Is it true that aerobic exercise loses muscle mass?

Aerobic exercise itself will not necessarily lead to muscle loss. Only when there is a problem with your training and diet, and the core prerequisites of "long-term high intensity, no strength stimulation, and insufficient protein intake" are met, muscle loss may occur.

When I was in my third year of fitness, I was in a hurry to gain body fat in order to catch up with my summer trip to the beach. The stupidest pitfall I ever encountered was that I used aerobics as a fat-removing miracle drug. I climbed stairs for an hour on an empty stomach every morning, and ran another 5 kilometers after get off work in the evening. I originally cut my strength training from 5 times a week to only 2 times, and I only ate protein every day when I thought about it. An egg, but within two weeks I realized something was wrong: my deadlift weight dropped by 10kg, and my arm circumference shrank by almost 1cm. At that time, I also followed the opinions on the Internet and criticized aerobics as a muscle killer. It was not until I talked to the old coach of the team that I realized that this was purely because I was pushing my muscles to a dead end, and it had nothing to do with aerobics.

In fact, the fitness circle has been arguing about this issue for almost ten years, and the two schools of thought still have their own supporters: Most of the old-school bodybuilding seniors avoid aerobics. In their early years, they basically relied on carbon control to prepare for fat-burning competitions, and almost did not touch aerobics, for fear that the hard-earned muscles would be consumed. This kind of thinking has indeed helped many people get results, so many old coaches still tell novices to do less aerobics. But in recent years, more and more natural fitness players have added aerobics to their competition preparation plans. Several of my bodybuilding friends even do steady-state aerobics 4 times a week during the preparation period. Body fat loss is stable, the muscle retention rate is much higher than during the pure carbon control period, and post-game recovery is faster.

To put it bluntly, whether you will lose muscle depends on whether the "input" you give to the muscles can withstand the "output". Let me give an analogy, you regard muscles as employees you pay for. You usually neither pay wages to people (the protein intake cannot keep up, and cannot even meet the basic amount of 1.2g per kilogram of body weight), nor assign growth tasks to people (no strength training at all, and do not give the muscles enough resistance stimulation). You also force people to work continuously every day (a single aerobic session exceeds 90 minutes, or aerobic time exceeds 150 minutes a week without replenishing enough calories). If you were an employee, wouldn't you run away?

Here we need to clarify a common sense for everyone: when we do low- to medium-intensity aerobics, glycogen and fat are the main sources of energy for the first 40 minutes or so. Only when glycogen is depleted and you fail to replenish energy in time, the body will activate the gluconeogenesis mechanism - simply put, it breaks down the protein in the muscles and converts it into energy for your use. Ordinary people usually run for 30 minutes and dance for 20 minutes. The glycogen is not used up at all. How can they tear down muscles?

Many people say that they think they have lost muscle when their leg circumference becomes smaller after running for two weeks. This is really a big misunderstanding. Most of what you lose is water and fat. How can muscles be lost so easily? You have worked so hard for three months to gain 1kg of pure muscle, but you can lose it in two weeks? Then fitness is too easy.

If you are really afraid of losing muscle during aerobic exercise, I will give you a reference based on my own experience during the fat-burning period: first control the duration of aerobic exercise, and do not exceed 50 minutes in a single session. Arranging 3-4 times a week is enough. Priority is given to joint-friendly medium and low-intensity aerobic exercise such as brisk walking, elliptical machines, and swimming. If you really like high-intensity intervals, do it up to 2 times a week, and don’t do it every day. Don't cut it when it comes to strength training. Just do it how you want to do it. If you give your muscles enough stimulation, your body will know "this thing is useful and can't be thrown away." The most important thing is to eat enough protein. During the fat brushing period, you should eat 1.6-2g per kilogram of body weight. Don’t open the calorie gap too much. At most, 300 calories less than the basal metabolism is enough. I followed this method last time I brushed fat. I lost 3% of body fat in two months, and my bench press increased by 2.5kg. I didn’t lose any muscle at all.

Oh, by the way, there is also the fasting aerobics that everyone asks about the most. It is really not that scary. You drink a spoonful of protein powder or eat an egg white before you get up, and control it within 30 minutes. Many players around me do this during the preparation period, and the muscles are not so fragile.

You really don’t need to treat aerobic as a scourge. You don’t have to reach a body fat below 5% for a career. Ordinary people do aerobic for 30 to 40 minutes three or four times a week. It can not only improve cardiopulmonary function, but also help control weight. As long as you don’t do extreme operations, you won’t hit the threshold of losing muscle. Don’t scare yourself by listening to the extreme comments on the Internet.

After all, the ultimate goal of our fitness is to be healthier. We can't even dare to do aerobic exercise that is good for our heart and lungs just for the sake of those muscles, right?