What it is: After a long, hard run, sore muscles begin to kick in. Small tears in the muscle fibers cause the achiness, but it's a sign that your body is getting stronger.
How to prevent it: Always do a proper warm-up before jumping right into a run, and when you do get going, start off slow. When changing up your running workout, either by adding hills, picking up the pace, or increasing the distance, do so gradually. If you experience soreness after a run, treat it with a hot bath, massage, a good stretching session, or some light exercise. Eating these foods may also reduce pain.