Dynamic Stretching

1. Dynamic Stretching

2. Objectives • Discuss the different advantages/disadvantages of ballistic, static and dynamic stretching • Determine what type of stretching is most appropriate for different sports • Demonstrate proper mechanics with dynamic stretches • Design a sport-specific warm-up for each sport • Discuss importance of cool-down stretching • Have fun!

3. Effects of Stretching • Acute Effects • Elongating the elastic component of the musculotendinous unit • Improving blood flow • Chronic Effects • Adding sarcomeres • Lengthen shortened tissues • Decrease muscle/joint stiffness

4. Types of Stretching Activities • Static Stretching • Ballistic Stretching • Dynamic Stretching • Proprioceptive Neuromuscular Facilitation Stretching

5. Static Stretching • The muscles and connective tissue being stretched are held in a stationary position at their greatest possible length for some period. • Held a minimum of 15-30 seconds 1 2 3 • Maintain good limb alignment • Advantages • Less overall force (decreases danger of exceeding tissue extensibility limits)‏ • Lower energy requirements • Lower likelihood of muscle soreness 4 • Less effect on Ia and II spindle afferent fibers • Disadvantages • May weaken muscles for up to 30 minutes following • Easy to compensate

6. Ballistic Stretching • Uses quick movements that impose a change in length of muscle or connective tissue • Appear to be jerky in nature • Advantages • Assist in preparing for plyometric activities • Can increase long-term flexibility in athletes • Disadvantages • Greater chance of muscle soreness and injury • Excessive uncontrolled forces • Proposed neurologic inhibitory influences associated with rapid-type stretching 5-7, 8, 9, 10, 11

7. PNF Stretching • Capitalize on the use of the neurophysiologic concept of stretch activation • Contract-relax (CR) sequence, agonist contraction (AC) or contract-relax-agonist contraction (CRAC)‏ • Works by activating the Golgi Tendon Organ, inhibiting the muscle being stretched, and using the principle of reciprocal inhibition 15 • Advantage: Can work well on stubborn muscles • Disadvantage: Requires therapist with constant communication

8. Dynamic Stretching • Somewhat similar to ballistic stretching • Instead of bouncing, has repeated motions through full-range • Recent evidence in the literature suggests this is the best warm-up for athletes 12, 13, 14

9. 15 male, 15 female college PE majors One-repetition maximum (1RM) lift of prone knee flexion and seated knee extension tested Two treatments: 10 minutes of quiet sitting (NS) or 20 minutes of passive static stretching of hip, thigh, and calf groups (ST) ST group demonstrated 16% improvement in flexibility in sit-and-reach test 8.1% decrease in 1RM of knee flexors and extensors Recommend avoiding intense static stretching prior to any event in which success is related to maximal strength output ACUTE MUSCLE STRETCHING INHIBITS MAXIMAL STRENGTH PERFORMANCEKokkonen, Nelson, Cornwell –Res. Q. Exercise Sport, 1998, 69, 411-415

10. 8 subjects used as own controls Both legs subjected to same warm-up and stretching treatments, then one leg exposed to active recovery (experimental treatment) and other leg recovered passively (control) Knee extensor single leg maximal voluntary contraction (MVC) measured at baseline, post-stretching, and post-recovery MVC baseline strength of control and treated legs decreased post-stretching by 8.0% and 8.9%. MVC baseline strength further decreased post-recovery by 1.3% and 1.2% Results confirm significant strength is lost post-stretching. Results fail to show greater improvement in strength in active vs passive recovery Indicate that muscular exercises during poststretching period are unlikely to minimize stretch-induced strength deficits EFFECT OF ACTIVE RECOVERY ON ACUTE STRENGTHDEFICITS INDUCED BY PASSIVE STRETCHINGViale, Nana-Ibrahim, and Martin -Journal of Strength and Conditioning Research, 2007, 21(4), 1233–1237

11. ACUTE EFFECT OF STATIC AND PROPRIOCEPTIVE NEUROMUSCULAR FACILITATION STRETCHING ON MUSCLE STRENGTH AND POWER OUTPUT Marek, et al –Journal of Athletic Training 2005; 40(2): 94-103 • Static and PNF stretching reduced peak torque, mean power output, and EMG amplitute of vastus lateralis and rectus femoris muscles at both slow and fast velocities • AROM and PROM increased as a result of static and PNF stretching • Practitioners need to consider the risk-to-benefit ratio when incorporating static or PNF stretching

12. 18 professional soccer players from English Premier League 3 different warm-up protocols tested Static Stretching No Stretching Dynamic Stretching 4 outcomes measured Vertical Jump 10-meter Acceleration 20-meter Maximal Speed Zig-Zag Agility No difference between static and no stretch in vertical jump, 10-meter acceleration, or zig-zag agility Static stretching better than no stretching in 20-meter maximal speed Dynamic stretching superior to both no stretching and static stretching in 3 of 4 outcomes Concluded that dynamic stretching is probably most effective as preparation for the high-speed performances required in sports such as soccer EFFECTS OF DIFFERENTIAL STRETCHING PROTOCOLSDURING WARM-UPS ON HIGH-SPEED MOTORCAPACITIES IN PROFESSIONAL SOCCER PLAYERSLittle and Williams -Journal of Strength and Conditioning Research, 2006, 20(1), 203–207

