Does Running Burn Muscle?

Dear Davey,

You mentioned that longer runs can have a negative effect on muscle growth. Can you elaborate? I’m an avid runner and I typically run for long amount of time.

Thanks,
Chris

Dear Chris,

Though many people mistakenly believe otherwise, cardiovascular exercises like swimming, running or biking – when done in moderation – will not cannibalize your strength training results. The keyword being moderation.

In fact, a study done at West Virginia University and published in the “Journal of the American College of Nutrition” demonstrated that people who strength train regularly don’t lose muscle mass while performing cardio – even while on calorie restricting diets. That’s great news!

In general, your body won’t use your muscles as a source for fuel. The only exception would be during periods of extreme endurance cardio training. In other words, if you run or swim or bike for a long period of time, and if your glycogen or carbohydrate stores become depleted, your body will turn to the amino acid proteins in my muscles as a last resort – and it will turn those proteins into glucose for fuel.

To avoid this, it’s obviously important to keep your body fueled with plenty of complex carbohydrates. Or, even better, eliminate the risk altogether by keeping your cardio sessions short, intense and efficient.

The other issue is cortisol. As I’ve mentioned before, cortisol is hormone that your body releases when it is under stress. The effect of cortisol on muscle mass isn’t pretty. Cortisol is a catabolic hormone that reduces protein synthesis and may prevent muscle growth. In addition to stunting your results, cortisol has also been linked to increased fat retention in your body’s midsection.

Many things can stress your body, and a long cardio session is certainly one of them. For this reason, many trainers will encourage clients to limit cardio sessions to less than 45 minutes. It’s worth noting that long strength training sessions can also lead to the release of cortisol. In other words, more time at the gym isn’t always better.

To get a short but powerful workout, I recommend high intensity interval training. It can be used for both cardio and strength training, and it’s the basis for my Get Ripped Workout program. Most of my cardio sessions, thanks to high intensity interval training, are only 15 minutes long. It’s an intense 15 minutes, but it gives me the results that I want.

If you really love long runs, then it’s fine to run long distances as an occasional treat – but it certainly shouldn’t be the backbone of your cardio workout. And a few hours prior to your long run, fuel your body with plenty of complex carbs. I hope that helps!

Love,
Davey

About Davey Wavey

Davey Wavey is a certified personal trainer and YouTube sensation with more than 250 million video views. For Davey's fitness tips and secrets, sign up for his free monthly newsletter - or download any of his affordable and effective workout programs.

Comments

  1. li chun hon says:

    as i know, muscles are made up of protein, and our body uses protein only as the last resort for energy source. only staving for days will make muscles deplete. is that true??

  2. Spot on – that was the info I was looking for! Thanks, Davey.

  3. christopher says:

    this is good news-as my cardio is 30 mins-in duration-daily.

  4. So… if you were to down your carbohydrate intake and up the protein, and were to run more, you would burn some of the muscle mass? (I know it would raise cortisol levels, but I’m just speaking in hypothetical terms.)

  5. Hi, I thought this was a nice blog. Apreciate you sharing.