The cardio workout itself is a useful activity.
Without the right balance between workouts, nutrition, and recovery (according to the individual goals), however, this activity can cost you your muscles.
Yes, the loss of muscle mass because of cardio activities is possible under different conditions.
Cardio workout – duration
If we want to have a relatively low percentage of body fat, we need to find the right balance between training (the cardio element) and nutrition.
Unfortunately, there is still the myth that the longer the cardio session is, the more fat will be burned.
Actually practicing cardio to exhaustion for an hour or even two will not only not make you lose fat, but will bring your body to a catabolic mode and as a result, you will 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?
There is no specific formula to calculate that.
Everything is strictly individual and depends not only on the physical characteristics of the athlete but also for specific purposes.
If your cardio workout is with low and monotonous intensity and its duration is insufficient, it may not be really effective.
If it is too long, on the other side, it could lead to loss of muscle mass.
Everything over 60-70 minutes a day is unproductive, especially if not accompanied by enough protein and calories in general.
The optimal option is 30-40 minutes. It is true that one should think in the gym.
Unless you are a long-distance marathon runner, long cardio can take you back a few steps.
Something that you should pay special attention to – the intensity of the cardio session is more important than its duration.
What should be the intensity of the cardio workout?
The pulse that you maintain during your workout is of great importance.
The appropriate intensity is calculated as a target value and as a percentage of the maximum pulse (which is based on the formula: “220 minus the age of the athlete”).
It is good, especially for the more trained people, to maintain 60-75% of the maximum pulse.
How to combine the duration of the cardio session with its intensity so that the risk of muscle loss is minimized?
There are several ways to replace the endless hours on the treadmill with shorter but more effective activities.
- Tabata protocol workouts;
- Workouts that combine a strength activity and a cardio activity after it;
- High-intensity interval workout.
The frequency of your cardio workout
You may not be one of those people who run on the treadmill for two hours, but on the other hand, you have too much cardio activity in your exercise mode – another condition to start losing muscle mass.
This is especially true for people who love cardio and who try to avoid any kind of workout that can load, develop, and protect their muscles (strength training – own bodyweight workouts or training with weights, resistance training, etc.).
There are different options; everything depends on you and your goals.
If the cardio is more than 3-4 times a week, it can be combined with strength training and can be continued afterward. Let its duration be less (try different HIIT versions).
Another option is to alternate a day when you have only a strength training session with a day when you only have cardio activity.
Listen to your body and remember that “more” does not mean “better.”
How to eat properly
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 your protein intake is not sufficient (as proteins are the building blocks of the muscles.)
If you have the right amount of proteins, but you have minimized the energy sources, your body first uses carbohydrates and fats, and besides that, you have an NCB (negative calorie balance).
Then your body will have no choice but to process the proteins and the available muscle mass for energy.
If the ratio of carbohydrates, proteins, and fats is good, but the overall calories are too low.
Too long cardio, no/not sufficient carbohydrates in the food for muscle glycogen synthesis.
These conditions, combined with a lot of cardio (and in physical activities in general) will bring you only downsides.
A cardio workout on an empty stomach
The issue of cardio on an empty stomach (in the morning after sleep) is very controversial.
The most widely accepted theory is that this is the most effective option for burning fat because the blood glucose and glycogen content of the muscles are the lowest at this time of the day.
At night the muscles use mainly fat as energy to keep the glucose in the brain.
During fasting, the fat burning process is intensified. The other theory, of course, is radically the opposite.
It is true that cardio on an empty stomach may increase the use of body fat for energy much more than cardio in a fed state (except for cardio with too low intensity, even on an empty stomach).
The morning cardio on an empty stomach can have a catabolic effect on the muscles.
Studies have shown that working out with depleted glycogen significantly increases the amount of protein tissue burned for energy during exercise.
This protein loss may be more than 10% greater than the total calories burned during the cardio session on an empty stomach – twice as much as after a meal.
If cardio on an empty stomach is really risky for the muscle mass, what should we eat before exercise to preserve our muscles and burn mainly fat?
This depends on the frequency, the intensity, the time elapsed from the meals before the cardio session, the individual genetic features.
There is one rule: ¼ grams of carbohydrates and 1/8 grams of proteins from your ideal weight in pounds (1 pound = 0.453 kg), which may be different from your actual weight).
The intake of branched-chain amino acids as a dietary supplement before and during cardio eliminates the dilemma.
Cardio, combined with other factors, can surely cause muscle mass loss.
If you do not want this to happen, carefully analyze your exercise and diet by keeping a diary.
There is no exact formula, nor a 100-percent truth, especially with regards to the human organism.
We are not strictly set computerized machines.
Countless factors are affecting our condition.
However, pay attention to whether you are recovering well (food, sleep, supplementation), whether your workout is too exhausting (anyone can learn to listen to their body and recognize the symptoms of overtraining) and whether you have found your personal balance.
Refer to the fitness and nutrition articles in the edition if you need more information (what is cardio, how to know the symptoms of overtraining, how to calculate a sample calorie balance, or what diet and exercise regime to choose according to our individual features and goals).
Work out with pleasure!