It depends on what kind of stretching you’re doing, says Dr Alex Dinsdale, senior lecturer in sport and exercise biomechanics at Leeds Beckett University.
Injuries, he says, happen for all sorts of reasons, from poor footwear to fatigue. Two key factors are not having the range of motion required or not being strong enough to control that motion. “You might go for a run and lift your knees higher than your hamstrings can manage,” he says. Or you might lack the muscle strength needed to handle moving a limb at speed.
When people talk about stretching, they usually mean static stretching: holding a pose for six seconds or longer to elastically deform the muscle. “Static stretching can increase your range of motion, but it also decreases the force a muscle can apply by about 5%,” Dinsdale says. Dynamic stretching (moving through a stretch, by doing exercises such as bodyweight squats or walking lunges) has more balanced benefits. “It doesn’t increase range of motion as much, but it can increase the muscle’s capacity to produce force.”
For most of us, the best pre-exercise routine is a warm-up involving light movements similar to the workout ahead, such as a fast walk before jogging. “Increasing the temperature of your muscles helps them produce force more effectively, and you gain a bit more range, too,” says Dinsdale. After that, a few dynamic stretches can guide your body through the motions you’re about to perform. To finish, he recommends powerful movements to prime the neuromuscular system – “a few jumps, or a short, sharp sprint”.
What matters more than warm-ups is what he calls “assistance training”: dedicated strength training and static stretching sessions, at an alternative time to your chosen exercise, to build strength and flexibility in the muscles you rely on for your activity.
