What changes occur in the muscles during exercise?

Answer 1

I'll give you the basics of it:

When you exercise and you feel that burn during and after a workout, that is the muscles fibers tearing up. After your workout it is very important to eat well because the process of your muscles rebuilding takes longer that it does to tear them up. The muscles will repair and rebuild bigger than before you exercised. You could work out vigorously and not eat right and you wouldn't gain much muscle. Eating right and working out itself are equally important. A common misconception is people believe you need to spend hours a day at the gym in order to build muscle. It can be as easy as working out one area of the body (arms) once a week doing no more than 5 separate exercises. The most important thing to do while working out: doing it right (technique is everything).

Answer 2

Since muscles are the part of the body that allows you to do vigorous exercise, they are generating quite a lot of heat. This is because the muscles are contracting, which then causes friction between adjacent muscle tissues.

Answer 3

Muscle cells break down, and then a day later rebuild thicker and stronger.

Answer 4

Your muscles use oxygen till it runs low. After a while it will produce lactic acid instead which leads to muscle soreness.

Answer 5

Exercise causes microscopic tears and damage to a muscle. Resting allows the muscle to repair itself and make itself a bit stronger for the next time exercise is performes.