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  1. Stretching Katelyn Bennett David Berning Fall 2005

  2. Introduction • There are many theories and myths about the importance and effect of stretching. • Coaches tend to put a lot of emphasis on stretching prior to and following activity. • Lately there has been controversy on the effectiveness of stretching. Don’t forget to stretch!

  3. Questions about Stretching • What type of stretching is best? • How long should we stretch? • Does stretching prevent injury? • Does stretching improve performance?

  4. Types of Stretching • Static stretching • Holding a stretching exercise in one position without movement • The stretch is taken to the point where resistance is felt but no pain. • Dynamic stretching • Stretching movements that use muscle power to move muscle through full ROM. • Examples: neck rolls, arm circles, knee rotations • Proprioceptive Neuromuscular Facilitation (PNF) • Combination of static passive stretching and isometric stretching • Most common PNF stretching technique is the contract-relax method

  5. Static Stretching • Improves ROM [Nelson et al] • Impairs warm-up effect [Behm et al] • Decreases balance • Slows muscle activation for about an hour [Fowles et al] • Decreases peak torque [Power et al] • Possibly due to altered length-tension relationship or a CNS inhibitory • Impairs maximal force production [Cramer et al]

  6. Comparison between Stretching Types • Static stretching better than PNF [Davis et al] • PNF is more effective post-exercise than before exercise [Funk et al] • 30 seconds of static stretch is better than dynamic for hamstring flexibility [Bandy et al.] • Static stretching slows muscle activation; dynamic stretching is a better choice before competition [Fowles et al] • Results are varied and require more research to determine best mode of stretching

  7. Duration Study • 5 week study of static hamstring stretching; comparing 30s, 60s, 90s, 120s • 30 seconds best; longer didn’t provide more benefit • Effect of 15 minutes of contract-relax stretching on ROM on lower extremities [moller et al.] • Significant increase in hip abduction (+17%), knee flexion (+4%), ankle dorsiflexion w/ knee flexed (+18%), and ankle dorsiflexion w/ knee straight (+16%)

  8. Duration of Stretching • Holding stretch for 30 seconds is sufficient to increase ROM [Bandy et al, Ford et al] • No change in ROM by increasing duration of stretch to 30-60 seconds [Bandy et al] • Stretching once a day is just as effective as stretching three times a day • Total of 15 minutes of stretching for all muscle groups recommended [Moller et al]

  9. Effect of Stretching on Performance • Static stretching decrease muscle strength endurance [Nelson et al] • Recommended that heavy static stretching be avoided prior to performance requiring maximal muscle strength endurance • Neither static nor ballistic stretching had an effect on vertical jump [Unick et al.] • Pre-event stretching negatively impacts high power, short term exercise (example: 20 meter sprints) [Nelson et al]

  10. Stretching andInjury Prevention • There is not sufficient evidence to endorse or discontinue routine stretching before or after exercise to prevent injury in athletes [Thacker et al] • Decreased incidence of muscle-related injury, but doesn’t prevent bone or joint damage (total injury rate is approximately the same) [Amako et al] • Stretching may help aid in prevention of stress fractures [Sanderlin et al] • Stretching necessary for sports with high intensity SSC’s to stretch the muscle-tendon unit (soccer, football) [Witvrouw et al] • Stretching unnecessary for sports containing limited SSC’s (jogging, cycling, swimming) [Herbert te al]

  11. Reasons Stretching does not Prevent Injury • No basic science research shows that an increase in muscle compliance is associated with increased ability to absorb energy [Shrier et al] • Most injuries occur eccentrically, within normal ROM [Shrier et al] • Even mild stretching can cause damage at the cytoskeletal level [Shrier et al] • No effect on activities in which excessive muscle length is not an issue [Shrier et al] • Stretching increases pain tolerance, which is not good [Shrier et al]

  12. Conclusion • Results from several studies contradicted one another. • Research is still needed to make definite conclusions about the best type of stretching and effects of stretching on injury and performance. • Since there is no clear cut answer, the decision about how or when to stretch is up to you!

