Does Cardio Burn Muscle? Here’s the Truth


One of the most hotly contested issues in the world of fitness is whether or not cardio will hinder your progress with regards to building muscle.

The conversation has been had in gyms all over the world, and will be had for years to come, so it’s time for us to add our two cents.

It’s true, cardio can burn muscle, but not always. This may be frustrating, but there aren’t many black and white issues in fitness. If you overdo your cardio training, your muscles might suffer, but there are ways to juggle cardio and strength training.

If you have strength and fitness goals, then there’s a strong chance that at one point or another you’ve wondered whether you can combine cardio and strength training to achieve even greater results.

If Is it possible to build lean muscle while also improving your cardiovascular endurance? 

In other words, does cardio make you lose muscle? 

That’s the question we want to explore in depth in this article, and it’s one that pervades the fitness community, hanging around like a bad smell.

If you want a concise answer, here’s the best we have to offer: yes, cardio can burn muscle, but if you commit to your nutrition and weight training then this shouldn’t be a problem.

The main issue here then is not so much whether or not cardio will burn muscle, but to what extent it will and how much of it you have to do to decrease muscle mass.


Let’s dive straight in!

What is Cardio?

To explore this question thoroughly, we first need to have a solid grasp of the component parts.

Let’s go back to basics and find out exactly what cardio is before we look at the process of building muscle.

Cardio, short for cardiovascular, is a form of exercise that involves getting the heart rate up. Anything that leaves you short of breath can likely be considered a form of cardio, though it’s the activities that have you red in the face and dripping with sweat that are the most effective such as the following:

  •  Running 
  •  Cycling 
  •  Swimming 
  •  HIIT (High Intensity Interval Training)

The main purpose of cardio, aside from improving your heart health and other health benefits, is to burn off excess calories in order to lose or maintain weight.

This is where the problem lies: muscles need calories in order to grow.

So does that mean by depriving your body of those extra calories through cardio, you are starving your muscles’ fuel supply?

Yes, but this can be offset with proper nutrition, which we’ll get into later.

Does cardio burn fat or muscle, you might also ask, and the answer is that it will first eat into your fat stores before it starts to diminish muscle mass.

How Do You Build Muscle?

So now we have a general idea of what cardio is and how it can improve your health and fitness, let’s focus on the process of building muscle.

The only way to consistently build muscle is to constantly challenge the muscles of the body using some form of weight or resistance. This doesn’t always look like the gym enthusiast pumping iron every day, as you can also build muscle through your day job if you work in the field of manual labor.

The process of breaking down the muscles continually in this way is referred to as muscle hypertrophy. This what happens when you damage the muscle fibers. In repairing these muscle fibers, the body develops more muscle mass as a response.

The rate at which you build muscle and how much muscle you can realistically put on will likely be determined by a variety of genetic factors such as your body type.

So does cardio interfere with the process of muscle hypertrophy? 

Does cardio after weights affect muscle growth?

Well, it’s possible, but there is one key benefit cardio exercise provides that will help you make even more muscle gains: it can reduce the risk of injury and boost your overall level of fitness.

The problem seems to be that when you commit to a strict regime of cardio training, your muscles suffer. If you run cross country 4-5 times a week, then you’re likely going to cause a knock-on impact on your muscles.

It seems that long endurance training is what causes a loss in muscle, as well as poor nutrition, which we’ll get to now.

How to Prevent Muscle Loss During Cardio

One of the biggest mistakes people make when they start doing cardio exercise to supplement their strength training regime is they don’t adjust their nutrition to account for this extra exercise.

If, for example, you have been lifting weights in the gym for three months and then you decide to add 3-4 runs a week to your schedule, you’re going to need to add extra calories to your diet. Fail to do so, and the cardio exercise you do will likely burn off some of the calories your muscles need to grow.

The main dietary factor to bear in mind if you want to prevent muscle loss during cardio is making sure your macros (macronutrients) are spot on.

The most important macronutrient for working out, as we’re sure you’re already well aware, is protein.

As a result, if you’re trying to juggle cardio and strength training at the same time it’s imperative that you’re getting enough protein in your diet.

Once you’re content that you have enough calories to build muscle, focus on getting protein from good sources such as meats, dairy, and protein powder if necessary. This will help your muscles with the reparation process and prevent them from shrinking in size as a result of the cardio exercise.

Basically, what we’re saying is you need to strike a balance.

It’s not only nutrition you need to be mindful of, either, but it’s also a case of how much cardio exercise you do versus how much strength training you do.

Sure, you can build a lean muscular physique by running every day and hitting the gym to lift weights twice a week, but you will likely limit your muscle gains if you take this approach.

If instead you opt to hit the gym five days a week and perform light cardio two to three times a week then you will be able to build more muscle while potentially also losing fat.

Frequently Asked Questions About Cardio

Can you build muscle and do cardio?

Yes, you absolutely can both build muscle and do cardio at the same time.

While cardio may not be as effective as traditional strength training methods such as weightlifting for building muscle, it can be a good form of supplementary exercise.

Doing cardio in moderation shouldn’t affect your muscle gains, provided you are eating well and staying on top of your lifting routine.

Does cardio cause muscle loss?

Not necessarily, but if you do a lot of cardio in proportion to strength training then you may see a negative impact on your muscles.

It’s a common misconception that purely by going on a run or for a swim once a week you are compromising the muscle you built in the gym, but the truth is less black and white.

Some studies even show that cardio can help improve the size of your muscles, so it all depends on what approach you take and how well you can spin the various plates of exercise.

Should I do cardio everyday?

While it isn’t necessary to perform a cardio workout every day, there’s nothing stopping you from doing so.

It all depends on what your strength and fitness goals are.

If your goal is to build cardiovascular endurance, then by all means go on a run every morning, but if your primary goal is to develop muscle mass then you may want to limit your cardio somewhat.

A Final Word From Energetic Lifestyle

The age old debate surrounding cardio and strength training won’t be settled definitively any time soon, but we hope you feel a bit more confident weighing in on the discussion now.

As with most things, the key is to do refrain from doing things in excess, and that way you should be able to strike a good balance.

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Article by:

Energetic Lifestyle Team

Our detailed review has been contributed to by multiple members of the Energetic Lifestyle Review Team to ensure the best research and highest standard of quality. Have a good or a bad experience with one of the products? Please let us know, we love the feedback!

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