13. Experiment 1: knee-flexion strength endurance exercise measured at 60% and 40% body weight following either no-stretching or stretching regimen Stretching significantly reduced muscle strength endurance by 24% at 60% body weight and by 9% at 40% body weight Experiment 2: knee flexion muscle strength endurance test performed at 50% body weight on 4 different days, with 2 tests following a no-stretch regimen and 2 tests following a stretching regimen Stretching significantly reduced muscle strength endurance by 28% ACUTE MUSCLE STRETCHING INHIBITS MUSCLE STRENGTH ENDURANCE PERFORMANCENelson, Kokkonen, Arnall -Journal of Strength and Conditioning Research, 2005, 19(2), 338-43 Recommend avoiding stretching prior to any activity where endurance is needed.

14. THE EFFECT OF STATIC STRETCHING ON PHASES OF SPRINT PERFORMANCE IN ELITE SOCCER PLAYERSSayers, Farley, Fuller, Jubenville, Caputo -J Strength Cond Res, 2008, 22(5), 1416-21 • 20 elite female soccer players • Randomly assigned to stretch or no-stretch • Looked at acceleration, maximal-velocity sprint time, and overall sprint time between stretch and no-stretch conditions • Static stretching produces negative effect on sprint performance and should not be included as part of preparation routine for physical activity that requires sprinting

15. Retention • 2-4 weeks after a 6 week stretching program 16‏ • 3-5x / week can produce GAINS • 1x / week may be sufficient to MAINTAIN • May need to be part of daily routine for someone with significant deficits • Should be able to address your needs/modify as needed (previous surgery, long-term disease, upcoming race, etc)‏

16. How long??? • One 30-second stretch is enough to decrease strength by 5.4% • Six 30-second stretches are enough to decrease strength by 12.4% A single 30-s stretch is sufficient to inhibit maximal voluntary strength. Winchester, Nelson, Kokkonen. Res Q Exerc Sport. 2009 Jun; 80(2): 257-61

17. Summary • Static stretching may make better cool-down in sports that involve maximum strength, endurance, sprinting, etc. • Dynamic stretching may make better warm-up • Be Functional • Flexibility is still important part of overall athleticism and treatment • Have fun!

18. References 1. Bandy WD, Irion JM. The effect of time of static stretch on the flexibility of the hamstring muscles. Phys Ther 1994; 74:845-852. 2. Lentell G, Hetherington T, Eagan J, et al. The use of thermal agents to influence the effectiveness of a low-load prolonged stretch. J Orthop Sports Phys Ther. 1992; 5: 200-207. 3. Madding SW, Wong JG, Hallum A, et al. Effects of duration of passive stretching on hip abduction range of motion. J Orthop Sports Phys Ther. 1987; 8:409-416. 4. deVries HA. Evaluation of static stretching procedures for improvement of flexibility. Res Q. 1962; 33:222-229. 5. Entyre BR, Abraham LD. Antagonist muscle activity during stretching: a paradox reassessed. Med Sci Sports Exerc. 1988; 20:285-99. 6. Entyre BR, Abraham LD. Ache-reflex changes during static stretching and two variations of PNF techniques. Electroencephalogr Clin Neurophysiol. 1986; 63:174-179. 7. Entyre BR, Lee EJ. Chronic and acute flexibility of men and women using three different stretching techniques. Res Q. 1988; 222:228. 8. Moore M, Hutton R. Electromyelographic investigation of muscle stretching techniques. Med Sci Sports Exerc. 1980; 12:322-329. 9. Shindo M, Harayama H. Kondo K, et al. Changes in reciprocal Ia inhibition during voluntary contraction in man. Exp Brain Res. 1984; 53:400-408. 10. Zachazewski JE. Flexibility for sport. In: Sanders B, ed Sports Physical Therapy. Norwalk, CT: Appleton & Lange, 1990. 11. Zachazewski JE. Improving flexibility. In: Scully RM, Barnes MR, eds. Physical Therapy. Philadelphia: J.B. Lippincott; 1989. 12. Herman SL and Smith DT. Four-Week dynamic stretching warm-up intervention elicits longer-term performance benefits. J Strength and Cond Res. 2008; 22(4): 1286-1297. 13. Viale F, Nana-Ibrahim S, and Martin RJF. Effect of Active Recovery on Acute Strength Deficits Induced by Passive Stretching. J Strength and Cond Res; 2007; 21(4):1233-1237. 14. Little T and Williams AG. Effects of differential stretching protocols during warm-ups on high-speed motor capacities in professional soccer players. J Strength and Cond Res. 2006; 20(1): 203-207. 15. Hutton RS. Neuromuscular basis of stretching exercises. In: Komi PV, ed. Strength and Power in Sports. Boston: Blackwell Scientific; 1992:29-38. 16. Zebas CJ, Rivera ML. Retention of flexibility in selected joints after cessation of a stretching exercise program. In : Dotson CO, Humphrey JH, eds: Exercise Physiology: Current Selected Research Topics. New York: AMS Press; 1985.