Skeletal muscle fibers are cells, but unlike many cells in the body, they don't divide. They bulk up by joining together. Not using your muscles causes them to atrophy or shrink as the muscle fibers ...

Long hours of sitting can lead to back stiffness, reduced spinal mobility and muscle tightness, increasing the risk of ...

Haven't been to the gym in a while? Experts explain how quickly your progress declines ...

Plus, how to get the most of your walking workout.