|Commissioned Corps E-Bulletin|
Submitted by LCDR Scott McGrew
As you prepare for fitness testing, don’t forget that flexibility training is an important part of your exercise program. Stretching provides increased joint range of motion and improved joint mechanics necessary for maximum performance. There is, however, some controversy about when and how to stretch (Quinn, 2010).
Most adults were trained in school to do prolonged stretching just prior to athletic events. However, some recent research actually points to decreased performance and increased risk of injury when stretching prior to exercise. Current studies indicate that doing a brisk warm-up that includes mild dynamic stretching decreases the risk of injury. So if injury prevention is the primary objective, the evidence suggests that athletes should limit stretching before exercise and increase warm up time
Studies do support that range of motion can be increased by a single 15-30 second stretch for each muscle group per day. However, some people require a longer duration or more repetitions. Research also supports the idea that the optimal duration and frequency for stretching may vary by muscle group (ACSM, 2006).
The long-term effects of stretching on range of motion show that after 6 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. Another 6-week study 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 30-second stretches as part of general conditioning to improve range of motion.
There are several types of stretches one may incorporate into their fitness training. The following information provides an overview of stretching variations that you can read more about in the resources and references noted at the end of this article:
Stretching should be done after you are done exercising while your muscles are still warm. Hold a given stretch until you feel a moderate pulling in the muscle, but no pain. As you hold the stretch, the muscle will relax. As you feel less tension you can increase the stretch again until you feel the same moderate pull. Hold your stretch for 30 seconds. 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) (Quinn, 2010).
What Stretch is Best?
In general, research indicates that PNF stretching results in greater increases in range of motion compared with static or ballistic stretching. 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 when re-stretched quickly following a short relaxation period. Such eccentric contractions are believed to increase the risk of injury (Quinn, 2010).
For more information on stretching, check out the following sites:
ACSM. 2006. ACSM’s Guidelines for Exercise Testing and Prescription (7th ed.). Philadelphia: Lippincott Williams & Wilkins.
Andersen, J.C. 2006. Flexibility in performance: Foundational concepts and practical issues. Athletic Therapy Today, 11 (3), 9–12.
Kravitz, Len. “Stretching--A Research Retrospective.” Fitness Journal. November 2009. Web. 28 Dec. 2010
Quinn, Elizabeth. “When to Stretch – Why Experts Recommend Athletes Stretch After Exercise.” About.Com. June 04, 2010. Web. 29 Dec 2010
Sharman, M. J., Cresswell, A. G. and Riek, S. (2006) Proprioceptive neuromuscular facilitation stretching - Mechanisms and clinical implications. Sports Medicine, 36 11: 929-939.
Thacker, Stephen B. et al. "The Impact of Stretching on Sports Injury Risk: A Systematic Review of the Literature." Medicine & Science in Sports & Exercise. 36(3):371-378, March 2004.
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