Loss of muscle mass in cardio activity

The cardio training itself is a useful activity. Not the right balance between workouts, nutrition, and recovery (based on personal goals) is found, but with this activity, you can sacrifice part of your muscles. Yes, the loss of muscle mass through cardio activities is possible under different conditions.


If we want to have a relatively low percentage of body fat, we need to find the right balance between training (in which the cardio element is involved) and nutrition.

Unfortunately, the myth still spreads that the longer the cardio session is, the more fat will be burned.

In fact, practicing cardio to exhaustion, for an hour or even two, not only will not melt your fat but will lead your body to catabolic mode, which will cause you to start losing your muscle mass. This loss contributes to the slowdown in metabolism. In other words, burning fat will become a difficult task.

How much cardio is too much cardio?

There is no specific formula on which to calculate. Everything is strictly individual and depends not only on the physical characteristics of the athlete but also for his specific purposes.

If your cardio workout is low, monotonous, and inadequate, it will not be as effective and, if it is too long, would result in muscle loss.

Everything over 60-70 minutes a day is unproductive, especially if not enough protein and calories in general. The optimal option is 30-40 minutes.

The fairytale is that the room should be thought of. Unless you are a long-distance marathon or runner, long cardio can take you a few steps back. Something you should pay special attention to - more important than the duration of cardio is its intensity.

What is the intensity?

Of great importance is the pulse that you maintain during your workout.Appropriate intensity is calculated as a target value as a percentage of the maximum pulse. It is good, especially for the more advanced, to maintain 60-75% of the maximum heart rate.

How do we combine the duration of the cardio session with its intensity so that the risk of losing muscle mass is minimized?

There are several options to replace endless hours on the path with shorter but more efficient activities.

• Training that combine strength and cardio activity after it.

High-intensity interval training.


You may not be one of those who takes the trail for two hours but, on the other hand, have too much cardio activity in the exercise regimen - another condition for losing muscle mass.

This is especially true for cardiologists who avoid any kind of workouts that load, develop and protect muscles (strength training - weight or weight, resistance training, etc.). There are different options, again everything depends on you and your goals.

If cardio is more than 3-4 times a week, it can be combined with strength training and practiced afterward. Let its duration be less (try different HIIT variants).

Another option is to alternate a day when you have only a strength training session with a day when only cardio activity is present.

Listen to your body and remember that "more" does not mean "better."


The inadequate ratio between eating and training can also lead to muscle loss:

• If you have found the balance between calories taken and consumed but you do not have enough protein intake that is a muscle building block.

• If you have the right amount of protein, but you have minimized the energy sources the body uses first - carbohydrates and fats, and in combination with that you are in the CST. Then your body will have no choice but to process the protein for energy and the available muscle mass.

• If the ratio of carbohydrates, proteins, and fats is good, but the overall calorie intake is too low.

• Too long cardio, no / deficient carbohydrates in the muscle glycogen synthesis diet.

These conditions, combined with a lot of cardio (and in general with physical activities) will bring you only minuses.

Fasting cardio

The issue of fasting cardio (morning after sleep) is very controversial. The most widely used theory is that it is the most effective option for burning fats because the blood glucose and glycogen content of the muscles are lowest for the day. At night, muscles used mainly fat as energy to keep glucose in the brain. Fasting in the fast-sting process increases the fat burning process.

The other theory, of course, is radically the opposite. It is true that fasting cardiotoxin may increase the use of body fat for energy much more than cardio in a fed state (except for too low-intensity cardio, even on fasting). Morning cardio on an empty stomach can have a catabolic effect on the muscles.

Studies show that exhausted glycogen training significantly increases the amount of protein tissue that is burned for energy during exercise. This protein loss can be over 10% greater than the total calories burned during the fasting cardio session - twice as much as after a meal.

Then, if fasting cardio is really risky for muscle mass, what to eat before exercise so as to preserve muscle and burn mainly fat? This depends on the frequency, intensity, time elapsed from pre-cardio nutrition, individual genetic features.

There is one rule: ¼ grams of carbohydrates and 1/8 grams of protein than your ideal weight in pounds (1 pound = 0.453 kg), which may be different from your actual weight).

The use of BCAAs as a dietary supplement before and during cardio eliminates the dilemma.

In conclusion

• There is no exact formula or 100 percent truth, especially with regard to the human organism.

• We are not computerized machines where everything is strictly set.

• Numerous factors influence our condition.

However, pay attention to whether you are well recovering (food, sleep, supplementation), whether your workouts are too exhausting (anyone can learn to listen to your body and recognize the symptoms of over-training) and whether you have found a balance to works personally for you.