from The New York Times
Do you often, if guiltily, skip cooling down after exercise? A small but soothing body of new research suggests that you aren’t missing out on much.
Most of us were taught in elementary school gym classes that the body requires a formal period of cooling down after a workout or competition. Instructors told us that by slowing to a jog or otherwise lessening the intensity of the workout, followed by stretching or otherwise transitioning out of physical activity, we would prevent muscle soreness, improve limberness and speed physiological recovery. All of this would allow us to perform better physically the next day than if we hadn’t cooled down.
But under scientific scrutiny, none of those beliefs stand up well.
In a representative study published last year in The Journal of Human Kinetics, a group of 36 active adults undertook a strenuous, one-time program of forward lunges while holding barbells, an exercise almost guaranteed to make untrained people extremely sore the next day. Some of the volunteers warmed up beforehand by pedaling a stationary bicycle at a very gentle pace for 20 minutes. Others didn’t warm up but cooled down after the exercise with the same 20 minutes of easy cycling. The rest just lunged, neither warming up nor cooling down.
The next day, all of the volunteers submitted to a pain threshold test, in which their muscles were prodded until they reported discomfort. The volunteers who’d warmed up before exercising had the highest pain threshold, meaning their muscles were relatively pain-free.
Those who’d cooled down, on the other hand, had a much lower pain threshold; their muscles hurt. The cool-down group’s pain threshold was, in fact, the same as among the control group. Cooling down had bought the exercisers nothing in terms of pain relief.
Similarly, in two other studies published last year, one in The Journal of Human Kinetics and the other in The Journal of Strength and Conditioning Research, professional soccer players in Spain underwent a series of physical tests to benchmark their vertical leap, sprinting speed, agility and leg muscle flexibility, and then completed a normal soccer practice. Afterward, some of the players simply stopped exercising and sat quietly on a bench for 20 minutes, while others formally cooled down with 12 minutes of jogging and 8 minutes of stretching.
The next day, the players repeated the physical tests and also told the scientists how sore their legs felt, an assessment with which professional athletes tend to be familiar.
It turned out that there were almost no differences between the two groups of players. The cool-down group could, on average, leap a little higher the next day than those who’d sat around for 20 minutes, but the difference was slight. And on all of the other measures of performance, flexibility and muscle soreness, the groups were the same.
The available data “quite strongly suggest a cool-down does not reduce postexercise soreness,” says Rob Herbert, a senior research fellow at Neuroscience Research Australia and senior author of what is probably thefoundational study of cooling down, from 2007. In that experiment, healthy adults walked backward downhill on a treadmill for 30 minutes, courting sore muscles and curious stares from fellow gymgoers. Some of the volunteers first walked forward for 10 minutes as a warm-up; others did the same afterward, to cool down. Others didn’t warm up or cool down.
Two days later, the group that had cooled down was every bit as sore as the control group.
Given all of these findings, then, is there any valid reason to cool down?
Yes, says Andrea Fradkin, an associate professor of exercise science at Bloomsburg University in Pennsylvania. “A cool-down has been shown to prevent venous pooling after exercise,” or the buildup of blood in the veins, she says. During prolonged, vigorous exercise, the blood vessels in your legs expand, meaning that more blood moves through them. Stop exercising abruptly, and that blood pools in your lower body, which can lead to dizziness or even fainting.
The condition is easy to combat, though. Just walk for a few minutes at the end of a workout and you’ll maintain normal circulation to the brain, says Ross Tucker, a South African physiologist and a founder of the estimable Web site The Science of Sport. “And that’s not really a cool-down,” as most of us would define the procedure, he says.
Still, if a formal cool-down provides few confirmed physiological benefits, it may have a scientifically squishy, but nevertheless worthwhile psychological effect. “If you’ve done a very hard track session, it’s nice to end with some light jogging,” Dr. Tucker says, just to restore a subjective “sense of normality to your legs.”
A cool-down, in other words, feels nice.
And it’s important to note that “none of the scientific research shows any negative effects due to performing a cool-down,” Dr. Fradkin says.
So, in essence, the available science suggests that whatever you’re doing now at the end of a workout is probably fine.
“My feeling is that” unless future science shows otherwise, “people shouldn’t worry about it,” Dr. Herbert says. “If they like to cool down, then it’s not going to hurt them. But if they don’t feel like it, then they shouldn’t feel a need to do it.”