Until recently, virtually all exercise books recommended pre-exercise stretching as part of warm-up. Training experts believed that stretching increased range of motion and lowered the risk of injury during the workout that followed.
This has changed. A number of studies have discovered that static stretching before exercise decreases power and strength, and could in fact increase the risk of injury.
Brazilian researchers found that static or ballistic stretching before weight training decreased strength endurance capacity during a weight-training program compared to a specific warm-up. This study was important since it showed that static stretching affects muscle endurance as well as strength and power.