Your hamstring muscles, which run down the back of the leg from the pelvis to the lower leg, are prone to injury, so it's very important to stretch them. Here's how to do a hamstring stretch:
1. Stand with your legs crossed and the outsides of your feet together.
2. Bend over with your rear knee straight.
3. Reach toward your feet or bring your torso toward legs.
4. Hold stretch for 15 to 30 seconds. Repeat with your opposite leg.
Get more running stretches.