Cardio Won’t Kill Your Gains—As Long As You Do This

When he became the fastest American marathon runner with a 2:04:58 at the 2011 Boston Marathon, Ryan Hall weighed around 130 pounds and was as lean as a whippet. Now, Hall is nearing 200 and most of that new weight is muscle.

What changed? Hall retired from professional running in 2016. The short version of Hall’s story seems to confirm an oft-asked belief that cardio kills gains. But experts say it’s more complicated than that.

Casual running has been the beacon of weight-loss exercise since the jogging boom of the ’70s so it makes sense that it could be counterproductive if your goal is bulking up. Scientific studies—like this classic (and extremely old) one—seem to back up the idea. These don’t paint a complete picture though; if they did, researchers and trainers wouldn’t still be asking the question.

After sifting through newer studies and three experts, we waded through the nuance so you don’t have to. Hall, by the way, still does cardio. In fact, he recommends it (and he can still run a five-minute mile).

Tom Oddo, D.C., C.S.C.S., C.E.A.S. is the owner of City Integrative Rehabilitation in New York City.

Jenna Stangland, M.S., R.D.N., C.S.S.D., L.D.N., C.L.T. is a registered dietitian and specialist in sports dietetics.

Nichele Cihlar is a strength and conditioning coach and the director of training at GORUCK.

The short answer is no. The experts we spoke with agree that cardio doesn’t interfere with muscle growth in nearly all cases. Even in the exceptional cases that it does, strength training and cardio can dovetail nicely into a complete fitness program with proper nutrition and workout phasing (when you divide your workouts into mini three- to four-week cycles that have different goals).