Figure 1. Impact of obesity in old age on skeletal muscle function. Excessive adiposity in old age causes a significant reduction in contractile performance in humans (A). Less is known about how obesity in old age affects muscle quality (force or power relative to muscle mass), so usage of an isolated muscle model can provide information about the contractile performance of isolated respiratory (B) and locomotor (C) skeletal muscles, otherwise difficult to examine in vivo (observations from Hill et al., 2019). Whilst the studies of in vivo and in vitro muscle performance do not reciprocate one another, the overall consequence of the altered contractile performance of old obese skeletal muscles is a poorer quality of life. ADL, Activities of daily living. Images from BioRender.