Nothing!
Exertion
Lactic acid is a byproduct of muscular over exertion.
The level of exertion at which you are exercising.
Force: The amount of exertion on a body
The level of exertion at which you are exercising.
After a long day of hiking, Maria felt exhausted from the exertion of climbing steep hills.
The act of exerting, or putting into motion or action; the active exercise of any power or faculty; an effort, esp. a laborious or perceptible effort; as, an exertion of strength or power; an exertion of the limbs or of the mind; it is an exertion for him to move, to-day.
To watch another carrying a load requires no exertion.
The word exertion has three syllables. (ex-er-tion)
No. It is one that has little or no physical exertion.
It can not be clear why your body is hurting, it could possibly be from over exertion. Visit a physician to obtain a diagnosis.