Exercise changes how your genes are expressed

A single bout of aerobic exercise alters the expression of over 700 genes within hours — including genes involved in fat metabolism, inflammation, and insulin sensitivity. These epigenetic changes don't alter the DNA sequence itself but switch genes on or off, and many persist for days after exercise. This means the benefit of a morning run extends far beyond the run itself, reprogramming cell behaviour for the rest of the day.

Source: Barres, R. et al., 'Acute Exercise Remodels Promoter Methylation in Human Skeletal Muscle', Cell Metabolism (2012)