Anyone who’s ever taken a high school gym class knows the often repeated adage: Always stretch before exercising to prevent injury. While stretching before exercise is widely practiced — and even promoted by professional athletic trainers — science in recent years has begun to question the effectiveness of this traditional advice.
The questions of whether, when, why and how to stretch reach into a number of gray areas, and not all the experts agree. The American College of Sports Medicine advises stretching all major muscle groups at least twice a week and notes that regular stretching can help keep certain muscle groups flexible as people age. Stretching also can help with back pain resulting from prolonged sitting at a desk, the group says.
Some trainers say it’s the warm-up routine, rather than the stretching, that helps prevent injury when performed prior to exercise. Others advise stretching both before and after working out to increase flexibility, although expert opinion is mixed on whether traditional forms of stretching actually prevent injury.
In the early 2000s, several studies found no statistically significant benefit to traditional stretching prior to exercise. In one study, researchers at Charles Sturt University in Australia found that military recruits who stretched before exercise did not reduce their risk of injuries. In fact, the researchers suggested that the stretching was a waste of time.
The body of research suggests several reasons why traditional stretching may not be useful for preventing injury, including:
In the past decade, experts have shifted their recommendations away from traditional stretching, known as static stretching. In a traditional stretch, an exerciser moves a joint as far as it can go and holds the stretch for a predetermined length of time, typically 30 seconds to one minute.
Instead, experts now recommend a very different practice: dynamic stretching, which is based on controlled movements that gently take the athlete to the limits of her range of motion. Dynamic stretching works especially well for sports that require rapid bursts of activity, including tennis, basketball, soccer and sprints.
The Cleveland Clinic recommends properly warming up — including dynamic stretching — before exercise to prevent injury.
Dynamic stretching incorporates motions specific to the exercise to be performed, and it targets the muscle groups that will be used. Typically, athletes perform 10 to 12 repetitions of each dynamic stretch, which involves active movement of the muscles and joints.
This modern form of stretching increases blood flow and body heat, loosening tendons and muscles and reducing the risk of injury. Dynamic stretching also boosts flexibility by improving range of motion and, over time, can further reduce the risk of injury.
Traditional or static stretching does not lower the risk of injury because it cools muscles and can even weaken them. Static stretching may even increase the risk of injury, since it does not help athletes with specific movements and may negatively impact agility and balance.
To avoid injuries during workouts, experts now advise warming up beforehand and cooling down afterward. A proper warm-up can include jumping rope, riding an exercise bike or jogging in place for five to 10 minutes. Walking for five to 10 minutes after a workout is an effective method for cooling down.
Dynamic stretching is advised both before and after a workout. Stretching should be performed after warming up and after cooling down.
The body of scientific evidence indicates that traditional, or static, stretching does not prevent injury. Experts now believe that dynamic stretching, on the other hand, can increase flexibility and may help prevent injury when performed before and after exercise.
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