The long-term effects of stretching on range of motion show that after six weeks, those who stretch for 30 seconds per muscle each day increased their range of motion much more than those who stretched 15 seconds per muscle each day. No additional increase was seen in the group that stretched for 60 seconds. Another 6 week study conducted found that one hamstring stretch of 30 seconds each day produced the same results as three stretches of 30 seconds. These studies support the use of thirty second stretches as part of general conditioning to improve range of motion.
Stretching Guidelines
To get the most from your stretching customize your routine to fit your needs. One way to do this is to stretch until you feel slight pulling but no pain. As you hold the stretch the muscle will relax. As you feel less tension you can increase the stretch again until they feel the same slight pull. Hold this position until you feel no further increase. If you do not seem to gain any range of motion using the above technique, you may consider holding the stretch longer (up to 60 seconds).
What Stretch is Best?
In general, Proprioceptive Neuromuscular Facilitation (PNF) stretching has resulted in greater increases in range of motion compared with static or ballistic stretching, though some results have not been statistically significant. Static stretches are a bit easier to do and appear to have good results. Studies indicate that continuous stretching without rest may be better than cyclic stretching (applying a stretch, relaxing, and reapplying the stretch), however some research shows no difference.
Most experts believe ballistic, or bouncing during a stretch, is dangerous because the muscle may reflexively contract if restretched quickly following a short relaxation period. Such eccentric contractions are believed to increase the risk of injury.
In addition to improving range of motion, stretching is extremely relaxing and most athletes use stretching exercises to maintain a balance in body mechanics. But one of the biggest benefits of stretching may be something the research can't quantify: it just feels good.
Source
Herbert RD, de Noronha M. Stretching to prevent or reduce muscle soreness after exercise. Cochrane Database of Systematic Reviews 2007, Issue 4.
Andersen, J. C. Stretching Before and After Exercise: Effect on Muscle Soreness and Injury Risk.
Journal of Athletic Training 40(2005): 218-220 Witvrouw, Erik, Nele Mahieu, Lieven Danneels, and Peter McNair. Stretching and Injury Prevention An Obscure Relationship. Sports Medicine 34.7(2004): 443-449
Ian Shrier MD, PhD and Kav Gossal MD. The Myths and Truths of Stretching: Individualized Recommendations for Healthy Muscles, The Physician and Sportsmedicine, VOL 28, #8, August 2000.
