Muscle proteins are broken down and used for energy during aerobic exercise. But your body is constantly breaking down muscle tissue, so there is nothing to worry about, this is called protein turnover. The thing that you should strive for is to have more anabolic so you can gain and maintain muscle. But let’s not forget that it is possible for you to lose muscle from doing too much cardio – even though it is unlikely. It’s hard to say what constitutes too much cardio, so it just safe to assume that you can do about 45-60 minutes of cardio a day without losing any muscle. John Parillo the trainer said that, “Aerobics can enhance your recovery from weight training by promoting blood flow and oxygen transport to your muscles.” It also forces oxygen through your body, increasing the number and size of your blood vessels. Blood vessels are the supply routes that transport oxygen and nutrients to body tissues, including muscles, and carry waste products away for muscular growth, repair and recovery. The expansion of this circulatory network is called cardiovascular density.
When it comes to losing muscle it has to do with an inadequate diet than with excessive aerobics. So if you think that you are losing muscle, it is from either one of these four causes:
The first one is that you are not eating enough protein. That is the only protein that is used to build muscle, so it you want to keep your anabolic up you should eat up to 5-6 meals that contain protein. And the best way to spread out these meals is abut 3 hours apart.
The second thing is that your carbs are too low and a low carb diets are usually used for fat loss.
The third factor is that you’re not eating enough calories to support muscle growth, and this is the most common cause of muscle loss. The fact that your muscles are to low your body goes into starvation mode which means that you metabolism slows down and your body actually burns muscle tissue to conserve energy.
Lastly, you probably are not using weights. Some people think that not using weights and just doing cardio will help with weight loss but rather it is the thing that helps keep your muscles while you are dieting.
So to sum it all up, you are more likely to lose muscle from not eating enough. Because people feel that if they starve themselves that the fat will be the only thing that happens is the complete opposite. The only way to maintain lean mass while dieting is to feed your muscles with plenty of calories and at the same time. No matter what your goal is when training you should always include cardio and don’t worry aerobics DO NOT cause muscle loss. The reality of it is that it supports muscle development.