does cardio burn muscle

Do you avoid or severely limit the amount of cardio you perform during the week out of fear that it will “burn muscle” and interfere with your size and strength gains?

You’re not alone.

After all, cardiovascular exercise eats away at your muscle tissue, decreases gym performance and is directly counterproductive to building a strong and muscular body, right?

Well, not quite.

Just like most bodybuilding and fitness topics, the answer here is not black and white, and it’s most certainly not an issue of cardio being either “good” or “bad” or that you should either perform a ton of cardio throughout the week or none whatsoever.

Instead, the answer lies on a bell curve where performing some cardio is totally fine and will produce certain health and fitness benefits, but to where performing too much can begin having a negative impact on your muscle building progress if you aren’t careful.

In this post I’ll explain the real relationship between cardio and muscle growth, and I’ll show you the optimal way to implement cardio into your weekly routine so you can build the head-turning physique you’re after while optimizing your physical and mental health at the same time.

Let’s get to it…

The Negative Effects Of Performing Excessive Cardio

too much cardio

Let’s start with the possible downsides here.

Yes, cardio can certainly deliver a variety of valuable benefits when performed consistently, but going too far overboard is not a wise idea if you’re looking to build muscle and gain strength as effectively as possible.

There are a few reasons why performing too much cardio is not a good thing…

1) It interferes with recovery in between weight training sessions.

Remember, the work you perform in the gym is simply the “spark” that sets the muscle building process into motion.

The real magic happens while you’re out of the gym eating and resting, as that’s the time when the muscles are being rebuilt larger and stronger in preparation for the next workout.

When it all comes down to it, recovery is growth.

This is why your cardio volume and frequency needs to be moderated, since every cardio session you perform is another overall stressor to the body that you’ll need to recover from.

A moderate amount of cardio can actually improve muscle recovery when performed within certain limits (I’ll touch on this later), but there eventually comes a point of diminished returns to where the extra cardio begins working against you rather than for you.

This is especially true of the higher intensity interval-based forms (or those with a heavy eccentric component such as running or body weight circuits) since these variations place the body under more overall stress and create more muscle damage in comparison to lower intensity variations like walking or slow cycling.

And remember, it’s not just your muscles that are being placed under additional stress either; your joints and central nervous system are also impacted, and they require time and resources in order to properly recover as well.

2) It negatively affects weight training performance.

Aside from the recovery aspect after weight training, performing too much cardio can also affect your actual weight training performance if it’s being done in close proximity to your workouts.

For example, high intensity sprints or a long duration session on a stairstepper could reduce your strength during a leg workout… hitting a heavy bag might impact your performance on an upper body pushing workout… or carrying out an intense rowing session could affect your upper body pulling strength.

These are just a few examples of many.

And if you’re doing things like body weight circuits, kettlebell workouts or barbell complexes as forms of cardio, these will stress your entire body as a whole and can easily drain some of your strength and energy for an upcoming weight training session.

The most important principle when it comes to building muscle optimally is to strive for progressive overload and continuously add more weight to your lifts over time, and that’s why it’s crucial that you always enter the gym fresh and fully prepared to train at your maximum potential.

3) It burns additional calories.

This can obviously be beneficial if your goal is to lose fat, and it can also be helpful during a bulking phase for those with larger appetites who want to keep their body fat gains under control.

However, very large amounts of cardio that burn through a high number of total calories throughout the week can become a real problem if you aren’t properly compensating for it through your diet.

If you want to build muscle and gain strength as effectively as possible, you need to be maintaining a net calorie surplus by taking in more calories than you burn from day to day.

Excessive cardio can significantly reduce the size of your overall calorie surplus or even eliminate it altogether, which in turn will sharply slow down your muscle building progress or even prevent you from making any noticeable gains at all.

How Much Cardio Is Too Much?

cardio and muscle growth

So, now we come to the real question…

What exactly would be considered as “excessive cardio”, and exactly how much cardio is too much?

