Aerobic exercises are basically focused on repeated body movements which help to increase your pulse and keep it elevated for a longer period of time. Don’t be under the misconception that aerobics just involves jogging though. There are a variety of different types of aerobics including interval training, circuit training, etc.
As far as your body is concerned, there is an order in which energy is used. The first thing that your body will use is the carbs from all the food you eat. This is basically instant fuel for your body. After this, your body will start using fat which comes from the food you eat and is also stored in your body. And after both these sources are exhausted, it will start using the proteins & amino acids in your muscle tissue.
Now, I’m sure you will understand that aerobics does indeed start to reduce your muscles eventually. At this point, your body will be in a catabolic state where both primary sources of fuel have already been utilized for maintaining proper cardiovascular performance. And after this, it is only obvious that your muscles will be the next source of energy.
You will obviously want to know the point at which your body will run out of primary energy sources and start using your muscles. The general belief is that if you do cardio for more than an hour, you will start burning away muscle tissue. That’s why you should never do cardio for more than 60 minutes max.
But what about if you play a sport which stretches for longer than one hour? You wouldn’t want to lose muscle now would you? In this case, it is recommended that you have a healthy meal filled with fat, carbs and proteins two to three hours before you start working out. This will give your body sufficient fuel during your workout.
You should also consider having isotonic sports drinks during your workout to help fuel your body and spare any muscle loss whatsoever.
Let me tell you one more thing. If you are trying to build your muscles, don’t engage in cardio or any form of running for more than half an hour so that you save up enough energy for your weight training. If you spend all your energy in cardio, how will you exert your muscles and build them?
So now that you know the advantages and disadvantages of running, plan your workouts accordingly. Depending on your goal, determine how long you need to run for. But no matter what you do, don’t skip cardio as it is very important in order for you to maintain a healthy body and remain fit.