Stretching is thought to be one of the most important pillars of physical fitness.

It’s essentially a religion to people in and out of the fitness space.

But what does the “science” actually tell us about stretching?

That stretching is not only overhyped, but may be a waste of your time.

Let’s dive in.

Definitions

Paul is a science communicator and writer based out of Canada, and the newsletter I’ve written below is largely based on a 35,000-word article he wrote on stretching. You can think of this newsletter as a more concise version of his work, with a couple of original Modern Meatheads insights from me. Strong shout out to Paul!

There are two major types of stretching:

• Static stretching - holding a single position for a while, progressively moving “deeper” into that position over time. Static stretches are generally held for longer periods until the desired range of motion expands.

• Dynamic stretching - stretching using motion. You can think of dynamic stretching as non-specific exercises that are meant to improve range of motion transiently.

  • To the extent that dynamic stretching “works”, it’s probably because it’s just a less-loaded version of normal exercise.

People typically include a stretching routine for one of the following reasons (all of which we will debunk today):

1. To “warm-up”.

2. To become more flexible.

3. Prevention of soreness.

4. Prevention of injury.

5. To enhance performance.

Stretching to “Warm-Up”

Warm-ups are an important part of the exercise process.

The purpose of a warm-up is to prepare for a given activity.

That’s it.

Specific warm-ups - those that essentially mimic the future task at reduced effort - have been shown to minimize the risk of getting injured.

But non-specific warm-ups, like stretching, have not.

In fact, of the currently available evidence we have, static stretching before sport-specific activity has been shown to create no effect or a net-negative effect on injury and performance.

Stretching to Reduce Soreness & Improve Recovery

Muscle soreness - commonly referred to as “DOMS” - is not clearly understood in the literature, especially as it relates to solutions to prevent or reduce it.

One research review commented that the “mechanisms, treatment strategies, and impact on athletic performance remain uncertain, despite the high incidence of DOMS”.

Muscle soreness is a natural consequence of exercise, and could represent the body’s response to any number of things, including inflammation, muscle or connective damage, and more.

Many believe that stretching reduces DOMS, despite clear evidence to the contrary - and two notable research reviews have concluded this explicitly.

Exercise itself has been shown as one of the only effective means of alleviating pain during DOMS, despite this effect being temporary.

In other words, our best strategy to reduce DOMS is simply time and appropriate recovery.

Stretching to Prevent or Recover From Injury

In a review that analyzed 5 controlled studies, the authors concluded that “limited evidence showed stretching had no effect in reducing injuries”.

Another review, which included 6 articles, concluded that “there is not sufficient evidence to endorse or discontinue routine stretching before or after exercise to prevent injury among competitive or recreational athletes” (i.e., an inconclusive takeaway).

In a randomized controlled trial of over 1,000 army recruits, the authors concluded that “there were no significant differences in incidence of injury between the prevention group and the placebo group”. The prevention group, in this case, performed an injury prevention routine, which included stretching in an attempt to improve flexibility.

Another review - which included 25 trials, over 26,000 participants, and over 3,400 injuries - concluded that “consistently favorable estimates were obtained for all injury prevention measures except for stretching”.

In (yet) another large randomized study of the impact of pre-run stretching on the risk of injury, the authors concluded that “there was no statistically significant difference in injury rates between the stretch and no stretch groups for any specific injury location or diagnosis”.

Keep in mind that these are not trivial results and that most of these reviews include several hundred to thousands of participants across a multitude of injury scenarios.

The evidence here is abundant and clear - stretching does not prevent or reduce injury.

One caveat worth mentioning: the jury is out on what may be the most effective means of recovering from injury.

Most evidence-based therapists seem to conclude something similar, however - that rehab is just a scaled-down version of exercise, and that effective rehab = effective exercise selection, execution, and load management.

Many methods work, and every rehabilitation program should be specific to individual contexts.

