Many folks tend to think that any type of cardio exercise will burn muscle and many body builders avoid doing cardio because they are afraid of losing their lean muscle mass on gaining which they worked so hard. In this article I'll try to address this common question asked by many beginner bodybuilders and weight lifters: Does cardio burn muscle?

At any time of the day or night your body uses a combination of carbohydrates, fat and protein to fuel your body with the energy it needs just to stay alive. Exactly the same happens when you train – your body burns these three types of fuel to cover your elevated energy expenditure. However, the higher intensity of your physical activity, the higher contribution of carbohydrates to energy production and the percentage of fat and protein being burned decreases proportionally.

Cardio Doesn't Burn Muscle

It has been scientifically proven, that during high intense workouts your body takes the majority of its fuel from carbohydrates and only little energy from fat. And protein is used in even smaller amounts to produce energy. Usually the contribution of protein as an energy source is only 10% of the total energy expended during low intensity workouts and as little as 2% during high intensity workouts.

This brings us to the conclusion that it's virtually impossible to burn muscle during cardio training, because your body will use mainly carbs and fat and next to no protein for energy production. Moreover, your muscles are made from protein that is already built into your body in the form of a muscle tissue and it would be extremely difficult for your body to disintegrate this already built-in protein and make it reusable for other purposes. Therefore, your body will only burn muscle when it is forced to and it has absolutely no other source of energy it could use. This can happen, for example, when you've been starving for a very long time and all of your body fat is gone.

And of course, this can happen if you're on a drastic diet too. Cardio exercises have gotten a bad reputation and have been blamed for burning muscle mass because they are often combined with drastic fat loss diets that are very low in fat and carbohydrates which are main sources of energy. And as mentioned before, if you don't eat enough food, i.e. carbohydrates and fat, to cover your energy expenditure your body will eventually be forced to burn muscle. So it's not cardio to be blamed for muscle loss, but the lack of proper nutrition – by eating too little food you will literally cannibalize your muscles!

Bodybuilders CAN Benefit From Cardio

Now I have addressed your concern over burning muscle by doing cardio, I will explain to you how you can capitalize on introducing cardio exercises into your workout plan.

Generally speaking, cardio exercises, within reason, are beneficial to your health. They keep your cardiovascular system in good shape, which is absolutely essential if you're serious about lifting weights or bodybuilding.

Another important benefit from cardio is that it helps tackling muscle soreness after working out. Hanging out on the couch seems like a good idea if there's soreness following a hard session, a low-intensity cardio such as jogging or easy aerobic will help relieve the pain. It is so, because faster blood circulation means faster delivery of nutrients to your muscle cells and helps them rebuild more quickly.

Summary

To sum it up, cardio can be beneficial to you as a bodybuilder if applied within reason and accompanied by proper nutrition. It will not burn muscle unless you're on a hardcore diet or starving.