Evlo Fitness/Education/Fitness Myths/Is stretching really beneficial? If and when you should stretch, according to research.
04/16/2020
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Shannon Ritchey
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Is stretching really beneficial? If and when you should stretch, according to research.

Stretching has been generally accepted as a vital piece of an exercise routine, but recently, many health professionals have questioned its benefits. I wanted to dive into the current research to determine a guide that the average fitness enthusiast could implement. 

I discovered the research on the benefits and effects of stretching is contradictory, largely inconclusive, and unclear.  This indicates we should be taking a closer look at stretching, how we dose it, how to incorporate it into an exercise routine, or if we should be doing it at all. I sifted through many contradictory systematic reviews about stretching, and many of my questions were left unanswered. There is also lacking research on the long-term effects of stretching. 

Here are the major takeaways from my review: 

  1. Muscles do not stretch. Most studies agree that stretching improves flexibility by manipulating your nervous system’s ability to tolerate a certain position. 
  2. There is a good chance static stretching temporarily decreases strength and performance. Short bouts of stretching a single muscle (less than 15 seconds) before exercise probably won’t have a significant effect on that muscle’s strength and performance. Dynamic warm-ups might be a safer route, as there is less likelihood of dynamic movement decreasing strength.
  3. Static stretching might not be as effective in improving flexibility when held for shorter than 15 seconds but could decrease strength when held for longer than 15 seconds. 
  4. There is no conclusive evidence that suggests for or against the benefits of stretching regularly. 

I’d like to provide clarity around some terms I will be discussing.

1. Flexibility is generally accepted as the end range of motion that is available in a joint, given the structure surrounding the joint (bones, tendons, ligaments, muscles, and other tissues). Flexibility is usually assessed passively (moving the joint without active muscular contraction, like pulling your leg closer to your chest, or using your body weight to push a joint further.)  

2. Mobility is the ability of the tissues surrounding a joint to contract and move the joint.

Two things largely control both flexibility and mobility: 

  1. Your nervous system’s ability to contract and relax muscles
  2. The structure of your joints 
    1. The shape of bones, the presence of osteophytes, tears in cartilage, etc. could all change the structure of the joint, thus affecting both its flexibility and mobility

There are many types of stretching, but this review will focus on static stretching. Static stretching involves holding a position near the end range of motion for a period of time (as short as 15 seconds, and as long as 10 minutes or longer). 

Here is a summary and conclusions I drew from the research on static stretching: 

  1. Should I static stretch before exercise? 
    1. Probably not, to be safe
      1. Many studies suggest stretching acutely decreases strength and endurance (9,11,12, 14, 15, 16, 17, 28). Still, one systematic review suggests stretching for less than 30 seconds might not decrease strength (18), but for longer than 60 seconds could reduce strength temporarily. Yet another study showed four sets of 30-second stretches decreases peak torque (14). Another suggests stretching for less than 45 seconds might not decrease strength (21). 
  2. Do I get more flexible from stretching?
    1. Yes (7, 25), but effects might be temporary (30 minutes) 
  3. Am I physically stretching the muscle? 
    1. Probably not
      1. Muscles and tendons are probably a fixed length and do not stretch beyond that length. Any increase in flexibility is probably due to an improved tolerance to that position rather than a mechanical change in the tissue (7, 26, 27). 
  4. Can stretching improve a contracture? 
    1. Probably not (6) 
  5. Can stretching reduce the risk of contracture? 
    1. Yes (6)
      1. According to this study, dynamic movement is just as effective (8)
  6. Can stretching before exercise be harmful?
    1. It can be 
      1. Along with the acute decreases in strength and performance (9,11,12, 14, 15, 17, 28), this systematic review suggests high-intensity stretches could increase the amount of inflammation in your tissues (23)
  7. How long of a stretch could reduce my performance before exercise?  
    1. Research is inconclusive
      1. Anywhere from 15 seconds – 60 seconds of stretching, of one muscle group could harm performance (13, 21, 18).
  8. Should I stretch during exercise (like on my breaks?)
    1. Probably not 
      1. As stated above, research is not clear on if it decreases strength, so it might not be worth the risk in between your sets 
  9. Does stretching after exercise reduce the risk of injury? 
    1. Probably not (2, 3, 24, 22)
  10. Does stretching reduce the risk of delayed onset muscle soreness? 
    1. Probably not (1, 4, 24)
  11. How long do I hold a stretch to improve my flexibility? 
    1. Longer than 15-30 seconds (26) 
  12. Is dynamic or static stretching more effective? 
    1. Studies are conflicting (27, 28), but both could be effective. 
  13. Does stretching provide functional improvements? 
    1. Inconclusive evidence  
      1. According to these two systematic reviews, stretching did not necessarily provide clinically meaningful outcomes (29, 30)
      2. This systematic review that only found studies of moderate to low quality suggested that stretching can provide lasting increases in range of motion (31) 

