Does Cardio Burn Muscle Mass Or Fat? Don’t Be Scared Of Doing Cardio!
I’ve been asked a few times now if I’m worried about losing muscle from doing cardio. To be honest, I’m really not. Yes, you can burn muscle from doing too much cardio, but you can also not burn muscle. It really just depends on how much you do and how you do it. So in reality, the answer is no, cardio does not burn muscle; training in an incorrect way is what burns muscle.
After documenting my results of doing eight straight weeks of consistent cardio training on http:visualimpactcardioreview.net, I’ve been asked many different questions regarding muscle loss vs. fat loss. My overall reply is that I’m usually not too concerned because I don’t over-train or under-eat. In this article, I want to go into a little more detail.
Since this post isn’t about the benefits of cardio I won’t go into detail on that, but I am a fan of cardio. I feel that it is a good way for those of us who have desk jobs or are stationary for the majority of the day to get in some quality exercise. Lifting weights is good, don’t get me wrong, but getting your heart rate up, sweating a bit and doing some good ole’ cardio is good too. I personally don’t fall into the crowd who thinks cardio is dead. It may not be necessary to get in shape, but it certainly isn’t ineffective either.
When Does & Doesn’t Cardio Burn Muscle?
There are many different types of cardio. Some cardio is considered better for burning fat, some for increasing your lactate threshold and there is even some cardio designed for burning muscle. Overall, cardio can be a very powerful tool when used correctly. The so-called phenomenon around cardio burning muscle is more of a result of poor diet and/or over training than the type of exercise itself.
There are three situations where your body will burn muscle:
- Muscle is the only source of energy available
- You are not consuming enough protein
- Over training
Believe it or not, these shouldn’t be taking place too often. Whenever you exercise (or do any type of physical activity) your body has a pattern it follows. First, you burn carbs, then you burn fat and THEN you burn protein, which is what causes muscle loss. So it’s not the cardio that burns muscle, it’s the lack of proper diet and/or rest that burns muscle.
Where’s the proof?
There are quite a few studies that show muscle loss is a result of poor nutrition, extreme circumstances and just downright improper training. In addition to these, there are many that prove cardio to be very effective at burning fat, not muscle.
Take for example a study that was done back in 2009. In an in-depth evaluation of 22 runners, there were 15-17 exams done on each runner that proved the effectiveness that endurance running had on fat loss. In this study, the runners were tracked as they ran 2,500 kilometers (just over 2,796 miles) from April 19 to June 21, 2009. The results of the study …
“… showed that runners lost an average of 5.4 percent body volume … most of which was in the first 2,000 kilometers … Loss of muscle volume in the leg averaged 7 percent.”
You might be thinking, “but hey, that says right there that they lost 7 percent of their muscle.” Well, not quite. There are a few things we need to look at.
First, they lost ZERO muscle from their upper body. Again, these runners lost no muscle from their arms, shoulders, back, chest etc. What these runners did experience was muscle loss in their legs only. Why? Because they were over training.
So you can see why looking at a study like this and then saying cardio burns muscle would be crazy. Yes, if you run 43 miles everyday for almost two months, yeah, you’re going to lose a bit of muscle! But, does cardio burn muscle? No, it’s not cardio that’s burning muscle.
Unfortunately though, there are many who bash cardio for one reason or the other. Some feel it isn’t a cool enough form of exercise while others may feel that it is simply a waste of time. Don’t fall into that trap.
Cardio is a great form of exercise and it’s actually good for you. Not only does it NOT burn muscle, it aids in the muscle building process. That’s right, cardio actually helps you build muscle. Cardio can increase circulation to the muscle and that will increase the amount of nutrients as well as the time it takes for these nutrients to get to your muscles.
As long as you get enough protein … maybe not even as much as you think you need, do some sort of strength training and don’t run 43 miles everyday for two months you really don’t need to worry about cardio burning muscle.
Keith Lai
May 8, 2012 @ 1:59 pm
Good job busting some cardio myths Kevin. Honestly wasn’t too familiar that cardio can build muscle. Very interesting…
Kevin
June 1, 2012 @ 7:31 am
Thanks Keith … yeah, not quite a “muscle building” exercise, but it certainly doesn’t prevent or hurt muscle building.
George Super Boot Camps
May 9, 2012 @ 7:02 am
I think that whilst the average Joe needs to stop being afraid of doing cardio when aiming for a good looking body, the post here needs a little clarification. I don’t say this to be particularly confrontational, I just want to expand things a little.
With respect to cardio helping in the building of muscle, whilst I can accept that extra nutrient delivery could make a difference to how well nourished a muscle is, I also see a problem with excess stress, and confusing the body as to what you want it to do.
Exercise is a form of stress, and when you want your body to put on new muscle, you want to apply the type of stress that will lead to an increase in muscle. This, as we all know, is weight training, or resistance training. When you apply the stress of cardio, even on a background of a greater stressor of resistance training, you dilute the hypertrophic effect of weight training.
The study you quoted above is slightly off in this regard because it looked at muscle loss in people who are not interested in preserving or increasing muscle mass. I have no doubt that had these participants done some resistance training they would even have put on some muscle. But would it have been optimal? No chance.
I also think that people who would be labelled as ‘hard gainers’ would be well advised to stay away from all but the lightest cardio, and only the occasional HIIT, just for the benefit of keeping oxygen delivery ability high.
