23 before training vs. 5.33 ± 0.27 and 5.17 ± 0.25 after LL-RE and LL-BFR, respectively, both P < 0.05). Moreover, maximally supported mitochondrial respiratory capacity increased only in the LL-RE leg by 30% from baseline ( P = 0.006). Overall, low-load resistance training increased indexes of muscle oxidative capacity and strength, which were not further augmented with the application of BFR. However, performance on a muscle endurance test was improved following BFR training.

The blood flow restriction training effect in knee osteoarthritis people: a systematic review and meta-analysis

“…For that matter, a current research comparing BFR training and LLT over 6 weeks, showed the volume of the training to be 33% lower and results favorable to BFR group, but without any statistically significant value. 35 The American Academy of Orthopedic Surgeons -AAOS, the Osteoarthritis Research Society International -OARSI, and the American College of Rheumatology explain that strength increment promotes pain reduction, in addition to attenuating symptomatology, reducing joint damage progress [36][37][38] on individuals with knee osteoarthritis. It was observed that all osteoarthritis patients interventions are due to neural activation and increased quadriceps strength, since these subjects have decreased this musculature strength due to arthrogenic muscle inhibition.…”

Human Skeletal Muscle Mitochondrial Adaptations Following Resistance Exercise Training

“…Additionally, the authors observed a significant increase in citrate synthase activity and state 3 respiration rates in normoxic resistance training environment, which again suggests that resistance training in lieu of hypoxia may not stimulate appreciable mitochondrial adaptations. Others have also investigated the effects of low-load resistance training (with or without blood flow restriction) to failure for six weeks in a within-subject design [66]. Both legs had similar muscle strength and size increases.…”

Resistance training combined with blood flow restriction in cirrhosis: study protocol for a randomized controlled trial

“…To our knowledge, this will be the first intervention study to investigate BFR-RT in this population. Considering that current evidence shows BFR-RT is a safe method, even for frail populations [15,17,18], we believe BFR-RT will result in important increases in muscle mass and strength, accompanied by increases in functionality, with no negative outcomes on cirrhosis condition. There are some limitations to this study.…”

“…In this sense, evidence shows that low-load RT combined with partial blood flow restriction (BFR-RT) results in significant muscle mass gains, comparable to high-load RT [15,16] or low-load RT to muscle failure [17]. Its applicability in frail populations (e.g., elderly and cardiac patients) also has been verified, with positive outcomes after the intervention period [15,18,19], including functional performance [20].…”