Has Science Really Proven Stretching is More Harmful Than  Beneficial?

Has Science Really Proven Stretching is More Harmful Than  Beneficial?

Sports medicine has advanced significantly over the last decade.  Specialists in the field today have access to resources and tools that  where not readily available twenty years ago. This has enabled exercise  professionals to conduct clinical studies to help distinguish  pseudoscience from facts.  

A popular concept that has been under the microscope recently is the  impact that stretching has on athletes if done before exercise. Some  coaches and trainers swear by this and include it in their warm sessions  while others skip it. Cell Sauce decided to research this question and  this is what we’ve learned.


Types of Stretching 

Here are a few of the stretching techniques widely used in sports and  exercise.  

Static stretching is stretching in which a position stretching a muscle is  assumed, and then held in position for specific time [2]. This is the most  common type of stretching; it is also considered the safest [1].  

Dynamic Stretching is movement based stretching. This is typically  used as a warm up before activity. The movements are done similar to  what you would do in your sport. The movements are taken to the end  of your ROM but don’t exceed ROM like Ballistic stretching. An example  of dynamic stretching would be slow, controlled leg swings, arm  swings, or torso twists.  

Ballistic stretching is stretching using the momentum of a ballistic  movement to enhance the effects [2]. An example is when an athlete  stands on a step and bounces on their toes so that the heal goes below  stepping height and then above it. Ballistic stretching can cause injury if  not done correctly, it is only recommended for skilled athletes.  

Proprioceptive neuromuscular facilitation (PNF) is a stretching  technique in which the muscle to be stretched is first contracted  maximally, then the muscle is then relaxed, and is either actively 

stretched by contraction of the opposing muscle or is passively  stretched [1]. Simply explained, this is when you extend a joints range  of motion (ROM) through assistance. Typically this type of stretching is  done with a partner or tools.  

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What happens to muscles when you stretch? 

Increased ROM is the primary reason why stretching is important in  sports and exercise. In this regard, broader understanding into  stretching is useful. For the next few seconds, imagine zooming out  from a muscle fiber in slow motion.  

Stretching begins deep in the muscle fiber with the sarcomere, the  basic unit of contraction in the muscle fiber. As the sarcomere  contracts, the area of overlap between the thick and thin myofilaments  increases [3]. As it stretches, this area of overlap decreases, allowing  the muscle fiber to elongate [3].  

Once the muscle fiber is at its maximum resting length, when all the  sarcomeres are fully stretched, additional stretching places force on the  surrounding connective tissue [3].  

As the tension increases, the collagen fibers in the connective tissue  align themselves along the same line of force as the tension. Hence,  when you stretch, the muscle fiber is pulled out to its full length,  sarcomere by sarcomere, and then the connective tissue takes up the  remaining slack [3]. When this occurs, it helps to realign any  disorganized fibers in the direction of the tension.  

Once the muscle is fully stretched, you may start to notice twitching or  spasm. This is known as myoclonus, it means the muscle group has  stretched to its maximum ability [1].  

When this process happens repeatedly, musculotendinous tissues  adapt to a new position! It is through this process that flexibility and  ROM is improved. This has several benefits including good health,  good posture, reduced risk of injury and improved performance. 

So Stretching is Good For Your Body, But Should You Stretch Before  Exercise? 

It has been a common practice over the past few decades to stretch  before exercise. But does it actually prevent injury, improve  performance, or prevent delayed onset muscle soreness (DOMS). If you  are suffering from post workout soreness you can use our recovery  products to help speed up recovery and reduce soreness.  

The rationale for stretching before exercise activity is that stretching  increases the compliance, by decreasing the stiffness of the tendon unit  and thus, theoretically, makes it less prone to injury before exercise  activity [1]. Sounds logical, right.  

Unfortunately, these recommendations, are not based on research [1]. 

According to this study The basic science literature supports the  epidemiologic evidence that stretching before exercise does not reduce  the risk of injury.  

Here’s what they found - first, stretching before exercise should have no  effect for activities in which excessive muscle length is not an issue  (e.g., jogging). Second, stretching won't affect muscle compliance  during eccentric activity, when most strains are believed to occur. Third, 

stretching can produce damage at the cytoskeleton level. Fourth,  stretching appears to mask muscle pain in humans.  

Many studies have found that stretching prior to or after exercise does  little to prevent either injury or muscle soreness [1] [4] [5]. This means  stretching before exercise might just be a waste of time. Some clinical  studies even found that stretching immediately before exercise may  

cause performance decrements [1].  

What Should You Do?  

The best advice based is to using dynamic stretching and sport  specific movements before your exercise to warm up.  

And then on non training days focus on stretching to improve flexibility  and range of motion.  


[1] D. L. S. Sharon A. Plowman, Exercise Physiology For health,  fitness, and performance, Baltimore: Lippincott Williams & Wilkins,  2011.  

[2] K. M. H. S. Heather Bateman, Dictionary of Sport and Exercise  Science, London: A & C Black Publishers Ltd, 2006.  

[3] B. Appleton, "Stretching and flexibility, everything you never  wanted to know," Massachusetts Institute of Technology, 6 January  1996. [Online]. Available: https://web.mit.edu/tkd/stretch/ stretching_2.html. [Accessed 15 April 2022].  

[4] Shrier Ian, "Stretching Before Exercise Does Not Reduce the Risk  of Local Muscle Injury: A Critical Review of the Clinical and Basic  Science," Clinical Journal of Sport Medicine, vol. 9, no. 4, pp. 221 - 227,  1999.  

[5] S. S. M. T. A. Konrad, "Effects of acute static, ballistic, and PNF  stretching exercise on the muscle and tendon tissue properties," 

Scandinavian Journal of Medicine & Science In Sports, vol. I, no. 27, p.  1070–1080, 2017.