Several years ago I wrote about getting the warm-up right, and I still believe that many runners neglect the warm-up to their own detriment. But after you work out, what about the cooldown (or, less commonly these days, a “warm-down”)? How long, how far, and how fast should a cooldown be? Getting to a place where we can answer these questions is going to require getting a framework in place where we understand why you should cool down in the first place.
Understanding the reasons for doing a cool-down after a workout
Like much of the accumulated lore of running, the common rationales for doing a cool-down at all contain a healthy mix of physiology, bro science, folk wisdom, and true coaching wisdom. Allegedly, the cooldown is supposed to gradually reduce your heart rate, pump “lactic acid” out of your muscles, and condition your legs to running while tired. Failing to cool down is again allegedly supposed to make you feel more sore the next day, and harm your recovery capabilities. Needless to say, each of these rationales has a hefty amount of myth alongside perhaps a kernel of truth.
Instead of trying to consider and analyze each of these claims in turn, I think it’s better to break the question of “why do a cooldown” into smaller parts: who is doing the cooldown, what workout does it follow, and what training goals are we trying to accomplish, both in this workout and in the longer-term training plan.