Why do your muscles burn when you exercise? It’s simply because your muscles are not getting enough oxygen temporarily. There is more to it than that, which is what we will cover in this article.
We all know the feeling. You are working out and putting in reps. Towards the end of your sets, your muscles start to get fatigued, and you cannot keep up with the pain.
This is completely normal. The main cause of muscle fatigue is known as metabolic fatigue, which essentially just means lack of nutrients to your muscles. This can mean oxygen, calories, blood flow, etc…
Lucky for us, the majority of people that experience muscle pain is due to metabolic fatigue, and it is not something to be concerned about.
Reason 1: Lack of oxygen to the muscles
There is a reason that your heart pumps hard when you exercise. It is because every area of your body is fighting for oxygen. And now your heart needs to provide that by pumping blood to those areas.
Unfortunately, your heart does not have the capacity to pump as much blood as necessary to stop the muscle burn.
When you are working out, and really getting your muscles fired up, your muscles demand oxygen. When they don’t get the required amount, that is when the pain starts and you experience muscle fatigue.
This is nothing to worry about. As soon as you are done with your set, the blood eventually catches up to your muscles. And that is why we can now go and do another set without repercussions.
All of this eventually catches up to you for a day or 2 after your workout. All of the little muscle tears that you caused by working out need to be repaired. Again, your body has a tough time repairing these quickly. Luckily, you can learn how to make your muscles recover faster after a workout.
Reason 2: Lack of calories can lead to muscle burn
If you read my blog post with any regularity, you will know that calories mean a lot for everything that you do. If you want to lose weight, you need to eat at a caloric deficit. Having a desire to gain muscle, you need to eat at a caloric surplus.
These facts are so simple, yet some people refuse to acknowledge the reality of it. And calories play a major role in muscle recovery and muscle burn.
If you are eating at a caloric deficit, you are going to lose weight. This means that there are going to be less calories for your muscles to take in. Meaning that your muscles are going to burn more than if you were eating at a caloric surplus.
Eating at a caloric surplus is necessary to build muscle. You cannot build muscle while in a caloric deficit.
So what does this tell us about our muscles? Why do your muscles burn when you exercise while on a caloric deficit? Because important nutrients are being used elsewhere in your body. When you are losing weight, your body is not prioritizing your muscles.
When you are eating at a caloric surplus, the required nutrients are going to be readily available in your bloodstream which will definitely cut down on the possibility of muscle burn.
Reason 3: You might be pushing yourself too hard
There are a lot of reasons that you don’t want to push yourself too hard. Your chances of injury increase drastically when you go too hard.
I am guilty of this in the past. I would workout 5-7 days per week, pushing myself as hard as I could each day. Looking back, it is no surprise that I didn’t gain any muscle during that time period.
Not only was I pushing myself too hard, but I was also eating at a caloric deficit. This is a bad combination. I was doing too many reps, thinking that more was better.
This alone is why I highly recommend sticking to a plan. We have multiple FREE workout plans in our app All Workouts: Personal Trainer (iOS | Google Play).
If you don’t feel like downloading the app, I understand. At least check out our beginner bodybuilding routine for mass. There are also plenty of other workout plans on this blog. Just use the search function and you will find what you are looking for.
The whole point here is to have a plan and not worry about pushing yourself over the edge. There are some instances where pushing yourself is a good idea. Like high intensity interval training for example. But pushing yourself has to be calculated properly.
When you are doing a HIIT workout, your goal is to get to 90% of your maximum heart rate. I think that can be categorized as pushing yourself. In this instance, it’s ok, but that is because it is controlled.
Main Point: Why do your muscles burn when you exercise?
By now, you understand the 3 main reasons for why your muscles burn when you exercise. Lack of oxygen to the muscles, lack of caloric support, and pushing yourself too hard are just some of the reasons why your muscles burn.
Lucky for us, 2 out of these 3 things can be helped along with conscious activity. For example, if we want to build muscle, we can eat at a caloric surplus. This serves 2 purposes. It helps build muscle faster, and prevents muscle soreness.
Maybe we are pushing ourselves too hard. That can also be easily avoided by planning your workouts and rep counts per set.
All in all, muscle burn is part of the whole exercise experience. If your muscles aren’t burning at least a little bit, you might want to either increase your weight or increase your rep count.
I always like to go by the rule of the final 2. For your final 2 reps of each set, you should be struggling. If you are not struggling, increase your weight. That is the true way to make sure you are doing enough.
What are your thoughts on this? Why do your muscles burn when you exercise?
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