The way you live—like how much you move, how you manage stress, and what you eat—can turn your genes up or down without changing your DNA, kind of like a dimmer switch for your body’s instructions.

This study found that doing intense exercise changes how your muscle genes work, and those changes stick around even after you stop exercising—proving that exercise can turn genes on or off without changing your DNA code.

This study found that working out changes how our genes behave without changing the genes themselves — like flipping switches on our DNA — which is exactly what the claim says exercise can do.