My personal bias leads me to believe that stretching in rehabilitation settings should be done with extreme caution, if at all.

Improving contraction as a primary focus is likely to yield as effective (or better) results compared to stretching, especially longer-term - we simply don’t have the data to suggest that stretching is superior to any other methodology of rehab at this point.

Stretching to Improve Performance

Pre-exercise or pre-sport-stretching may actually reduce performance.

A systematic review - mentioned earlier - with over 100 articles showed that bouts of static stretching over 60 seconds showed detrimental effects on strength.

Another study showed that static stretching “impaired neuromuscular function, resulting in a slow start during a 3-km running time-trial”.

While this is most likely a small and highly time-dependent effect, there’s no upside to longer bouts of stretching before activity, as we’ve already debunked.

Here are several other articles that showed similar effects:

• One study compared dynamic to static stretching before a series of sprints done over 20 meters. The static stretching group experienced a decrease in performance (65% of results) by the third sprint compared to the dynamic stretching group.

• Another study showed reduced biking performance in groups that static stretched compared to those that didn’t.

• Another study showed that strength in the hamstrings dropped ~12% after static stretching. Regular hamstring stretching showed mixed results, with improved strength at longer lengths, but reduced strength at shorter lengths (a potential win for stretchers!?).

• Another study showed an 8% reduction in performance in stretching groups in a 1-mile uphill run.

What does stretching actually do?

Stretching - without a doubt - improves our flexibility.

Whether or not flexibility should be a desired adaptation, however, is not clear.

The mechanisms that cause this aren’t completely clear, but improved flexibility seems to be related to changes in neurological “tone” more so than differences in tissue itself.

In other words - a change in flexibility appears to be a matter of tolerance change, not structural change.

If our goals are to seek improvements in range of motion - for whatever reason - strength training has been found equally as effective as stretching.

However, motivation to improve range of motion in the first place may be a means to no end. This is a topic that is yet to be hashed out in the literature.

In other words, flexibility and mobility have no direct relationship with improved health outcomes of any kind.

This may shock some of you, but it’s true!

Now, I don’t mean to say that range of motion of a joint is unimportant - range of motion is an indirect proxy for appropriately functioning tissues.

But that’s about all we can say about range of motion, at the moment.

Is stretching good for anything?

While there don’t appear to be objective upsides to stretching, I have a hard time believing that appropriately-dosed static stretching is harmful, at least, in healthy individuals performing stretches within tolerance of loading and range.

So, if you like to stretch because it feels good - and you’re being mindful of your comfortable joint ranges - more power to you!

Just make sure that you’re not stretching because of any of the above (currently debunked) beliefs.

I am open-minded and am happy to change my beliefs upon seeing evidence that conflicts with any of the above citations (you can see a list of them below). Please send any relevant literature - if you have it - to me in response to this email.

If you’re ready to learn more from me, check these out:

• My online courses - where you can find my highest-value content that dives into learning anatomy and physics and how you can apply it to lifting immediately.

• My online community - where you can join 70+ other personal trainers collaborating every day. We do 2 live calls every single week and have a private group where we chat 24/7.

• My eBooks - the most accessible, shorter-form way to start learning all this stuff.

• My training programs - don’t care much about the nitty-gritty details of anatomy but want an educated way to apply these principles to training today? These are the training programs for you.

Resources:

1. Kay AD, Blazevich AJ. Effect of acute static stretch on maximal muscle performance: a systematic review. Med Sci Sports Exerc. 2012 Jan;44(1):154-64. doi: 10.1249/MSS.0b013e318225cb27. PMID: 21659901.

2. Soligard T, Myklebust G, Steffen K, Holme I, Silvers H, Bizzini M, Junge A, Dvorak J, Bahr R, Andersen TE. Comprehensive warm-up programme to prevent injuries in young female footballers: cluster randomised controlled trial. BMJ. 2008 Dec 9;337:a2469. doi: 10.1136/bmj.a2469. PMID: 19066253; PMCID: PMC2600961.

