Science of Exercise

No.12673698 ViewReplyOriginalReport
What is it about exercise, exactly, that is so great for you?
Take this runner for example
Aside from burning calories:
1) you are putting tons of pressure on your joints if you run, making it more likely you will be a cripple at 80
2) You make your heart have to work harder to pump blood, making it likely to wear out faster
3) You spread germs by touching weights that 600 other people just touched after wiping their butt in the bathroom.
4) you contribute to the destruction of our planet by buying new running shoes every 6 months so you can take instagram photos
5) You include some muscles but exclude others because you want to look "buff" but in the process create inbalances in your body that will mess you up

So is there ANYTHING, scientifically speaking, that can be said for exercise?