Keep in mind that there’s no definitive answer here that will apply to every single person across the board, since the style and duration of the cardio you do, your nutrient intake, strength training routine, sleeping habits, external stressors, genetics and overall lifestyle will all affect how much cardio you can safely get away with without impacting your gains.

However, for most average trainees in most situations, 2-3 cardio sessions per week is almost certainly not going to have a negative effect on your muscle building progress as long as your nutrition and sleep are on point, and most people can probably get away with 4 if for some reason they want to perform that much.

I’d consider 4 sessions the upper limit though, and I’d also recommend utilizing a mix of both high intensity (HIIT) and low intensity (LISS) forms of cardio since performing high intensity variations exclusively can easily burn you out when done on top of a complete weight training routine.

You’ll also want to space your cardio out during the week as best you can so that it has minimal interference with weight training performance and recovery.

For example, you ideally wouldn’t want to do hill sprints the day before a heavy leg workout or perform an exhaustive session on a rowing machine in close proximity to a back workout.

So, just make an effort to position your cardio workouts on the specific days of the week that would maximize recovery and prevent training overlap as much as possible.

If you do want to combine weight training and cardio into a single session for convenience sake, always perform your cardio post-workout rather than pre-workout. Weight training should always be given top priority in your program, and you don’t want to negatively impact your strength by pre-fatiguing yourself with a full cardio session prior to hitting the weights.

As long as you’re keeping your weekly cardio sessions within these parameters and have your nutrition and sleep dialed in, the idea that “cardio burns muscle” or leads to muscle loss is not something you’ll need to concern yourself with.

The one caveat I would mention though is that you also need to take into account any other strenuous activities you might be performing during the week, such as a physically demanding job, sports, martial arts, outdoor activities etc.

For example, someone who works in construction, plays soccer twice a week or does kickboxing regularly would not be wise to then go and add 3-4 more cardio sessions on top of that if they’re trying to optimize muscle growth.

Any activity that gets your heart rate elevated and requires sustained physical exertion should be counted towards your cardio total for the week.

Lastly, keep in mind that these guidelines also assume that it’s your goal to fully maximize muscle size and strength gains.

If you’re going for a leaner and more athletic look or if you’re performing cardio simply because you enjoy it or have practical use for it (such as improving conditioning for a sport), then the amount of cardio you perform is really up to you and it doesn’t necessarily have to be limited to 4 times per week.

For example, if you’d prefer to do 5-6 sessions a week with the understanding that it probably will impact your muscle gains to a certain degree, then that’s obviously fine since it totally depends on the preferences of the individual and on what their specific fitness goals are.

The Benefits Of Performing Cardio

does cardio kill gains

Not only is including a few cardio sessions throughout the week “fine” from a muscle building standpoint, but it’s actually something that I’d highly recommend to most trainees for the overall health and fitness benefits it provides.

Aside from the obvious fact that cardio burns calories (helping you to improve fat loss during a cutting phase or potentially reduce body fat gains during a bulking phase), here are a few other less commonly discussed upsides of including a moderate amount of cardio in your plan…

1) Cardio can improve muscle recovery in between workouts.

While excessive amounts of cardio can have the opposite effect by impeding recovery in between weight training sessions, a moderate amount can actually be beneficial in this area.

This is particularly true of lower intensity/steady state cardio sessions, which gently increase blood flow to the muscles in order to remove metabolic waste products that were generated from your workout.

Not only does this lessen the discomfort of delayed onset muscle soreness, but it can actually help your muscles recover more quickly in the days following a weight training workout.

2) Cardio improves insulin sensitivity.

When you become more senstive to insulin, carbohydrates are more likely to be stored as glycogen rather than fat, and you’ll have lower levels of inflammation and require less recovery time in between workouts.

The opposite happens when you’re insulin resistant.

Food is more likely to be stored as fat, recovery between workouts takes longer, your quality of sleep decreases, and you increase your chances of developing a lengthy list of possible health problems.

3) Cardio improves metabolic conditioning.

