Fig. 1.

A theoretical construct outlining the relationship between physical inactivity levels and muscle metabolic health. It is proposed exercise will produce significant physiological stress on muscle to produce positive gains in muscle strength, protein synthesis and insulin sensitivity, but this exercise stress will be relatively short lived. In comparison, physical inactivity will impose opposing physiological signals of smaller magnitude, but these signals will persist for considerably longer durations in sedentary individuals and will induce muscle level adaptations that persist as long as inactivity is present resulting in relatively quick (hours to days) negative adaptation.