When is appropriate to stretch? Before or after activity? I wish I had a definitive answer for you, but it depends on whose philosophy to which you subscribe. Much like the barefoot debate, each side has their own story. Here’s what I can offer you.
One study says that sprinters benefit from static stretches held up to 90 seconds, along with a dynamic warm-up. Another study tells us that we gain more hamstring flexibility from dynamic stretches than from static stretches before activity.
Certainly, researchers seem to agree that we should not stretch cold muscles. My plan is to warm-up with some dynamic movements that increase my range of motion. Perhaps some leg swings and some arms swings before my run, with mile one being a warm-up mile. Post-run, for me it is important to get in a quarter mile walk for my cool-down and some very short, 10 second hamstring and hip stretches, repeated a few times.
As with most things in life, we have to find our own truths. We are all different and we should experiment to find works best for each of us!