How Much Exercise Is Too Much? Plus, How To Know Your Limit

On a new workout kick? Whether you're training for a marathon, packing in extra yoga classes, or dedicating more time to strength training, you've probably asked yourself this question: How much exercise is too much?

"You can do literally unlimited amounts of moderate-intensity exercise, and you won't hurt your body," she explains. So daily walking, daily yoga, or daily moderate weight training is A-OK. "But when it comes to the high-intensity stuff, that's when people start to break," she explains. 

More specifically, "If you go over 150 minutes of high-intensity interval training a week, you'll damage your mitochondria," she explains. She references a 2021 study in which researchers found mitochondrial impairment and even increased glucose intolerance1 in those who spent more than five hours a week doing HIIT exercise. (150 minutes is only about 2.5 hours, but Maloof would consider it the potential point of diminishing returns. Think of five hours as the absolute limit.)

Of course, each one of these signs could also be linked to another factor, like how much sleep you get, your diet, medications, etc. But if you recently picked up more exercise than usual and you begin to reflect a few of the above signs, then you may want to experiment with a pared-back workout plan. 

For those who participate in high-intensity interval training, capping your workouts at five hours a week max is the best way to protect the mitochondria of your cells and reduce feelings of lethargy.