Generations of athletes, from youth leagues to professional sports, were taught to stretch before practice and games to improve performance and prevent injury. The routine typically went something like this: Stand on one leg, hold your heel to your hiney, and count to 10.
Then, about 20 years ago, studies began to suggest that stretching could actually worsen performance and increase injury risk, creating widespread confusion that persists today. The problem is that many of those studies looked at stretching in a vacuum, says David Behm, author of The Science and Physiology of Flexibility and Stretching. The kind of stretching that was most often assessed in research was almost always static, and typically not preceded by any warm-up nor followed by any dynamic movements prior to diving into the actual sports.
Behm began playing competitive sports at the age of 6. He was drafted to the Canadian Football League, but was cut after one game for — as he says — not being fast enough. He later became an amateur provincial champion in both tennis and squash, and now he studies exercise science at Memorial University of Newfoundland. He says his own research and experience has convinced him that stretching still has value.
“I am 62 years old and still playing tennis, squash, and hockey against youngsters who are 30 to 40 years younger,” he says. “I am not as fast or strong as I used to be, but I ensure that I do both static and dynamic stretching before I play and I have not had a musculotendinous injury in decades.”
David Behm discusses the intricate biomechanics of stretching, and different approaches for general flexibility vs. a good pregame stretch.
In a review of hundreds of studies, Behm and his colleagues found that static stretching combined with an initial warm-up and some dynamic stretching — which involves actively moving muscles through their range of motion, as in walking lunges or torso twists — followed by sport-specific activities, such as swinging a baseball bat, can improve performance and reduce injury risk. Of the reliable studies in the review that looked specifically at injuries, there was “a 54% risk reduction in acute muscle injuries associated with stretching,” the researchers wrote in 2016 in the journal Applied Physiology, Nutrition, and Metabolism.
Stretching anywhere from about 20 seconds to four minutes softens muscle tissue and temporarily lengthens muscles up to about 5%, says Markus Tilp, a professor in the Institute of Sports Science at Austria’s University of Graz. That allows for greater range of motion in the joints , though the effect is temporary, says Tilp. After six weeks of stretching five times per week, this increased range of motion tends to lock in, but not because the muscles are permanently lengthened, Tilp and colleagues found in a 2014 study. Rather, somewhere in the signaling system from nerve endings to the brain, people adapt to tolerate a stretch that would once have hurt.
“We have receptors in our muscles, tendons, and ligaments that assess the length or position of a tissue and transfer this signal to the brain,” says Tilp. “Stretching seems to alter this sensation.”
It’s unclear if the adaptation occurs in the nerves or in the brain, but the most recent study by Tilp and colleagues, detailed in March in the Journal of Musculoskeletal and Neuronal Interactions, suggests it happens “at the brain level and how the signals are processed,” he says.
Stretching can also be useful for people who might otherwise be inactive. A 2016 study in the International Journal of Health Sciences found that after a 10-week stretching program, a group of 50 inactive people averaging 60 years old experienced improved balance, which the researchers say would reduce the number of falls, which are a leading cause of debilitation among the elderly. Another study, albeit a small one, in the Journal of Exercise, Sports & Orthopedics, showed that after a year on a static stretching program, people in the study ages 67 to 80 were more flexible, and their major muscles were stronger by 10 to 17%.
Even static stretching that was once viewed as questionable is considered okay if done in the right way. Static stretching, in combination with a warm-up routine and followed by sport-specific dynamic stretches, has benefits, some of which are mental and even social, says Anthony Blazevich, who leads the Center for Exercise and Sports Science Research at Edith Cowan University in Australia.
“Stretching time allows for kids and athletes to check their muscles to look for tightness or soreness,” Blazevich says. “It also gives the team time to talk, bond, or listen to coach instructions.”
Research has even suggested that stretching makes athletes feel more prepared to perform, regardless of whether it actually prepares their bodies. “It’s also useful to stretch after sessions,” says Blazevich, who worked with Behm on the large 2016 review of stretching studies. “Research indicates that this stretching is associated with a reduction in future injury.”
There are limits to the power of stretching, however. Blazevich led another study last year to test a variety of stretching routines on serious athletes — young men who played competitive team sports. On different days, the men took different approaches to static and dynamic stretching, as part of long warm-up periods, before testing their abilities to sprint, jump, and change direction.
“Participants felt they were more likely to perform well when stretching was performed as part of the warm-up, irrespective of stretch type,” Blazevich and his colleagues wrote in the journal Medicine & Science in Sports & Exercise. “However, no effect of muscle stretching was observed on flexibility and physical function compared with no stretching.”
What’s the best way to pull the latest science into a routine? Behm suggests thinking of stretching in two ways. First, it should be a daily activity.
“If you want to be the ultimate weekend athletic warrior and participate every week without muscle and tendon injuries, you should stretch on a systematic basis,” Behm says. “Stretching to increase range of motion should be performed as a separate workout and not just before a workout or a sport. So instead of just lying or sitting down passively in the evening to watch the TV news, get down on the floor and static-stretch the major muscle groups for two to three repetitions of 30 seconds each.”
The key is to stretch until you feel tension, not pain or extreme discomfort, he says.
“To get even better results, massage the muscle tendon while you are stretching, as we have found that this tendon massage actually increases your range of motion more than just stretching alone,” Behm says. “If you are really keen you could also use a foam roller or roller massager to roll the muscle first and then stretch it.”
Second, it’s important to stretch immediately before playing sports or doing your workout, but incorporate a warm-up and a mix of static and dynamic stretching. The research is clear on the value of warming up. “You may hurt yourself if you stretch cold muscles,” says the Mayo Clinic’s guide to stretching.
Behm suggests a rough guide to pregame activities:
“This full warm-up will help to prevent muscle and tendon injuries and get your body prepared for action,” Behm says.
For people looking for a less time-consuming approach, Behm recommends that after a light warm-up, people should do short stretches of 10 seconds or less of all major muscle groups to check for tightness or injury, and to help with mental preparations for exercise. “Then continue with the more intense and sport-specific phase of the warm-up,” he says.
At the end of the day, the takeaway is that if it feels good, do it.