Many athletes have been told to stretch before starting a workout, as such a routine prepares the body for physical exertion. But new evidence suggests that stretching before a workout may do more harm than good.
Several studies now indicate that static stretching, or slowly moving muscles until they start to hurt and then holding the position, may impair strength and speed. One study published in the April 2013 Journal of Strength and Conditioning Research concluded that those who stretch before lifting weights could find themselves feeling wobblier and weaker than expected. Another study at the University of Zagreb in Croatia reviewed 104 studies of people who practiced static stretching as a warm-up. Muscle strength was reduced by more than 5 percent in those who stretched. Another study examined men who did basic squats while lifting barbells. Men who stretched and those who didn't were examined. Those who stretched lifted 8.3 percent less weight than those who skipped stretching.
Many personal trainers now discourage extensive stretching before a workout, feeling that stretching post-workout provides the most benefit. A number of people have long confused stretching with warming up muscles, but static stretching is a different activity from actual muscle warmup, which generally involves low-impact movement of the body. There is no evidence that stretching before a workout makes muscles more limber or reduces the risk of injury during a workout.
Some experts liken stretching muscles prior to working out to overstretching a rubber band. The muscles may get limp and overworked prematurely and then not be able to perform to peak when power intensity is needed. Others argue that when people engage in stretching, the muscles are actually tightening, rather than relaxing, which may make athletes more prone to injury.
Stretching improves flexibility and range of movement. But some fitness experts suggest stretching be reserved for times when exercise will not immediately follow, such as after a workout has been completed.