Development of a home based resistance exercise programme for muscle strength and function during weight loss

Abstract

Thesis abstract Background The prevalence of obesity continues to increase, representing a major public health concern across the globe. While dietary interventions can reduce body mass, the concurrent loss of fat free mass and muscle strength is a potentially deleterious consequence. Resistance exercise may help preserve muscle mass and function during weight loss, yet its implementation remains challenging. This thesis investigated the potential of home-based resistance exercise to attenuate these deleterious effects of weight loss through three research studies.

Methods Study 1 included a systematic review and meta-analysis examining the effects of resistance exercise on body composition, muscle strength, and cardiometabolic health during dietary weight loss. Study 2 employed qualitative methods to explore experiences and perceptions of resistance exercise among people living with overweight or obesity (n=11), informing a theory of change for intervention development. Study 3 evaluated the effects of a 12-week home-based resistance exercise intervention, during dietary weight loss, through a randomised controlled pilot trial (n=48).

Results The systematic review and meta-analysis (25 RCTs) demonstrated that supervised resistance exercise during dietary weight loss preserved fat free mass (SMD: 0.40, p<0.001), increased fat mass loss (SMD: -0.36, p<0.001), and improved muscle strength (SMD: 2.36, p<0.001) relative to a no exercise control. The qualitative study identified multiple barriers, including pandemic-related limits, access to facilities and financial constraints to traditional gym-based resistance exercise, and indicated strong preferences for home-based alternatives. The pilot trial showed that, during weight loss, home-based resistance training improved grip strength (p=0.046), knee extensor maximal voluntary contraction force (p=0.019) and sit-to-stand performance (p<0.001), but did not have any effects on body composition (body mass index, total body mass, fat mass, fat free mass, muscle thickness) compared to dietary weight loss alone.

Conclusions The current thesis demonstrates that supervised resistance exercise enhances the benefits of diet induced weight loss by preserving muscle mass and improving muscle function. The development and evaluation of a home-based programme showed promising results for overcoming traditional barriers to resistance exercise participation and improving muscle strength and function, but not muscle mass. These findings support the implementation of accessible resistance exercise interventions during weight loss for people living with overweight or obesity.