References

1. Shrier I. Stretching before exercise does not reduce the risk of local muscle injury: a critical review of the clinical and basic science literature. Clin J Sport Med. 1999;9. PubMed #10593217. ❐

 2. Herbert RD, Gabriel M. Effects of stretching before and after exercising on muscle soreness and risk of injury: systematic review. BMJ. 2002 Aug;325(7362):468. PainSci #57209. ❐

3. Pope RP, Herbert RD, Kirwan JD, et al. A randomized trial of preexercise stretching for prevention of lower-limb injury. Medicine Science in Sports Exercise. 2000 Feb;32(2):271–7. PubMed #10694106. ❐

4. Lund H, et al. The effect of passive stretching on delayed onset muscle soreness, and other detrimental effects following eccentric exercise. Scand J Med Sci Sports. 1998 Aug;8(4):216–21. PubMed #9764443. ❐

5. Radford JA, Landorf KB, Buchbinder R, Cook C. Effectiveness of calf muscle stretching for the short-term treatment of plantar heel pain: a randomised trial. BMC Musculoskelet Disord. 2007 Apr;8:36. PubMed #17442119. ❐ PainSci #52975. ❐

6. Harvey LA, Katalinic OM, Herbert RD, et al. Stretch for the treatment and prevention of contractures. Cochrane Database Syst Rev. 2017 Jan;1:CD007455. PubMed #28146605. ❐ PainSci #52742. ❐

7. Blazevich AJ, Cannavan D, Waugh CM, et al. Range of motion, neuromechanical, and architectural adaptations to plantar flexor stretch training in humans. J Appl Physiol (1985). 2014 Sep;117(5):452–62. PubMed #24947023. ❐

8. Williams PE, Catanese T, Lucey EG, Goldspink G. The importance of stretch and contractile activity in the prevention of connective tissue accumulation in muscle. J Anat. 1988 Jun;158:109–14. PubMed #3225214. ❐ PainSci #55291. ❐

9. Babault N, Kouassi BY, Desbrosses K. Acute effects of 15 min static or contract-relax stretching modalities on plantar flexors neuromuscular properties. J Sci Med Sport 13: 247–252, 2010.

10. Little T, Williams AG. Effects of differential stretching protocols during warm-ups on high-speed motor capacities in professional soccer players. J Strength Cond Res 20: 203–207, 2006.

11. Franco BL, Signorelli GR, Trajano GS, de Oliveira CG. Acute effects of different stretching exercises on muscular endurance. J Strength Cond Res 22: 1832–1837, 2008.

12. Janne Avela, Heikki Kyröläinen, and Paavo V. Komi. Altered reflex sensitivity after repeated and prolonged passive muscle stretching. 01 APR 1999

13. Beedle B, Rytter SJ, Healy RC, Ward TR. Pretesting static and dynamic stretching does not affect maximal strength. J Strength Cond Res 22: 1838–1843, 2008.

14. Cramer, JT, Housh, TJ, Johnson, GO, Miller, JM, Coburn, JW, and Beck, TW. Acute effects of static stretching on peak torque in women. J Strength Cond Res 18: 236-241, 2004.