3. Soligard T, Nilstad A, Steffen K, et alCompliance with a comprehensive warm-up programme to prevent injuries in youth footballBritish Journal of Sports Medicine 2010;44:787-793.

4. Lund H, Vestergaard-Poulsen P, Kanstrup IL, Sejrsen P. 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. doi: 10.1111/j.1600-0838.1998.tb00195.x. PMID: 9764443.

5. Cheung K, Hume P, Maxwell L. Delayed onset muscle soreness : treatment strategies and performance factors. Sports Med. 2003;33(2):145-64. doi: 10.2165/00007256-200333020-00005. PMID: 12617692.

6. Herbert RD, de Noronha M, Kamper SJ. Stretching to prevent or reduce muscle soreness after exercise. Cochrane Database Syst Rev. 2011 Jul 6;(7):CD004577. doi: 10.1002/14651858.CD004577.pub3. PMID: 21735398.

7. Hart L. Effect of stretching on sport injury risk: a review. Clin J Sport Med. 2005 Mar;15(2):113. doi: 10.1097/01.jsm.0000151869.98555.67. PMID: 15782063.

8. Thacker SB, Gilchrist J, Stroup DF, Kimsey CD Jr. The impact of stretching on sports injury risk: a systematic review of the literature. Med Sci Sports Exerc. 2004 Mar;36(3):371-8. doi: 10.1249/01.mss.0000117134.83018.f7. PMID: 15076777.

9. Brushøj C, Larsen K, Albrecht-Beste E, Nielsen MB, Løye F, Hölmich P. Prevention of overuse injuries by a concurrent exercise program in subjects exposed to an increase in training load: a randomized controlled trial of 1020 army recruits. Am J Sports Med. 2008 Apr;36(4):663-70. doi: 10.1177/0363546508315469. Epub 2008 Mar 12. PMID: 18337359.

10. Pereles D, Roth A, Thompson DJS. A Large, Randomized, Prospective Study of the Impact of a Pre-Run Stretch on the Risk of Injury in Teenage and Older Runners. USATF.org. 2011 Jun 15.

11. Lauersen JB, Bertelsen DM, Andersen LB. The effectiveness of exercise interventions to prevent sports injuries: a systematic review and meta-analysis of randomised controlled trialsBritish Journal of Sports Medicine 2014;48:871-877.

12. Musham C, Hayes PREffect of pre-exercise stretching on repeat sprint performanceBritish Journal of Sports Medicine 2010;44:i27.

13. Wolfe AE, Brown LE, Coburn JW, Kersey RD, Bottaro M. Time course of the effects of static stretching on cycling economy. J Strength Cond Res. 2011 Nov;25(11):2980-4. doi: 10.1519/JSC.0b013e318234e55f. PMID: 21904241.

14. McHugh MP, Tallent J, Johnson CD. The role of neural tension in stretch-induced strength loss. J Strength Cond Res. 2013 May;27(5):1327-32. doi: 10.1519/JSC.0b013e31828a1e73. PMID: 23439335.

15. Lowery RP, Joy JM, Brown LE, Oliveira de Souza E, Wistocki DR, Davis GS, Naimo MA, Zito GA, Wilson JM. Effects of static stretching on 1-mile uphill run performance. J Strength Cond Res. 2014 Jan;28(1):161-7. doi: 10.1519/JSC.0b013e3182956461. PMID: 23588487.

16. Alizadeh S, Daneshjoo A, Zahiri A, Anvar SH, Goudini R, Hicks JP, Konrad A, Behm DG. Resistance Training Induces Improvements in Range of Motion: A Systematic Review and Meta-Analysis. Sports Med. 2023 Mar;53(3):707-722. doi: 10.1007/s40279-022-01804-x. Epub 2023 Jan 9. PMID: 36622555; PMCID: PMC9935664.