  13. References • Behm, D G. "Effect of acute static stretching on force, balance, reaction time, and movement time." Medicine and Science in Sports and Exercise (2004). • Brandy, W D., J M. Irion, and M Briggler. "The effect of static stretch and dynamic range of motion training on flexibility of the hanstring muscles." Journal of Orthopedic Sports Physical Therapy (1998). • Cramer, J T. "Acute effects of static stretching on peak torque in women." Journal of Strength and Conditioning Research (2004). • Davis, D. S., and Paul E. Ashby. "The effectiveness of 3 srtetching techniques on hamstring flexibility using consistent stretching parameters." Journal of Strength and Conditioning Research (2005). • Ford, Gregory S., Margaret A. Mazzone, and Keith Taylor. "The effect of 4 different durations of static hamstring stretching on passive knee-extension range of motion." Journal of Sport Rehabilitation (2005). • Funk, Daniel C., and Ann M. Swank. "Impact of Prior Exercise on Hamstring Flexibility: A Comparison of Proprioceptive Neuromuscular Facilitation and Static Stretching." Journal of Strength and Conditioning Research. • Moller, M, J Ekstrand, and B Oberg. "Duration of stretching effect on range of motion in lower extremities." Arch Phys Med Rehabil (1985). • Nelson, Arnold G., Joke Korronen, and David A. Arnall. "Acute Muscle Stretching Inhibits Muscle Strength Endurance Performance." Journal of Strength and Conditioning Research (2005). • Nelson, Arnold G., Nicole M. Driscoll, and Dennis K. Landin. "Acute effects of passive muscle stretching on sprint performance." Journal of Sports

  14. References • Sciences (2005). • Nelson, R T. "Eccentric training and static stretching improve hamstring flexibility of high school males." Journal of Athletic Training (2004). • Power, K. "An acute bout of static stretching: effects on force and jumping performance." Medicine and Science in Sports and Exercise (2004). • Roberts, Jennifer M., and Karen Wilson. "Effect of stretching duration on active and passive range of motion in the lower extremity." British Journal of Sports Medicine (1999). • Shrier, Ian. "When and Whom to Stretch?" Physician and Sportsmedicine (2005). • Unick, Jessica, Scott Kieffer, Wendy Cheesman, and Anna Feeney. "The Acute Effects of Static and Ballistic Stretching on Vertical Jump Performance in Trained Women." Journal of Strength and Conditioning Research (2005). • Wiemann, K, and K Hahn. "Influences of strength, streching acid circulatory exercises on flexibility parameters of the human hamstrings." Occupational Health and Industrial Medicine (1997). • Yamaguchi, Taichi, and Kojiro Ishii. "Effects of Static Stretching for 30 Seconds and Dynamic Stretching on Leg Extension Power." Journal of Strength and Conditioning Research. • Amako, M, and T Oda. "Effect of static stretching on prevention of injuries for military recruits." Mil Med (2003). • Herbert, Rob D. "Effects of stretching before and after exercising on muscle soreness and risk of injury: systematic review." British Journal

  15. References • of Sports Medicine (2002). • Pettineo, S J. "Female ACL injury prevention with a functional integration exercise model." Strength and Conditioning journal (2004). • Shrier, Ian. "Stretching before exercise: an evidence based approach." British Journal of Sports Medicine (2000). • Shrier, Ian. "Stretching before exercise does not reduce the risk of local muscle injury: a critical review of the clinical and basic science literature." Clinical Journal of Sports Medicine (1999). • Thacker, S B., and J Gilchrist. "The impact of stretching on sports injury risk: a systematic review of the literature." Medicine and Science in Sports and Exercise (2004). • Witvrouw, Erik. "Stretching and Injury Prevention." Sports Medicine (2004). • • •