It's either the satisfying relaxation at the end of a hard workout, or one more thing keeping you from that snack and shower waiting at home. What good is a cooldown, and should you delay that snack and shower to be sure you get one in? Or are all those happy cooldowners wasting their time?

Before we can figure out whether cooldowns work, we need to decide what they're supposed to do. I've heard everything from flushing lactic acid to preventing soreness to making sure you don't faint or get dizzy. Some of these are more plausible than others. Nobody seriously believes any more that lactic acid needs to be flushed from your muscles or that it does anything bad while it's there.

But soreness and fainting are definitely great things to avoid if you can. Does a cooldown help prevent these?

Soreness

If by "cooldown" you mean "sit down and stretch for a while," we already know the answer to that one: stretching doesn't prevent soreness. But a more active cooldown, like walking after you've finished a run, is worth another look.

A study of professional soccer players in Spain tested an active recovery session (12 minutes of jogging followed by eight minutes of stretching) versus sitting on a bench for 20 minutes after practice. Each player did both options on different days, and the thrilling results were that everybody recovered about the same no matter what they did after their workout. There was no difference between the two in their muscle contraction as measured by tensiomyography, or in their perception of soreness 24 hours later.

Another study, this one out of Norway, pitted warmups against cooldowns. The volunteers were all healthy adults in their twenties (21 men and 15 women) who were physically active but not competitive athletes. Their assigned workout was 10x5 front lunges with a barbell carrying 40 percent body weight for women, 50 percent for men. Paired with this workout, a 20-minute session on a stationary bike reduced soreness if it was performed as a warmup, but had no effect when it was done as a cooldown. Meanwhile an Australian study of backwards downhill treadmill walking (try that next time you're at the gym, I dare you) had similar results: a (forward, uphill) walking warmup helped a little; the same as a cooldown did nothing.

Fainting and dizziness

After intense exercise, it's possible for blood to pool in your arms and legs, leading to a temporary lowering of blood pressure that can make you dizzy or even pass out. If this never happens to you, you're off the hook; skip to the end. But if this is a familiar feeling for you, or if you're at greater risk because of heart disease, a cooldown may be in order.

Compared with sitting around, an active cooldown helps return your heart rate to normal a little bit faster, which should prevent the dizziness. But a formal cooldown may not be necessary for this; one physiologist explained to a New York Times reporter that walking for a few minutes is all it takes, and you're probably doing that (to the locker room, to your car) anyway.

What's a cooldown good for?

It's important to note that cooling down is never bad for you; there aren't any downsides aside from the thought of that shower beer being lonely waiting for you to come home from the gym.

A cooldown, if you can spare the time, is a great time to do some mobility exercises or to tack on any extra work you might not do otherwise. Runners, for example, may want to throw in an extra easy mile or two after a tough workout as a way of adding to their total mileage for the week. And if you're going to do static stretches, you sure don't want to do them before a workout (they reduce strength for a little while). Instead, the end of the day is the perfect time.

So if a cooldown is your moment of Zen, by all means take advantage. Enjoy your walking, your stretching, your savasana (that's yoga for "collapse on the floor because you feel like you want to die" and I'm only mistranslating slightly). Just know that, as long as you haven't actually fainted, the benefit is mostly mental.