Stretching before or after running: Is there a topic runners argue over more? The only more debatable topic might be whether to stretch at all.
In my years of running, I have found evidence supporting both sides of the argument from doctors, physical therapists, and athletes. Who to believe? Ultimately, this is true with most things in running. You have to learn to listen to your body.
To start, why are we even talking about stretching? "A lot of people don't understand that stretching has to happen regularly. It should be daily," says David Nolan, a physical therapist at Harvard-affiliated Massachusetts General Hospital. Stretching keeps the muscles flexible, strong, and healthy, and we need that flexibility to maintain a range of motion in the joints. Without it, the muscles shorten and become tight. Then, when you call on the muscles for activity, they are weak and unable to extend. That puts you at risk for joint pain, strains, and muscle damage. For example, sitting in a chair all day results in tight hamstrings in the back of the thigh. That can make it harder to extend your leg or straighten your knee, which inhibits walking. Likewise, when tight muscles are suddenly called on for a strenuous activity that stretches them, such as playing tennis, they may become damaged from suddenly being stretched. Injured muscles may not be strong enough to support the joints, leading to joint injury. Regular stretching keeps muscles long, lean, and flexible, which means that exertion "won't put too much force on the muscle itself," says Nolan. Healthy muscles also help a person with balance problems to avoid falls.
There are two types of stretching: static and dynamic. Static stretching is the bend-and-touch-your-toes type of stretch you remember from gym class. Dynamic stretch involves range of motion and bounding, such as leg swings, body rotations, and skipping.
What to do? I suggest not stretching before a run or dynamic stretch, only if you need a starting point. Most professionals agree that static stretching before a run can lead to injury. Cold muscles can pull, tear, or strain because blood flow is low. A warm muscle has increased blood flow, which makes the muscle tissue more pliable and receptive to change in motion. In my mind, I imagine a kitchen sponge. A dry sponge (cold muscle) is susceptive to breaking under strain, while a wet sponge (warmed muscles) is workable and flexible.
I do not stretch before a run. I will start with a light warm-up jog for 10 to 20 minutes. If I still feel tight after a warm-up, I proceed with some static stretch. I'll focus on my hamstrings, calves, and quads. The exception is workout days and cold weather days, where I have found beginning with dynamic stretching is helpful, notably leg swings.
However, some people do static stretches before a run. What is the argument for that? Well, your legs tend to feel better stretched, and your stride is open and longer. If you insist on static stretching before a run, start with some dynamic movements first. Bounce around, swing your legs. That will get some blood flowing to your muscles. Then, you can proceed with static stretches if you remember to take it slow and with an awareness that cold muscles have a higher chance of tearing.
No matter what you decide, best wishes on chasing your running goals.