Dose–response effects of resistance training on physical function in frail older Chinese adults: A randomized controlled trial

Background Effective exercise for the frail elderly has been found to contribute to healthy aging; the corresponding relationship between intensity and volume of exercise and health effects remains unclear. The present study aimed to investigate the dose–response effects of resistance training on muscle strength and physical fitness in frail older adults. Methods In this randomized controlled trial, participants were randomized into seven groups: moderate‐volume low‐intensity, moderate‐volume moderate‐intensity, moderate‐volume high‐intensity, high‐volume low‐intensity, high‐volume moderate‐intensity, high‐volume high‐intensity and routine care, receiving 12 weeks of resistance training of different intensities and volumes of exercise. The outcomes were muscle strength (assessed by ergonomics force gauges) and physical fitness function (assessed by the 6‐min walking test [6MWT], the 30‐s sit‐to‐stand test [30sSTST] and the 8‐foot up‐and‐go test [8‐FUGT]) before and at 6 and 12 weeks of intervention. Results A total of 161 participants completed the exercise intervention. There were no significant differences in age, sex, height, body weight and body mass index among the seven groups. The exercise volume of resistance training showed linear relationships with muscle strength of the lower limbs, 30sSTST and 6MWT results and a non‐linear relationship with 8‐FUGT. Resistance training intensity was found to have a linear relationship with muscle strength of the lower limbs and 6MWT and non‐linear relationships with 30sSTST and 8‐FUGT. The mixed linear model analysis revealed that the lower limb muscle strength differed significantly before and during the intervention (W = 8571.5, Padj