Relationship between sedentary behaviour, physical activity, muscle quality and body composition in healthy older adults

SIR—Sedentary behaviour (SB), defined as time spent sitting or lying, has been shown to be a major modifiable risk factor for chronic disease, disablement and frailty [1] independently physical activity levels (PA) [2, 3]. Time spent sitting or lying affects muscle physiology [4], is thought to accelerate sarcopenia [5], and to be a determinant driver of the obesity epidemic [6]. These two effects of SB: obesity and low muscle strength appear to potentiate each other to increase risk of disablement and frailty in older adults [7].