Should we stretch before exercise?

A thought-provoking new experiment with athletes suggests that the answer could depend on how we feel about stretching and what kind of exercise — and stretching — we intend to do.

Once, stretching before team sports and other activities was almost ubiquitous, especially so-called static stretching, during which you assume a pose and hold it for anywhere from a few seconds to several long minutes.

But static stretching has fallen out of favor in recent years, after studies showed that prolonged static stretching might cause reactions in the nervous system that temporarily weaken the stretched muscle. Consequently, athletes would not spring quite as high or sprint quite as fast after lengthy bouts of static stretching.

So, many coaches and organizations, including the American College of Sports Medicine, began to advise against static stretches and advocate instead for dynamic stretching, during which limbs and joints stay in motion.

During a static stretch of your quadriceps muscles, for example, you might stand up, grasp one foot, ease it up until your heel touches your backside and stay in that position.

A dynamic version of that same stretch would entail tugging your foot a bit farther up your back, then releasing your foot to the floor, and repeating the motion multiple times. It was thought that such dynamic stretching should bypass any negative impacts on performance, while helping muscles and joints to warm up and prepare for intense activity.

But little research has examined the actual performance effects of dynamic stretching.

So for the new study, which was published in June in Medicine & Science in Sports & Exercise, a group of international scientists, many of whom work with elite, national-team athletes, decided to test different stretching routines.

They began by recruiting 20 young, male athletes who play team sports like soccer or rugby that involve running, sprinting and sudden shifts in direction — activities that are believed to demand a thorough warm-up.

To control for placebo effects, the researchers asked the athletes what kind of stretching, if any, they each expected would aid their performance. Almost all named dynamic stretching.