Hi could you explain what happens when your quadriceps muscle stops working? can this effect your knee pain? what exercises are good for the quad muscle? thank for helping.

Question unclear and: Details matter, such as what a person means by "muscle stops working." The quadriceps are the huge muscles that extend (straighten) the knee. Any problems with the quadriceps (quads) will affect the knee and affect walking, running, standing, getting up and down from a chair or from the floor, etc... One's primary care doctor can evaluate and see where to go next.