If you knew your car had bad alignment, worn brake pads, and was over due for it's scheduled maintenance would you feel comfortable driving it on the freeway? Would you expect it to stop on a dime and handle well during stop and go traffic? Would you ignore the check engine light by covering it up? Obviously not. The body is no different. When muscle system quality is low and you jump into an exercise endeavor whether it be running, group classes, or weight training you are adding demands to a system that is already under stress and ill prepared to handle force. It’s only a matter of time until you're on the side of the road with the hood up wishing you took better care of yourself. Except when it comes to the body the parts are much more expensive to replace and they never quite work as well as the original.