Which sports are holding back your growth?

Muscle loss through endurance training? How much is too much

Many strength athletes believe that endurance training leads to muscle loss.

We know that daily cardio training is good for our health. What about endurance training and muscle building?

In this article, you will learn why the statement "endurance training leads to muscle loss" is wrong.

I even go one step further and propose the following thesis: Your ability to build muscle will be achieved through endurance sports Not lowered.

You can even do endurance sports help, Muscle mass build up.

The main reason behind the muscle loss myth is this: Most people associate endurance training with “losing weight” and “losing fat”.

In bodybuilding, a “mass building” phase is often followed by a “definition phase” in which the body fat percentage is to be reduced without losing muscle.

Endurance training is often used as a means to an end in fat loss.

In marathon fitness Stay tuned-Newsletter we have already dealt intensively with the subject of “fat loss”.

And we know that fat loss only takes place when your calorie balance is negative, i.e. when you are consuming less energy than you are using.

The same principle applies to muscle loss: if you do not supply the energy you have consumed with food, you risk losing muscle mass.

So it is not endurance training that is responsible for muscle loss, but too low an energy intake!

What Really Leads to Muscle Loss?

Let's remember: Protein is the essential building material for your body.

You need a constant and sufficient supply of protein (e.g. from eggs) to repair, maintain and build up muscles, tissues and the immune system.

If you don't get enough protein and energy, your body cannibalizes its muscles.

A good rule of thumb for effective fat loss is a calorie deficit of no more than 20% below your daily calorie requirement.

To calculate the optimal energy intake for you, you can use my calorie calculator or one of the formulas presented here.

Proper nutrition is essential to ensure that you do not lose muscle while dieting.

Of course, you can also lose weight with a strange fast food diet.

Then you should also read the “package insert” on risks and side effects: the chances are “good that you will lose valuable muscles with the kilos.

Endurance training does not lead to muscle loss per se.

How can it help you build muscle?

How endurance sports can help build muscle

I can think of three good reasons how you can increase muscle growth through endurance sports - provided you eat enough.

  1. You regenerate faster: Muscle soreness is a common companion that can occur about 1-2 days after high-intensity strength training. 20-30 minutes of endurance training per day improves blood circulation and thus the supply of nutrients to your muscles - this shortens your regeneration cycle.
  2. Maximum muscle building in minimum time: Not all of us want to take a 5-minute break between workout sets. When I do strength training, I want to achieve as much as possible and invest as little time as necessary. Short breaks, complex exercises - I rarely spend more than 30-60 minutes on the equipment. In order to stimulate growth, your training should be intense - and this high intensity takes place in the anaerobic area. So your cycle is always in full swing. You can only do this for 30-60 minutes if you have good endurance. If not, you will not be able to generate the necessary intensity in training to trigger muscle growth. Unless you allow yourself the said 5 minute break between sets.
  3. Muscle multitasking: Muscle building Training plans that combine many complex exercises with short breaks (e.g. circuit or superset training) are potent fitness hermaphrodites. With these types of training you can - provided you have the necessary stamina - work on muscle building and endurance at the same time up to a certain point.

Conclusion: Endurance training does not lead to muscle loss. You lose muscles through crash diets and poor nutrition! 30-40 minutes of endurance training per day are not only good for your health, they also have a positive effect on your muscle growth.

Muscle Breakdown Mechanisms: How To Avoid Them

Let's take a closer look at two situations in which our body burns muscles - then we can avoid them in the future:

  1. Hardgainer: If you are one of those athletes who already have an extremely low body fat percentage (<8%), you should be careful not to run into too great an energy deficit. Since the fat stores are largely empty, your body would then increasingly burn muscles for energy in order to keep you alive.
    Few of us have such a low body fat percentage, we often call them “hard gainers”. To put it bluntly, hardgainers can eat gallons of Haagen-Dasz ice cream without gaining a gram of fat. Delivering the necessary energy for muscle growth is… hard. If you belong to this group, FIRST of all you should be careful with the endurance training - you already have a hard enough time getting enough calories. (You can find the best strategies for hard gainers here.) And Secondly I want you to leave this website immediately with your pack of Haagen-Dasz. Yes i'm jealous!
  2. Protein deficiency: If you don't get enough protein, your body will lose muscle. This often happens in crash diets. "Essential Amino Acids" are called for a reason essential: Your body cannot produce it, it only gets it from the food it consumes. If you withhold them from him, he gets these amino acids from your muscles - by burning them. Another great way to curb muscle breakdown is with BCAAs.
    Rule of thumb: If you reduce your caloric intake by more than 20% below your daily needs, it will be difficult to get enough essential amino acids from your diet. Even if you don't do strength training, your body needs these protein building blocks permanently to renew muscle cells. If protein is not available, cells cannot be renewed. And if you do endurance training in addition to a crash diet, you will even accelerate muscle loss.
    Solution:No Crash diets! Crash diets are counterproductive! If you want to know how many calories you have to take in at least, you can use my calorie calculator or formulas to calculate an estimated value for your daily calorie requirement. Then add up the amount of calories you burned up through exercise. You should undercut the result by a maximum of 20%!

