Resistance Exercise and Skeletal Muscle-Related Outcomes in Patients with Cancer: A Systematic Review.

ABSTRACT

BACKGROUND: Skeletal muscle loss is prevalent throughout the cancer continuum and correlates with morbidity and mortality. Resistance exercise has been trialed to mitigate skeletal muscle loss. This systematic review summarizes and qualitatively synthesizes the effects of resistance exercise on muscle-related outcomes in adult cancer populations, including skeletal muscle mass, performance and muscle-related biomarkers. METHODS: The systematic review protocol was developed in accordance with the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P). We searched electronic databases including AMED, CENTRAL, CINAHL, CIRRIE, EMBASE, MEDLINE, PEDro, REHABDATA, Scopus, and SPORTDiscus (from inception to December 2021).We included randomized controlled trials that investigated the effects of resistance exercise on muscle-related outcomes in adult cancer populations. Interventions that involved any resistance exercise were included. Muscle-related outcomes were categorized as skeletal muscle mass (e.g., lean mass, appendicular muscle mass), muscle performance (e.g., muscle strength, physical function), and muscle-related biomarkers (e.g., muscle cells, metabolic/inflammatory markers). Risk of bias (RoB) was assessed using the Cochrane ROB tool. RESULTS: 02 studies from 101 randomized controlled trials were included. The majority of studies focused on breast cancer (46%) and those who completed treatment (43%). Resistance exercise interventions were largely 3-4 months long (48%), combined with aerobic exercise (56%), at a vigorous intensity (25%), and in-person/supervised settings (57%). Among the studies that assessed muscle mass, performance, and biomarkers (n = 42, 83, and 22, respectively), resistance exercise interventions improved upper/lower body or appendicular muscle mass (67-100%), muscle strength (61-68%), and physical function (74-100%). Most biomarkers did not show significant changes (75-100%) or showed inconsistent results. CONCLUSIONS: Generally, resistance exercise had positive effects on skeletal muscle mass and performance with an absence of negative effects compared to controls. Our findings demonstrated that resistance exercise may be an effective strategy to attenuate deterioration or exert improvements in muscle mass and performance outcomes.