As part of your warm up before you run you can do a few stretches. A few stretches is for your hip flexor, your ham string, your quad, and calf. Now before you do your run you want to do a dynamic stretch verses static stretch. So you want to do dynamic stretches verses static stretches. But with dynamic stretching you’re doing short abbreviated stretches to warm up your muscle. You want to stretch your major muscle group before you run. Those will be your hip flexors, your quads, hamstrings and your calf muscles. You want to warm up your muscles because it helps to warm up your body, and it helps your body to adapt a little bit to the exercise you are about to do.