Stretching credulity

Quick news-you-can-use today: the bulk of research shows that stretching before or after exercise doesn’t prevent injury or muscle soreness, or improve performance. In fact, stretching before exercise may increase the risk of injury.

And yes, you should warm up before exercise, but stretching is not a warm-up.

Woman enjoying a hamstring stretch while balanced on one leg (click to embiggen)
Stretching may feel great – and look impressive – but it won’t prevent injuries or improve athletic performance (Photo by lululemon athletica, via Wikimedia Commons)
Flexibility is one thing that stretching may help, although whether that has any benefits itself is not proven. Its popularity despite lack of evidence leads to the the following curious statement in the 2008 Physical Activity Guidelines for Americans (chapter 4):

“Flexibility is an important part of physical fitness… For this reason, flexibility activities are an appropriate part of a physical activity program, even though they have no known health benefits and it is unclear whether they reduce risk of injury.”

But one thing on which most of us would agree is that stretching feels good. That may be enough motivation itself – after all, it’s probably why animals do it. Just don’t expect other benefits.

For very thorough, exhaustive and well-written further reading, see Quite a Stretch, by Paul Ingraham.

More references after the jump…

As usual, these are presented in reverse chronological order, so you can read the most recent first.

1. Simic L, Sarabon N & Markovic G 2012, “Does pre-exercise static stretching inhibit maximal muscular performance? A meta-analytical review”, Scandinavian Journal of Medicine & Science in Sports, published online 8 Feb 2012, doi: 10.1111/j.1600-0838.2012.01444.x
“We applied a meta-analytical approach to derive a robust estimate of the acute effects of pre-exercise static stretching (SS) on strength, power, and explosive muscular performance… We conclude that the usage of SS as the sole activity during warm-up routine should generally be avoided.”

2. Kay AD & Blazevich AJ 2012, “Effect of acute static stretch on maximal muscle performance: a systematic review”, Medicine and Science in Sports and Exercise, vol. 44, no. 1, pp. 154-164, PMID: 21659901
“The benefits of preexercise muscle stretching have been recently questioned after reports of significant poststretch reductions in force and power production… Searches revealed 4559 possible articles… The detrimental effects of static stretch are mainly limited to longer durations (≥ 60 s), which may not be typically used during preexercise routines in clinical, healthy, or athletic populations. Shorter durations of stretch (<60 s) can be performed in a preexercise routine without compromising maximal muscle performance.”

3. Herbert RD, de Noronha M & Kamper SJ 2011, “Stretching to prevent or reduce muscle soreness after exercise”, Cochrane Database of Systematic Reviews 2011, issue 7, art. no. CD004577, DOI: 10.1002/14651858.CD004577.pub3
“The evidence from randomised studies suggests that muscle stretching, whether conducted before, after, or before and after exercise, does not produce clinically important reductions in delayed-onset muscle soreness in healthy adults.”

4. Yeung SS, Yeung EW & Gillespie LD 2011, “Interventions for preventing lower limb soft-tissue running injuries”, Cochrane Database of Systematic Reviews 2011, issue 7, art. no. CD001256, DOI: 10.1002/14651858.CD001256.pub2
“We found no evidence that stretching reduces lower limb soft-tissue injuries (6 trials; 5130 participants; risk ratio [RR] 0.85, 95% confidence interval [95% CI] 0.65 to 1.12). As with all non-significant results, this is compatible with either a reduction or an increase in soft-tissue injuries. We found no evidence to support a training regimen of conditioning exercises to improve strength, flexibility and coordination (one trial; 1020 participants; RR 1.20, 95% CI 0.77 to 1.87).”

5. Katalinic OM, Harvey LA, Herbert RD, Moseley AM, Lannin NA & Schurr K 2010, “Stretch for the treatment and prevention of contractures”, Cochrane Database of Systematic Reviews 2010, issue 9, art. no. CD007455, DOI: 10.1002/14651858.CD007455.pub2
“The review shows that stretch is not effective for the treatment and prevention of contractures… Contractures are characterised by the inability to move a joint freely. Contractures may be a complication of neurological conditions including stroke, spinal cord injury, traumatic brain injury and cerebral palsy.”

6. Wilson JM, Hornbuckle LM, Kim J-S, Ugrinowitsch C, Lee S-R, Zourdos MC, Sommer B & Panton LB 2010, “Effects of static stretching on energy cost and running endurance performance”, Journal of Strength & Conditioning Research, vol. 24, no. 9, pp. 2274-2279, doi: 10.1519/JSC.0b013e3181b22ad6
“Stretching before anaerobic events has resulted in declines in performance… This study investigated the effects of static stretching on energy cost and endurance performance in trained male runners. Ten trained male distance runners aged 25 ± 7 years with an average VO2max of 63.8 ± 2.8 ml/kg/min were recruited… Performance was significantly greater in the nonstretching (6.0 ± 1.1 km) vs. the stretching (5.8 ± 1.0 km) condition (p < 0.05… Our findings suggest that stretching before an endurance event may lower endurance performance and increase the energy cost of running.”

