er, what about the second experiment, where light exercise reduced infection to 12% versus 50% for no exercise and 70% for 5x as much exercise?

that seems to suggest that doing a little bit of work keeps the body healthy.

furthermore, the study doesn't say what the mice did before the experiement. perhaps the mice were used to 20-30 minutes of exercise a day, and it is change that is most damaging. what one mice considers exhausting, another mouse might find boring.

edit: the article mentions "(Although definitions of intense exercise vary among researchers, most define it as a workout or race of an hour or more during which your heart rate and respiration soar and you feel as if you are working hard.)"