Q What’s the purpose of cooling down after a hard work-out? It seems like such a waste of training time. What happens if I don’t do it?
A If you skip the cool-down, it’s unlikely that any great tragedy will befall you. Nevertheless, there are many good reasons for cooling down, not all of them scientific. For one, a nice, slow jog gives you an opportunity to savour the achievement of completing a work-out, and a chance to swap laughs with your training partners once the hard work is done.
Physiologically, cooling down helps your body make the transition from intense running to normal activity. More specifically, a 5 to 10-minute post-training jog or walk prevents blood from pooling in the legs, which can happen after a hard run. This limits blood flow to the heart and brain, and can lead to dizziness, nausea and other problems. Slow running will keep blood circulating around the body.
As for fitness benefits, end-of-session jogs can be used to turn medium-mileage runs into higher-mileage days. A couple of extra miles at the end of a regular work-out will train your body to keep moving even when it’s tired. This is especially useful if you’re gearing up for a longer race such as a half-marathon or marathon.
There is no clear-cut evidence that cooling down reduces subsequent soreness or prevents injuries. Still, the cool-down period is a good time to stretch, since warm muscles can be stretched more easily than cold ones. I generally follow my own cool-down with quad, calf, hamstring and back stretches for 10 minutes.
—Greg Crowther, assistant professor of biology and 2:22 marathon runner