I totally stand with you on the protein front though; if you are going to do cardio, you might want to take steps to ensure that you do it with some amino acids floating around your bloodstream sot that your liver feels no need to start catabolising your won muscles!
Just my 2c,
Keep up the good work,
George
(ps in the last sentence of the penultimate paragraph you might want to add the word decrease, so that it doesn’t read like an increase in time will also occur…)
Angie
May 9, 2012 @ 8:46 am
Just had my home gym built by Backyard Rooms. Thanks for clarifying the myths on cardio, I was hesitant to order a treadmill for fear it would just take up space.
I was also unaware that cardio builds muscle.
Angie
Kevin
October 12, 2012 @ 5:51 pm
You bet! … Not really a “muscle building” exercise, but good for the body and that can help build muscle.
Dave - Not Your Average Fitness Tips
May 16, 2012 @ 12:18 pm
I’m a big fan of cardio myself although the loss of muscle is always in the back of my head. As I worked through the advanced VI cardio routine, I did scale back a few times because I felt like my legs were too exhausted to do some of those lactate threshold intervals in the last few weeks. I figure if I’m getting enough protein and doing strength training, then muscle loss shouldn’t be a huge concern.
Kevin
June 1, 2012 @ 7:32 am
Yep – I hear ya, it’s drilled into our heads that we’re going to lose muscle, but after giving it a shot you can see that it’s simply not true.
Alvaro L.
May 24, 2012 @ 7:34 am
I regularly lift weights 4x per week and run an average of 25-30 miles per week on trail and asphalt. So far, I have lost absolutely no muscle and the results with regards to my overall fitness have been outstanding. I have gotten leaner, stronger and can work harder at the gym, since I have more cardiovascular endurance. I think that “looking good” is important and you can achieve that with zero cardio, but the benefits of cardio to your overall physique and health are amazing. Therefore, I always recommend to at least do 15-30mins of cardio after their strength training routine. In order to lose muscle with cardio you would have to eat very poorly and/or do massive amounts of cardio, which the normal person never does.
Kevin
June 1, 2012 @ 7:33 am
All true and well said!
nieves
May 24, 2012 @ 8:59 am
Truth is, my body changed for the worst when I was no longer able to run regularly (3-4 miles x 4 a week) due to a knee injury. I know I have a lot of muscle from regular weight training and cardio, I weight a lot for my size (130#, 5’1, 27-28 jeans) but all is covered in an inch of “blubber” that I can’t get rid of hard as I try.
Kevin
June 1, 2012 @ 7:35 am
Nieves,
I’ve got a bum knee too. For my cardio workouts I use the bike for anything with high intensity and the elliptical for low intensity … hopefully you can do at least these?
nieves
June 1, 2012 @ 9:41 am
Thanks for the reply, Kevin. Yes, I do two variations of elliptical and it works fairly well, but the bike, much as I know it helps bores me to death! I try to bike to work (7 miles round trip) whenever i can, but don’t count it as cardio. Running kept me lean, though, and the other workouts not as much…
paul
May 24, 2012 @ 9:23 pm
Kevin,
Your results speak for themselves really. I think one place where cardio can be a problem is where the cardio exercise (if done intensely or excessively) can interfere with recovery times, especially if you goal is strength gains in the legs and you program cardio around leg traininig without allowing time for recovery. Where I think it can be advantageous is when you want to run a deficit, calorie wise, and yet you want to ensure you get you RDI of micros. Easier to get RDI at maintenance than 500 cals belo. Great achievement. Good luck maintaining the results now that you did th hard work to get there. Cheers Paul
Kevin
June 1, 2012 @ 7:35 am
Paul – agreed! Cardio does have it’s place and time.
Dave
June 8, 2012 @ 3:35 pm
Should I do cardio before or after weight training?
Kevin
June 11, 2012 @ 1:27 pm
I’ve heard a few different opinions, but I personally feel that it’s much better to do cardio after you lift weights … I should put together an article on this 🙂
One of the main reasons I like cardio afterwards is that you are able to lift heavy because you have all of your energy. Another plus is that after weight training much of your glycogen is depleted so the cardio will end up burning more fat.
javier
July 1, 2012 @ 6:44 am
Great article, i agree. I’m a runner, i run about 22 – 27 miles every week. I’m pretty thin, & i have not lose any muscle at all. My whole body got toner, stamina, & endurance. I hated when people say you should lift weights instead of cardio. I believe strength training is good, but i think cardio is better for the heart.
Kevin
October 12, 2012 @ 5:53 pm
Thanks for the comment Javier!
Danny
August 11, 2012 @ 6:52 am
Hi Kevin, I’m looking to lose some muscle.
I watch what I eat so I don’t have much fat but my arms are
bigger than I’d like, just want to look slimmer. How would you
go about losing muscle from your arms in a healthy way?
Appreciate any advice you could give me.
Sanchito
September 2, 2012 @ 10:24 pm
hey Kevin
Got a question: Instead of doing cardio like just running, is doing cardio in the form of an AMRAP (as many rounds/reps as possible) for example as cardio I sometimes do 20 minute AMRAP of burpees, or 30 minutes of Burpees + push ups + bodyweight squats .. is that also an acceptable form of cardio?
thanks Kevin
Kevin
October 12, 2012 @ 5:56 pm
It really depends on what you’re training for. That will build endurance but not much strength and not muscle gain.