AUTHOR=de Queiros Victor Sabino , de França Ingrid Martins , Trybulski Robert , Vieira João Guilherme , dos Santos Isis Kelly , Neto Gabriel Rodrigues , Wilk Michal , Matos Dihogo Gama de , Vieira Wouber Hérickson de Brito , Novaes Jefferson da Silva , Makar Piotr , Cabral Breno Guilherme de Araújo Tinoco , Dantas Paulo Moreira Silva 

TITLE=Myoelectric Activity and Fatigue in Low-Load Resistance Exercise With Different Pressure of Blood Flow Restriction: A Systematic Review and Meta-Analysis

JOURNAL=Frontiers in Physiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2021.786752

DOI=10.3389/fphys.2021.786752

ISSN=1664-042X

ABSTRACT=<p><bold>Background:</bold> Low-load resistance exercise (LL-RE) with blood flow restriction (BFR) promotes increased metabolic response and fatigue, as well as more pronounced myoelectric activity than traditional LL-RE. Some studies have shown that the relative pressure applied during exercise may have an effect on these variables, but existing evidence is contradictory.</p><p><bold>Purpose:</bold> The aim of this study was to systematically review and pool the available evidence on the differences in neuromuscular and metabolic responses at LL-RE with different pressure of BFR.</p><p><bold>Methods:</bold> The systematic review and meta-analysis was reported according to PRISMA items. Searches were performed in the following databases: CINAHL, PubMed, Scopus, SPORTDiscus and Web of Science, until June 15, 2021. Randomized or non-randomized experimental studies that analyzed LL-RE, associated with at least two relative BFR pressures [arterial occlusion pressure (AOP)%], on myoelectric activity, fatigue, or metabolic responses were included. Random-effects meta-analyses were performed for MVC torque (fatigue measure) and myoelectric activity. The quality of evidence was assessed using the PEDro scale.</p><p><bold>Results:</bold> Ten studies were included, all of moderate to high methodological quality. For MVC torque, there were no differences in the comparisons between exercise with 40–50% vs. 80–90% AOP. When analyzing the meta-analysis data, the results indicated differences in comparisons in exercise with 15–20% 1 repetition maximum (1RM), with higher restriction pressure evoking greater MVC torque decline (4 interventions, 73 participants; MD = −5.05 Nm [95%CI = −8.09; −2.01], <italic>p</italic> = 0.001, <italic>I</italic><sup>2</sup> = 0%). For myoelectric activity, meta-analyses indicated a difference between exercise with 40% vs. 60% AOP (3 interventions, 38 participants; SMD = 0.47 [95%CI = 0.02; 0.93], <italic>p</italic> = 0.04, <italic>I<sup>2</sup></italic> = 0%), with higher pressure of restriction causing greater myoelectric activity. This result was not identified in the comparisons between 40% vs. 80% AOP. In analysis of studies that adopted pre-defined repetition schemes, differences were found (4 interventions, 52 participants; SMD = 0.58 [95%CI = 0.11; 1.05], <italic>p</italic> = 0.02, <italic>I</italic><sup>2</sup> = 27%).</p><p><bold>Conclusion:</bold> The BFR pressure applied during the LL-RE may affect the magnitude of muscle fatigue and excitability when loads between 15 and 20% of 1RM and predefined repetition protocols (not failure) are prescribed, respectively.</p><p><bold>Systematic Review Registration:</bold> [<ext-link ext-link-type="uri" xlink:href="http://www.crd.york.ac.uk/prospero" xmlns:xlink="http://www.w3.org/1999/xlink">http://www.crd.york.ac.uk/prospero</ext-link>], identifier [CRD42021229345].</p>