A beginner comes after training with a feeling of happiness associated with the start of a new life in a beautiful and toned body. He feels satisfaction with the work done and wants to return to the gym tomorrow, falling asleep with these thoughts. 
But everything changes when a novice athlete wakes up and feels severe pain in his trained muscles the day before. Why muscles ache after physical exertion - this and other questions will be devoted to the article.
Causes of Muscle Pain
To determine why muscles hurt, you need to get to the bottom of the causes of pain, which can be several. Imagine the main ones:
- Tear, muscle break.
- Damage to the joint, connective tissue.
- Serious for the current level of microtrauma training.
- Exposure to lactic acid.
The first option is a sharp muscle pain during and immediately after training.
The second option is related there, noting that for a combination of several reasons, you can take joint pain for muscle pain. This item also answers the question of why muscles hurt after running. The fact is that during running exercises, not only the muscles of the legs, but also the joints, which can also hurt, experience an increased load.
The third and fourth causes of muscle pain are synonyms of their kind. Where there are serious microtraumas, there is lactic acid. Muscle pain some time after completion of the workout (most often manifests itself the next morning) is a clear sign of exposure to excessive microtrauma and lactic acid.
Many are interested in the question of why muscles hurt a day after a workout. This is due to the fact that the accumulation in the muscle fibers of lactic acid occurs gradually. And when its greatest concentration is reached, the person experiences pain.
How to get rid of muscle pain
Most often, beginners do absolutely nothing to prevent the occurrence of pain in the muscles the next day. As a result, the next morning, even getting out of bed becomes a laborious task and the question arises why muscles ache after exercise and what to do with pain. 
This can be avoided by performing some activities immediately after training:
- Stretching. To partially “drive off” lactic acid, you can try to stretch right after exercise. It is worth devoting 5-10 minutes to warm up, so that the next day you feel like a full-fledged person.
- No rest! Immediately after training, in no case should you relax. If classes are held in the gym, then you need to walk at least 20-30 minutes before you get in the car (minibus, bus) and go home. You can also run as an additional warm-up or recall your childhood by jumping for five minutes on a skipping rope. If training takes place at home, the best way would be to arrange a short walk right after class. The body in the morning will say thanks for these half an hour in the fresh air.
- A hot bath is a way to relax, getting rid of lactic acid. Such a bath is often advised to be used the day after training, when the physical condition is already deplorable. But better to warn than to cure. And most often, when it comes to first training, the body asks for relaxation, and a hot bath is the best way to do this. An hour spent in a hot bath or bath will help relieve muscle pain and also prevent soreness in the morning.
The next day…
Well, if the condition is already running and in the morning the question is why the muscles hurt after training, what to do, then you need to try the following:
- First you need to take a hot bath.
- Then repeat yesterday's workout in light mode, despite the muscle pain present. If the muscles are not stretched now, then they can hurt for another week. Yes, at first it will hurt, but after training, you will feel relief, and the disturbing symptom will disappear after two or three days, and not in a week, as it happens if you do nothing the next morning after class.
- It helps to eliminate pain massage and special creams.
The next time it is advisable to do the exercises in a gentle manner so as not to tear muscle tissue again. The number of such facilitated activities is determined based on the physical condition of the athlete.
The main thing is not to be afraid of pain and not to overdo it
Muscle pain is a natural occurrence for the first workouts. Most likely, when doing stretching, taking a bath and walking around the gym immediately after training, the athlete will still feel some soreness the next morning. And it is not a question of lactic acid, the effects of which can be quickly safely eliminated, but of microtraumas of muscles that are too serious for an untrained body. Do not be afraid of this. The muscle pain caused by microtrauma will go away without causing any harm to the body. 
But to answer the question why muscles hurt after physical exertion, one more thing to remember. In order to avoid the symptom of overtraining, you do not need to be too zealous in the first lessons. It is necessary to allow the body to get used to physical activity, to work on the technique of exercises instead of storming the desired result. This tip will help you get rid of quickly or not really feel muscle pain after the first workouts.
Moreover, it does not matter where the classes are: at home or in the gym. For a body that has not experienced any significant stress for a long time, training is a serious test. That's why muscles hurt after physical exertion. You need to finish the exercises before you feel that there is no more strength for training.
At first, it’s better not to train than to train. This must be remembered.
When you need to sound the alarm
You need to start worrying in such cases:
- It is impossible to move any part of the body.
- Trained body part is swollen.
- Muscle pain does not subside for more than a week.
In other cases, we are talking about banal lactic acid and overtraining, which will not cause any harm.
If, nevertheless, there is some concern about the physical condition, then you do not need to postpone the visit to a traumatologist or sports doctor. Specialists after a thorough examination will give the necessary recommendations and advice.
Muscle pain with regular exercise
Everything mentioned above is dedicated to beginners. And this is not surprising, because it is precisely those who exercise less than three months who most often suffer from muscle pain. And for them, the question of why muscles hurt after exertion is especially relevant.
It is believed that the body of a person who has been practicing for years is getting used to the loads, as a result of which serious muscle pain is impossible. Upon learning of this, men and girls who have been training for several years begin to sound the alarm. But this is not necessary. In people who regularly subject their body to physical activity, muscles can also hurt. Unusual or excessive stress - these are two factors that can cause muscle pain even with great training experience. The recommendations are the same: if the pain gradually subsides, there is no reason for excitement. Otherwise, a doctor’s consultation is indicated.