These two poses are not only great for your hamstrings, but also for the spine. Stand tall with your feet hip-width apart. Fold down from the waist and grab your elbows overhead. This pose is called rag doll. You can keep the knees bent as you fold forward, and with time, slowly try to straighten them out a bit. This stretch can also feel really nice for your back. Bend your knees a little more and let the upper body hang down. Shake your head and feel free to swing gently from side to side to release any tension that you may have built up in the back and neck.
For a deeper stretch on the hammies, try grabbing the big toes with your pointer finger and middle finger. Come half way up and straighten out your back, pull on your big toes and pull yourself closer towards the legs. By bringing the elbows towards the side, you make room for the neck and head.
These were just a few yoga poses for runners to stretch out their leg muscles. Of course there are many more ways to do so! Remember that all bodies are different, so what might work for me, might not be the same for you. So go ahead and give these poses a try, and modify wherever you need to. Always listen to your body and respect your boundaries. Use your breath in the poses to calm the mind and ease the stretch.