Aside from your “aesthetic desire” for a big chest and lean abs, let’s not forget about the basic benefits of simply maintaining sound overall cardiovascular conditioning.

If you’re following a typical muscle building style routine that uses low to moderate reps and longer rest periods in between sets, you’re really not getting much in the way of effective cardiovascular work.

A few points to consider on the issue of improving your overall metabolic conditioning…

First, it will have direct carry over to certain exercises that you perform in the gym. For example, having decent cardio conditioning and work capacity will benefit you on big compound lifts when they’re taken into slightly higher rep ranges, as well as helping you recover faster in between sets.

Secondly, if you perform little to no cardio during your bulking phase, it’s going to be a very painful process shifting into regular cardio once you decide to cut. Excessive periods without cardio exercise will cause your overall conditioning to drop very quickly, and you’ll then have to build it right back up from scratch.

Thirdly, poor cardiovascular conditioning will also negatively impact you in regular day to day life. For example, if you’ve been neglecting your cardio altogether and then head out to play a game of basketball with your buddies, it won’t be long before your lungs catch fire and the experience is no longer enjoyable for you.

4) Cardio improves sleep quality.

Weight training has beneficial effects on sleep as well, but if you live a relatively sedentary lifestyle aside from maybe 3-4 hypertrophy style workouts per week, you’re probably still not getting in enough total exercise during the week in order to optimize your sleeping patterns.

Perform a couple cardio sessions in addition to your weight training workouts and you’ll be surprised at the positive effect it can have on helping you fall asleep faster as well as sleeping more deeply throughout the night.

Better sleep quality has positive implications not only for recovering in between workouts and improving gym performance, but also for boosting your overall energy and focus in regular day to day life.

Aside from the benefits that cardio produces on basic muscle growth, fat loss and cardiovascular conditioning, but here are a few other positive effects of cardio to keep in mind when it comes to your physical and mental health…

  • Cardio improves cognitive function. One of the key ways cardio enhances brain health is by raising levels of “brain-derived neurotrophic factor” (BDNF), which is a protein vital for the growth of your neurons. Not only does performing cardio over the long term produce a cumulative benefit on your mental performance, but it can also give you an immediate boost as well in the hours following a cardio session.
  • Cardio improves mood and reduces the effects of anxiety and depression. It does so by regulating serotonin and norepinephrine levels, two key “feel good” neurotransmitters in the brain. In fact, studies have shown that aerobic exercise can be just as effective as medication for treating mild/moderate depression.
  • Cardio can decrease your risk of almost every modern disease. This is true of exercise in general, but again, if you’re relatively inactive outside of weight training, including some extra cardio can help to reduce your risk of developing many health problems such as heart disease, osteoporosis, diabetes, asthma, cognitive diseases like Parkinson’s and Alzheimer’s, and even various forms of cancer.
Does Cardio Burn Muscle And Kill Gains? The Bottom Line

is cardio bad

So, does cardio “burn muscle” and “kill gains”? Is cardio “good” or “bad”?

As long as you keep it within moderation (2-3 sessions per week using a mix of HIIT/LISS will be the “sweet spot” for most average trainees) and space your cardio out intelligently during the week in order to maximize recovery, not only will cardio NOT negatively impact your gains, but it will also produce a wide variety of valuable overall health and fitness benefits.

So, if you’re like so many people out there who are relatively inactive outside of weight training, I’d highly recommend getting in at least a couple cardio sessions in during the week.

Our bodies evolved to move, and being stationary throughout most of the day is not natural to our physiology.

Some people will say that weight training alone produces the same benefits and therefore cardio is unnecessary, but if you simply compare the physical and mental impact of a typical hypertrophy style workout versus an actual full-on cardio session, there’s no question that these two types of exercise affect the body differently.

Even if you aren’t using cardio as a means of improving body composition, the psychological benefits alone are well worth it.

When you’re more physically active throughout the week you’ll just simply feel better, and this will have direct positive carryover to all areas of your life from your fitness program to your work to your social life and more.

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