Stretch Yourself

Stretching and Injuries

by Thomas Kurz, author of Stretching Scientifically, Secrets of Stretching, Science of Sports Training, and co-author of Basic Instincts of Self-Defense.

This is the ninth installment of my column on training that appeared in July 2000 issue of TaeKwonDo Times.

To read the previous installment click here.

In this issue I will address two misconceptions: That having great flexibility always prevents injuries, or that stretching before activity will.

Well, a muscle does not have to be maximally stretched to be torn. Muscle tears often are the result of a special combination of a stretch and a contraction at the same time and neither the stretch nor the contraction has to be maximal. Sometimes the contraction is really a spasm, resulting from a chronic weakness of the muscle. Even the most flexible athlete can develop an overuse injury that manifests itself as a muscle spasm. If the athlete continues to exercise with a muscle spasm, eventually a strong tension of the affected muscle may (and often does) tear it. So you see that great flexibility alone will not prevent injuries.

If muscles of one limb or side of the body are more tensed than muscles on the other side, you may have a nerve problem or misaligned bones. For example, a twisted pelvis will cause one hamstring to be more tensed than the other. Stretching overly tensed muscles cannot fix the cause of their abnormal tension. In this example, it neither realigns the pelvis nor addresses the cause of this misalignment, which can be neurological or mechanical. While stretching may make you temporarily feel better, it will not remove a potential cause of injury. This is why stretching, and especially static stretching, before working out does not prevent injuries.

Moreover, for several seconds following any type of static stretch you cannot display your top agility or maximal speed because your muscles are less responsive to stimulation—your coordination is off. Static stretches reduce the force production of the stretched muscles. This was shown by several studies. Subjecting calf muscles to several 30-second stretches reduces their force afterwards (Rosenbaum and Hennig 1995). Three 15-second stretches of the hamstrings, quadriceps, and calf muscles reduced the peak vertical velocity of a vertical jump in the majority of subjects (Knudson et al. 2000). Maximal force production is impaired for several minutes after strenuous static stretching. Kokkonen et al. (1998) showed that maximal force in knee flexion declined on the average by 7.3% and in knee extension by 8.1% after static stretching even though 10–15 minutes passed between stretching and the strength test. Wilson (1994, quoted by Kokkonen et al. 1998) showed that maximal force production in a bench press is positively related to the stiffness of the prime movers (coracobrachialis, deltoid, pectoralis major, pectoralis minor, serratus anterior, triceps brachii), so stretching them could affect it adversely.

If you try to make a fast, dynamic movement immediately after a static stretch, you may injure the stretched muscles. (This caution applies to a single workout and not to long-term training. Long-term stretching programs lasting 3–12 weeks do improve the strength of knee flexors according to Dintiman 1964, Kokkonen et al. 1995, Worrel et al. 1994; all quoted by Kokkonen et al. 1998.)

Doing static stretches before a workout that consists of dynamic actions is counterproductive. The goals of the warm-up are: an increased alertness, improved coordination, improved elasticity and contractibility of muscles, and greater efficiency of the respiratory and cardiovascular systems. Static stretches, isometric or relaxed, just do not fit in a warm-up. Isometric tensions will only tire you and decrease your coordination. Passive, relaxed stretches, on the other hand, have a calming effect and can even make you sleepy.

So what can prevent injuries?

Rational strength training that balances strength of opposing muscle groups, for one (provided you do not have those misalignment problems as previously described). Research shows that great differences in strength between two opposing muscle groups, for example, having a hamstring-quadriceps ratio lower than 61%, as well as a strength imbalance of 8–10% between right and left hamstrings, are the main causes of hamstring injuries (Orchard et al. 1997, Burkett 1970).

In case of excessive tension (excessive neural stimulation) or weakness (excessive neural inhibition) caused by misaligned joints or neurological problems, typical strength training exercises will not help either. Typical strength exercises will either overstress the overly tensed muscles or will bypass the weak ones by recruiting others to do their job. To fix such problems you need the help of an applied kinesiology specialist who, among other modes of treatment, may prescribe special exercises for normalizing the tension of muscles.

Another way of preventing injuries is learning the efficient form of movements. Eliminate those moments in your techniques in which you use the sudden tension of already stretched muscles to counter the fast movement of a relatively big mass. Such tensions may lead to tears in the muscles of a supporting leg in kicking, for example. A good technique feels effortless. Practice the correct technique and develop a habit of throwing your techniques only when the distance is right to keep yourself from straining your muscles.

There are many other causes of injuries ranging from the wrong exercises to such factors as an improper exercise surface (floor too stiff, mat too soft), temperature, humidity, ventilation, and gym lighting (big contrasts in illumination and colors can cause difficulties in estimating space relationships). I will discuss these other causes of injuries in future articles.

In the next column I will answer typical questions on injuries, their causes and treatments.

To read the next installment of this column click here.

This article is based on the book Stretching Scientifically. Get this book now and have all of the info—not just the crumbs! Order now!

References

Burkett, L. N. 1970. Causative factors in hamstring strains. Medicine and Science in Sports vol. 2, no. 1 (Spring), pp. 39–42.

Knudson, D., K. Bennet, R. Corn, D. Leick, and C. Smith. 2000. Acute Effects of Stretching Are Not Evident in the Kinematics of the Vertical Jump. Research Quarterly for Exercise and Sport vol. 71, no. 1 (Supplement), p. A-30.

Kokkonen, J., A. G. Nelson, and A. Cornwell. 1998. Acute muscle stretching inhibits maximal strength performance. Research Quarterly for Exercise and Sport vol. 69, no. 4, pp. 411–5.

Orchard, J., J. Marsden, S. Lord, and D. Garlick. 1997. Preseason hamstring muscle weakness associated with hamstring muscle injury in Australian footballers. American Journal of Sports Medicine vol. 25, no. 1 (Jan-Feb), pp. 81–5

Rosenbaum, D. and E. M. Hennig. 1995. The influence of stretching and warm-up exercises on Achilles tendon reflex activity. Journal of Sport Sciences vol. 13, no. 6, pp. 481–90.

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