Does Cardio Burn Muscle?

Cardio. Some of us love it, and some (most) of us hate it! We all have our reasons to love and hate cardio. Related, check out our answer to the best cardio machine for burning calories.

A question you have probably asked is will performing cardio negatively affect your muscle gains?

Well, this article aims to give you the answer to that question as well as some suggestions for the best type of cardio to for building and maintaining muscle mass.

does cardio burn muscle

Cardio Muscle Burning Myths

It cannot be argued that regular cardio training can have tremendous health benefits, fitness advantages and can be a key tool for staying lean.

It’s a great way to burn off some unwanted fat, but is it burning some of your hard-earned muscle too? Here are a couple of the common viewpoints about cardio and muscle gains.

1. Skinny people do cardio

People who perform considerable amounts of cardio, for example, a high-level runner, is typically a light build and doesn’t hold a lot of muscle.

This is by choice, they eat and train accordingly to maintain this physique since it helps them to perform at their best.

Anybody that highlights examples of cardio-enthusiasts being skinny has got it the wrong way around. The cardio itself isn’t necessarily making them skinny, they maintain that shape to make the cardio easier for themselves.

musclular cyclist

Cardio doesn't seem to have hampered this guy's muscle building efforts much

2. Cardio will burn all your gains

You may hear of professional or aspiring bodybuilders telling people about their ‘worst nightmare’ of losing all their muscle leading up to a show or competition as a result of too much cardio.

This is not solely down to cardio and, in a lot of cases, it has nothing to do with cardio in and of itself!

The cause of muscle loss is generally down to poor diet and nutrition protocols. Failing to consume the correct amount of Carbohydrates, Fats, and Protein.

The second big mistake people make with their cardio is choosing the wrong type.

This can be categorised by selecting inferior mode of cardio as well as the wrong intensities. More on this later.

Benefits of Cardio for Body Composition

As long as you program it correctly (again, more on this at the end), cardio should not have any actual negative affects on your body composition. In fact, there are some nice benefits to be had for those who perform cardio regularly alongside their lifting.

Cardio Improves Recovery

Now, while there don’t seem to be many (if any) studies confirming the reasons for it, from the experience of myself and many other lifter, it is generally agreed performing cardio on a regular basis aids recovery.

This study shows also shows a positive correlation between moderate-intensity aerobic work when performed after soreness-inducing exercise.

How can cardio improve recovery?

It can be theorised cardiovascular exercise improves your body’s overall blood circulation due to the sustained increase in heart rate.

Moreover, Increasing the blood flow to a specific area in your body, should increase blood supply to that area and boost its’ recovery.

For example, if you have completed a lower body weights workout, adding some moderate-intensity cardio such as a cycling to the end of your workout.

This should increase blood flow to the area and help the delivery of nutrients as well as flushing out “waste products” that are left because of the repeated muscle contractions during weight training.

By reducing the effect of delayed onset muscle soreness (DOMS), you should be able to train more regularly and at a higher level in each workout.

Important for maintaining and building muscle mass.

Increases total work capacity

Performing cardio on a regular basis will increase both your anaerobic and aerobic capacity, in other words, it will allow you to do more total work without feeling fatigued and to recover more efficiently from that work.

Of course, being able to do more in general can definitely help with you muscle building efforts.

Cardio is not just for cutting

Here’s a common scenario among bodybuilders:

During your “offseason” or “bulk”, you lay off the cardio to increase your size, lifting heavy and reducing the number of reps you perform during workouts. This is a great approach for adding muscle mass to your frame.

However, your work capacity and stamina are going to take a hit.

But, who cares, right? It’s all about gains!

Well, not only are you missing out on the benefits already covered earlier, you could well be making it harder for yourself when it comes time to cut down?

Your work cardiovascular fitness may be so low that you need to spend weeks just building that back up before it even becomes truly effective for fat loss.

Performing cardio all year around, even if it is only to maintain a base level of fitness during a gaining phase, will make it much easier to transition into doing more cardio work when the time comes to burn some extra calories.

Best type of cardio for building and maintaining muscle

Earlier, I alluded to the fact that many people suffer negative effects by choosing the wrong mode of cardio and/or the wrong intensity.

So, what is the best way to do cardio without losing muscle?

Firstly, selecting the best type is key. 

There are so many different modes of cardio training for you to choose, which makes it near impossible to examine the effects of each one individually.

However, there has been one important study done in 2009, which compared to cycling to treadmill endurance and their effects on both strength and muscle size.

Cycling was found to be superior for maintaining muscle mass. This is likely down to the lower impact nature and reduced eccentric demand of cycling.

Therefore, choosing a lower impact mode of cardio like cycling is probably the way to go. Btw check out our top 10 Tredmill guide here.

Secondly, you must pay attention to the intensity of your cardio.

To be honest with you, almost any cardio method is going to work for dropping bodyfat. All it takes is calorie burn.

What we are looking for is the most efficient and least detrimental method of cardio for you muscle levels.

With this is mind, it is clear that interval style training is superior. Not only is it much more time-efficient but it has been shown to be superior for muscle mass maintenance, as shown in this study.

4-10 rounds all-out effort sprints lasting 10-30 seconds is a solid protocol for fat burning cardio without sacrificing muscle. I like to keep recovery time relatively high with these sprints to allow for full effort on each one. 1-2 mins recovery between each is good.

Best time to do cardio?

As mentioned earlier on, it may be beneficial for recovery purposes to add some low to moderate-intensity cardio in after a workout.

However, for your fat burning cycling intervals, it is likely best to leave them away from your lower body training.

This study suggests that same-day endurance training may impede strength gains, which could damage muscle gains in the longer term.

This does seem to be specific to the muscle groups used so you could still perform your intervals after a lower body workout, but the mode of cardio would need to change to something upper body dominant. An example could be battle ropes.


The key takeaway from this article is that cardio will not burn your hard-earned muscle as long as you program it correctly. Resistance training and endurance training combined are superior for body composition than performing either of them in isolation.

Don't get me wrong here. In the short term, extra cardio is probably going to decrease the amount of muscle you are building by a small amount.

However, I believe over the long-term it will benefit your body composition and health as a whole.

Follow these guidelines and you will be good to go:

Cardio for Muscle Building Strategy

Perform high intensity intervals of 10-30 seconds with rest periods of 1-2 minutes.

Choose a lower impact mode of cardio such as a spin bike.

Do not work the same muscles during your weight training and high intensity cardio on the same day.

Consume a diet that supports the amount of activity you are performing along with your goals. If you find yourself losing a great deal of muscle, you are probably eating too few calories.

Denver Matheson

I spend a lot of time at the gym and even more time in the kitchen giving my body what it needs to repair itself and grow stronger. The third most important place for any athlete is their research zone. That's exactly why this site exists, to help me share all of the information I've learned throughout the years just like people did for me in the first place!

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