I grew up knowing that as much exercise you do as much benefit you get!
Last week, I met somebody who is studying Exercising Biology, and she said that if you did exercise to much, you would have more problems when you get older.
I know that in some cases, such as doing hard and extreme extremes such as Gymnasium extremes too much and hard is harmful. Running to fast and too much might cause problems in the knees. Also, exercise hardly with warm up is also harmful. Beside taking some special tablets, I don't know what they are called, for building muscle is also harmful.
But I had never heard that regular exercise even doing them a lot progressively is harmful. What I know is that if you exercise a lot, you will see the benefit when you are older.
I know I wrote a lot, but I am really confused, can you help me?
You made really good points I was lokking forward, but I have some question about your coment.
How can I know if it is "good" burn of muscle or not.
I know that I can't run marathon from the first day, but if I arrived to that level. Then I continue increasing gradually. Woud it be harful because I am doing a lot of running even though I did it gradually Also, is it the same for other kinds of sport as well?
Some exercises can cause damage to bones, muscles and surrounding tissues, make it more likely that you will injure yourself or worsen a pre-existing injury or medical condition. Avoid bouncing while stretching, standing toe-touches (touching your toes), full squats, sit-ups (crunches) and double leg raises. They can all cause injury.