Resistance exercise training for skeletal muscle health in adults living with multiple long-term conditions: a scoping review

Low muscle strength is prevalent in individuals living with multiple long-term conditions (MLTC). Resistance exercise (RE) training is the most effective treatment for improving strength and physical performance across the lifecourse, but little is known about RE in people living with MLTC. This scoping review aimed to identify published evidence on RE as a treatment for improving muscle mass, strength and physical performance in adults living with MLTC. Six electronic databases were searched to identify studies that included adults aged >18 years who were living with two or more long-term conditions and undertaking a RE intervention. Sixty-eight studies met the inclusion criteria. A range of methods for characterising MLTC were reported; almost half of the studies (30/68) that included people living with ≥2 LTC focused on co-morbidity (i.e., participants selected based on the presence of an index condition plus one or more co-existing conditions). Only seven studies specifically described their population as living with MLTC. Most studies involved RE within a multicomponent intervention with considerable variability in exercise programming. Of the studies which assessed lean mass or muscle mass (n=17), only one reported a post-intervention increase. Muscle strength improved in 47% (16/34) of studies that examined this, with improvements in physical performance reported across most studies (82%). Exercise session attendance was generally good with few reported adverse events. RE training may be effective for improving strength and physical performance in adults living with MLTC. Importantly, RE was well tolerated with good adherence and low numbers of adverse events reported.