When does endurance training actually lead to muscle loss ...?

30-40 minutes of endurance sports are not only uncritical, but also beneficial for building muscles.

How about longer training units - a lot helps a lot? Not quite.

In my experience from marathon training, there are four training situations that can slow down muscle growth:

  1. Fatigue - the standard variant. If you go straight to the studio after an intense or longer endurance session, you can literally throw your strength training in the bin. You will then certainly no longer be able to set an intensive training stimulus. You previously wasted your ammunition in endurance training, but the explosive power is no longer sufficient for explosive muscle growth.
    The solution: ammunition beforehand. If you pay attention to your diet after endurance training and then pause 4-6 hours BEFORE you start strength training, your glycogen stores will be regenerated and you will be able to train more intensively.
  2. Fatigue is a tough job. I'm talking about endurance training up to the absolute limit. Depending on the training level and intensity, you can reach this limit after 3-16 hours of endurance sports. Anyone who has ever pushed to the limit in a marathon knows what I'm talking about. After such a stress stimulus, your body first needs a break for repairs and maintenance before effective strength training is possible again. In marathon training, I never do a long run and muscle training on the same day. In marathon training, my body is used to a high training volume. Then it's okay for me to hit the irons the day after a long run. Every body is different here, find out the right regeneration time for you (and let us know, write a comment!).
  3. Injuries. Often it is not endurance sport itself that is the problem, but related injuries from overuse. After all, you perform certain movements for hours without a break - again and again. At some point, the target is usually achieved. Weight training with pain is a no-go! In this article, you will learn how to deal with a sports injury.
  4. Overtraining. If you overdo it with the scope and intensity of your training, you can end up overtraining. Even if the danger is often hyped, in my experience it is very difficult to actually slip into overtraining. I have only "succeeded" twice in over 10 years of marathon training. The symptoms are pretty straightforward: a dramatic drop in performance for no “apparent” reason, acute reluctance to exercise, and a bad mood are among the most noticeable factors.
    Solution: If you should have overtrained, you can solve the situation quickly and easily with these measures.

What Does Science Say About Loss Of Muscle Through Endurance Training?

In fact, there is an interesting scientific publication on extensive endurance and muscle loss.

In a study carried out by the Ulm University Hospital in 2010, the body composition of the athletes during the Trans-European Run was examined.1 In this ultra run, the boys and girls covered almost 4,500 km in 64 days, which is around 70 km per day.

The results of the study are surprising: Obviously, the athletes have lost a lot of fat. But interestingly, the runners did noLose muscle mass on the upper body, but only on the legs.

Why on the legs? The muscle breakdown in the legs is most likely related to the lack of regeneration of the muscle tissue with such a long-lasting load (see basic principles of regeneration and recovery).

As with all studies, however, you should also see this result from the right perspective. Would a bodybuilder lose muscle mass if they trained for a 70 km ultra run? Most likely yes: if only because he would have to reduce his strength training in favor of endurance sports.

But with a 30-60 minute cardio session, you don't have to worry if you follow the principles above.

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At this point I would like to make a point about the alleged "muscle loss through endurance training" ...


If the Transeuropean runners can run 6 hours a day without losing muscle mass, then you can every day just like that Do 30-60 minutes of cardio without risking muscle breakdown.

Your body is an intelligent system. He will not give up his muscles easily if you listen to him. This includes not running 4500 km straight, getting involved in crash diets and, above all, having fun doing it. If you've always enjoyed training, then reluctance can be a sign of overtraining ...

How do you combine strength and endurance training? What experiences have you made with muscle loss and endurance training or not just made? Write a comment.

Photos in the article “Muscle loss through endurance training”: © iStock / 4x6, © Shutterstock.com: tacar, Giuseppe Parisi, "Rab Dunny Marathon I_MMVIII" by D. Sinclair Terrasidius (CC BY 2.0) via Flickr, "paper airplane" by woodleywonderworks ( CC BY 2.0) via Flickr

  1. Jürgen Machann, M.D., Christian Billich, M.D. New Study Reports Effects of Endurance Running. Radiological Society of North America. 2010 [↩]

Category: Nutrition, muscle buildingTags: endurance sports, protein, marathon, muscle loss, muscle building training, muscle fibers, muscle growth, protein, regeneration