7. Goldman EF & Jones DE 2010, “Interventions for preventing hamstring injuries”, Cochrane Database of Systematic Reviews 2010, issue 1, art. no. CD006782, DOI: 10.1002/14651858.CD006782.pub2
“One small trial found that manual therapy (involving manipulation, massage and specific stretches to joints and muscles of the spine and leg) may prevent injuries of leg muscles, including the hamstrings. Three inconclusive trials tested interventions for preventing all leg injuries for which data for hamstring injury were available. Two trials found no evidence for an effect for balance training on a wobble board (proprioceptive protocol). One trial found no evidence for a warm up/cool down and stretching protocol for distance runners.”

8. Jamtvedt G, Herbert RD, Flottorp S, Odgaard-Jensen J, Håvelsrud K, Barratt A, Mathieu E, Burls A & Oxman AD 2010, “A pragmatic randomised trial of stretching before and after physical activity to prevent injury and soreness”, British Journal of Sports Medicine, vol. 44, pp. 1002-1009, doi:10.1136/bjsm.2009.062232
“Stretching before and after physical activity does not appreciably reduce all-injury risk but probably reduces the risk of some injuries, and does reduce the risk of bothersome soreness.”

9. McHugh MP & Cosgrave CH 2010, “To stretch or not to stretch: the role of stretching in injury prevention and performance”, Scandinavian Journal of Medicine & Science in Sports, no. 20, pp. 169–181, doi: 10.1111/j.1600-0838.2009.01058.x
“There is an abundance of literature demonstrating that a single bout of stretching acutely impairs muscle strength, with a lesser effect on power… With respect to the effect of pre-participation stretching on injury prevention a limited number of studies of varying quality have shown mixed results. A general consensus is that stretching in addition to warm-up does not affect the incidence of overuse injuries. There is evidence that pre-participation stretching reduces the incidence of muscle strains but there is clearly a need for further work.”

10. Mason DL, Dickens VA & Vail A 2008, “Rehabilitation for hamstring injuries”, Cochrane Database of Systematic Reviews 2007, issue 1, art. no., CD004575, DOI: 10.1002/14651858.CD004575.pub2
“Hamstring injuries are commonly encountered in sports medicine, and clinical management of this problem can differ widely. There is limited evidence to suggest that rate of recovery can be increased with an increased daily frequency of hamstring stretching exercises.”

11. Thacker SB, Gilchrist J, Stroup DF & Kimsey CD Jr 2004, “The impact of stretching on sports injury risk: a systematic review of the literature”, Medicine and Science in Sports and Exercise, vol. 36, no. 3, pp. 371-378, PMID: 15076777
“Six of 361 identified articles compared stretching with other methods to prevent injury. There is not sufficient evidence to endorse or discontinue routine stretching before or after exercise to prevent injury among competitive or recreational athletes.”

12. Herbert RD & Gabriel M 2002, “Effects of stretching before and after exercising on muscle soreness and risk of injury: systematic review”, British Medical Journal 325:468, doi: http://dx.doi.org/10.1136/bmj.325.7362.468
“Stretching before or after exercising does not confer protection from muscle soreness. Stretching before exercising does not seem to confer a practically useful reduction in the risk of injury.”

13. Pope RP, Herbert RD, Kirwan JD & Graham BJ 2000, “A randomized trial of preexercise stretching for prevention of lower-limb injury”, Medicine and Science in Sports and Exercise, vol. 32, no. 2, pp. 271-277, PMID: 10694106
“1538 male army recruits were randomly allocated to stretch or control groups. During the ensuing 12 wk of training, both groups performed active warm-up exercises before physical training sessions. In addition, the stretch group performed one 20-s static stretch under supervision for each of six major leg muscle groups during every warm-up. The control group did not stretch… There were 158 injuries in the stretch group and 175 in the control group… A typical muscle stretching protocol performed during preexercise warm-ups does not produce clinically meaningful reductions in risk of exercise-related injury in army recruits. Fitness may be an important, modifiable risk factor.”

14. Shrier I 1999, “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 Sport Medicine, vol. 9, no. 4, pp. 221-227, PMID: 10593217
“Stretching before exercise does not reduce the risk of local muscle injury: a critical review of the clinical and basic science literature.”

Advertisements

One thought on “Stretching credulity

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s