Reading for Control of Human Movement 2:
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Disadvantage of stretching
Prescription of exercise to increase flexibility
Physiology of stretching
Types of stretching
Changes in muscle length after stretching
Static elongation for 10 to 30 second at a range that causes mild discomfort enhances flexibility. Longer durations of elongation produce insignificant benefits. Tissue elongation changes does not change significantly after the first four repetitions. Slow rates of elongation permit greater stress relaxation than faster rates of elongation and produce generate lower tissue forces (Borms, VanRoy, Santens, & Haentjens, 1987; Taylor, Dalton, Seaber, & Garrett, 1990; Bandy & Irion, 1994; Lamontagne, Malouin, & Richards, 1997).
Dynamic stretching for 30 seconds (6 repetitions of 5 second stretches) increased ROM, but not as much as a 30-second static stretch (Bandy, Irion, & Briggler, 1998).
For example, you will practice two PNF techniques in a lab that addresses stretching or elongating a muscle. During a the isometric phase of a "hold-relax" maneuver, Golgi tendon organs (GTO), located in the muscle's myotendinous junction, are presumably stimulated so that they produce reflex inhibition; this prevents muscle action from interfering with the ensuing passive stretch.
GTOs are theoretically stimulated during the isometric phase of the "slow-reversal hold relax" maneuver as well. Additionally, the "slow reversal" phase, during which the antagonist acts concentrically, elongates the agonist or target muscle. The elongation activates spindles within the target muscle. A PNF-based explanation for the slow-reversal technique's effectiveness is that the elicited spindle activity desensitizes the spindles so they fail to produce a stretch reflex during the subsequent phase of passive elongation. Were it not for this theoretical desensitization, activity in the muscle's spindles would enhance a stretch reflex that resists elongation.
Students can review information on muscle spindles and Golgi tendon organs at a useful web site maintained by Northeastern University's PT department
For certain contractures, the required duration of stretching is considerable. Tardieu, Lespargot, Tabary, and Bret (1988) address the reduction of contractures in children with cerebral palsy and conclude "...there was no progressive contracture when the soleus was stretched for at least six hours a day (the same time as in non-handicapped children). On the other hand, there was progressive contracture when the stretching time was as short as two hours" a day.
Even in patients without neurological problems, the effects of stretching on increasing soft tissue length are transient. Magnusson (1988) reviewed the literature and found "with repeated stretches muscle stiffness declined, but returned to baseline values within 1 hour. Long-term stretching (3 weeks) increased joint range of motion as a result of a change in stretch tolerance rather than in the passive properties."
Bandy, W. D., & Irion, J.M. (1994). The effect of time on static stretch on the flexibility of the hamstring muscle. Physical Therapy, 74, 845-852.
Bandy, W.D., Irion, J.M., & Briggler, M. (1998). The effect of static stretch and dynamic range of motion training on the flexibility of the hamstring muscles. Journal of Orthopedic and Sports Physical Therapy, 27, 295-300.
Borms, J., VanRoy, P., Santens, J.P., & Haentjens, A. (1987). Optimal duration of static stretching exercises for improvement of coxofemoral flexibility. Journal of Sports Science, 5, 39-47.
Crisco, J.J., Chelikani, S., Brown, R.K., & Wolfe, S.W. (1997). The effects of exercise on ligamentous stiffness in the wrist. Journal of Hand Surgery [Am], 22, 44-8.
Knott, M., & Voss, D.E. (1968). Proprioceptive neuromuscular facilitation: Patterns and techniques. (2nd ed.). Philadelphia: Harper and Row.
Lamontagne, A., Malouin, F., & Richards, C.L. (1997). Viscoelastic behavior of plantar flexor muscle-tendon unit at rest. Journal of Orthopedic and Sports Physical Therapy, 26, 244-52.
Magnusson, S.P. (1998). Passive properties of human skeletal muscle during stretch maneuvers: A review. Scandinavian Journal of Medicine & Science in Sports, 8, 65-77.
McHugh, M.P., Connolly, D.A., Eston, R.G., Kremenic, I.J., Nicholas, S.J., & Gleim, G.W. (1999). The role of passive muscle stiffness in symptoms of exercise-induced muscle damage. American Journal of Sports Medicine, 27, 594-9.
Sady, S. P., Wortman, M., & Blanke, D. (1982). Flexibility training: Ballistic, static or proprioceptive neuromuscular facilitation? Archives of Physical Medicine and Rehabilitation, 63, 261-263.
Tardieu, C., Lespargot, A., Tabary, C., & Bret M.D. (1988). For how long must the soleus muscle be stretched each day to prevent contracture? Developmental Medicine & Child Neurology, 30, 3-10.
Taylor, D. C., J. D. Dalton, A. V. Seaber, & W. E. Garrett. (1990). Viscoelastic properties of muscle-tendon units: The biomechanical effects of stretching. American Journal of Sports Medicine, 18, 300-309.
Voss, D.E. (1967). Proprioceptive neuromuscular facilitation. American Journal of Physical Medicine, 46, 838-99.
Wilson, G.J., Elliott, B.C., & Wood, G.A. (1992). Stretch shorten cycle performance enhancement through flexibility training. Medicine & Science in Sports & Exercise, 24, 116-123.