Studies on the benefits of stretching have yielded mixed results. A U.S. Army research team found that trainees with both the highest and lowest flexibility had the highest injury rates. They were, respectively, 2.2 and 2.5 times more likely to have an injury than trainees with average flexibility. 

Additionally, in a systematic review of  nearly 100 published medical studies on stretching and exercise, the authors found that stretching does increase flexibility, but this increased flexibility doesn't prevent injuries. They found injuries would be better prevented by warmups, strength training, and balance exercises than by stretching.
 
If you want to include stretching as part of your exercise routine, make sure you do it safely and effectively using proper technique. Stretching incorrectly can actually do more harm than good!
 
Use these tips to keep stretching safe:
 
1.  Don't stretch as a warm-up! You may hurt yourself if you stretch cold muscles. Before stretching, warm up with light walking, jogging, etc. at low intensity for five minutes.  If you're going to perform a specific activity, such as throwing a frisbee, do the move slowly and at low intensity at first to get your muscles used to it. Then speed up gradually as your muscles become accustomed to the motion.
 
2.  Strive for symmetry. Everyone is different, so rather than striving for the flexibility of a gymnast, focus on having equal flexibility side to side.
 
3.  Don't bounce. Stretch in a smooth movement without bouncing. Bouncing as you stretch can cause injury to your muscle.
 
4.  Don't stretch into pain. Expect to feel tension while you're stretching--not pain. If it hurts, you've pushed too far.
 
If you have an injury, you may need to adjust your stretching techniques. Also, don't think that because you stretch you can't get injured. Talk to your doctor or physical therapist about the most appropriate way to stretch if you have any health concerns.