15. Papadopoulos, G, Siatras, T, and Kellis, S. The effect of static and dynamic stretching exercises on the maximal isokinetic strength of the knee extensors and flexors. Isokinet Exerc Sci 13: 285-291, 2005.

16. Barroso R, Tricoli V, Santos Gil SD, Ugrinowitsch C, Roschel H. Maximal strength, number of repetitions, and total volume are differently affected by static-, ballistic-, and proprioceptive neuromuscular facilitation stretching. J Strength Cond Res. 2012;26:2432–2437.

17. Kay AD , Blazevich AJ . Moderate-duration static stretch reduces active and passive plantar flexor moment but not Achilles tendon stiffness or active muscle length. J Appl Physiol 106: 1249–1256, 2009. 

18. Kay AD, Blazevich AJ. Effect of acute static stretch on maximal muscle performance: A systematic review. Med Sci Sports Exerc. 2012;44:154–164.

19. Heisey CF, Kingsley JD. Effects of Static Stretching on Squat Performance in Division I Female Athletes. Int J Exerc Sci. 2016;9(3):359–367. Published 2016 Oct 1.

10. EFFECTS OF TWELVE-MONTH STRENGTH TRAINING SUBSEQUENT TO TWELVE-MONTH STRETCHING EXERCISE IN TREATMENT OF CHRONIC NECK PAIN JARI J. YLINEN, 1 ESA-PEKKA TAKALA, 2 MATTI J

21. Stathokostas L, Little RM, Vandervoort AA, Paterson DH. Flexibility training and functional ability in older adults: a systematic review. J Aging Res. 2012;2012:306818. doi:10.1155/2012/306818

22. Rogan S, Wüst D, Schwitter T, Schmidtbleicher D. Static stretching of the hamstring muscle for injury prevention in football codes: a systematic review. Asian J Sports Med. 2013;4(1):1–9.

23. Apostolopoulos Nikos, Metsios George, Flouris Andreas, Koutedakis Yiannis, Wyon Matthew. The relevance of stretch intensity and position—a systematic review. Frontiers in Psychology. VOLUME=6   2015.

 24.  Herbert Rob D, Gabriel Michael. Effects of stretching before and after exercising on muscle soreness and risk of injury: systematic review BMJ 2002; 325 :468

25. Diulian M. Medeiros, Anelize Cini, Graciele Sbruzzi & Cláudia S. Lima (2016) Influence of static stretching on hamstring flexibility in healthy young adults: Systematic review and meta-analysis, Physiotherapy Theory and Practice, 32:6, 438-445, DOI: 10.1080/09593985.2016.1204401

26. Thacker SB , Gilchrist J , Stroup DF , Kimsey CD . The impact of stretching on sports injury risk: a systematic review of the literature. Med Sci Sports Exerc 36: 371–378, 200

27. Bandy, W. D., J. M. Irion, and M. Briggler. The effect of static stretch and dynamic range of motion training on the flexibility of the hamstring muscles. Phys. Ther. 27: 295–300, 1998.

28. Hortobagyi, T., J. Faludi, J. Tihanyi, and B. Merkely. Effects of intense “stretching”-flexibility training on the mechanical profile of the knee extensors and on the range of motion of the hip joint. Int. J. Sports Med. 6: 317–321, 1985.

29. Owen M. Katalinic, Lisa A. Harvey, Robert D. Herbert, Effectiveness of Stretch for the Treatment and Prevention of Contractures in People With Neurological Conditions: A Systematic Review, Physical Therapy, Volume 91, Issue 1, 1 January 2011, Pages 11–24, https://doi.org/10.2522/ptj.20100265

30. Radford JA, Burns J, Buchbinder R, et alDoes stretching increase ankle dorsiflexion range of motion? A systematic reviewBritish Journal of Sports Medicine 2006;40:870-875.

31. Harvey, L., Herbert, R. and Crosbie, J. (2002), Does stretching induce lasting increases in joint ROM? A systematic review. Physiother. Res. Int., 7: 1-13. doi:10.1002/pri.236