The Science Behind Stretching

Prevention & Recovery -

The Science Behind Stretching

 

Should I be Stretching?
This may sound like a rhetorical question as it is widely understood that flexibility is an important component of overall fitness. Nonetheless, the role of stretching as it relates to physical activity remains a topic of much debate. Consensus among wellness professionals regarding its utility was achieved long ago, though opinions often vary in terms of its application. Read below to determine the best way to implement stretching in your routine.

What Does Stretching Do?
More accurately, the question should be phrased “What should stretching do?”, as the desired effects are dependent on a few factors we will discuss a bit later. Ideally, a good stretching protocol should minimize the risk of injury and enhance performance through improved flexibility. This phenomenon occurs at the cellular level and is related to muscles’ elasticity, or ability to return to original length. This concept sure seems logical enough, so why is there disagreement among professionals pertaining to the benefit of stretching? Why shouldn’t I make it a personal goal to gain as much flexibility as possible? Why not walk into the gym and spend 5, 10, or even 20 minutes stretching before I exercise? These are just a few of the questions that have kept researchers up at night for decades.

How (and When) Do I Stretch?
Now we are getting to the root of the debate. Even if you are unfamiliar with the current literature, simply engaging in a little people-watching at your local gym should make it obvious that there seems to be a broad array of stretching practices. Imagining the stretching routine often found on football fields in the 1960s would likely conjure up similar confusion when compared to the pre-performance routines of their modern counterparts. So who is right?

The variability in implementation is likely a function of the variability of information. So keeping in mind the previously discussed goals of stretching, what has science taught us?

Like many times throughout history (UV light, ice cream, etc.) we initially did not understand the concept of “too much of a good thing”. This accounts for the seemingly endless static stretching programs (holding a stretch for a prolonged period) often seen in historical footage of various sporting events.

A few decades ago, research revealed that static stretching may actually hinder athletic performance. This adverse effect has been repeatedly demonstrated in activities related to strength, power, and speed.

More recently, there has been a number of systematic reviews aimed at examining much of the available literature regarding the relationship between stretching and athletic performance. There seems to be agreement that dynamic stretching (progressively moving a joint or muscle through an active range of motion) is superior to static stretching prior to activity. Additionally, the negative effects of static stretching seem to be dose dependent, i.e. more likely when stretches are sustained for greater than 60 seconds. Lastly, stretching seems to be associated with increased flexibility, though it does not appear to reduce the risk of injury.

So What Does This All Mean?
It means that static stretching prior to activity neither enhances performance, nor reduces the risk of injury. This is likely a multifactorial process though chiefly related to stretching a muscle beyond the optimal length for contraction, as well as initiating a feedback loop in which a cold muscle is stretched – the brain senses pain – and in turn, calls for muscle guarding (involuntary tensing as a defense mechanism) to prevent the perceived injury.

OK, So Don’t Stretch?
Not exactly. Despite the various undesirable effects of static stretching, there is still a time and a place for this activity. The American College of Sports Medicine (ACSM) recommends 2-3 days of stretching per week, holding stretches 10-30 seconds, and repeating 2-4 times per stretch to achieve a total of 60 seconds for each stretch. They also believe static, dynamic, ballistic (using momentum to force a muscle beyond its normal range of motion, i.e. bouncing), and proprioceptive neuromuscular facilitation (actively contracting a muscle, followed by relaxation and stretching) to be effective in this setting. Note that these recommendations are not associated with a particular time – so feel free to stretch whenever you want… just not before activity!

Achieving the benefits of static stretching are more likely if performed after activity. This avoids the aforementioned feedback loop by stretching the muscle when it is warm and more pliable.

So What Do I Do Before Activity?
Great question – learning what not to do is only part of the equation. The best practice is likely a dynamic warm-up. As the name suggests, this is simply elevating the temperature (and pliability) of the muscle through increased heart rate and blood flow. This can be done effectively any number of ways from doing jumping-jacks, to performing more specific movements such as variations in lunges, skipping, or reduced-effort running.

The Take Home Message
Flexibility is a key component of physical fitness, though traditional static stretching is actually counterproductive to performance goals if done prior to activity. A better practice involves a pre-performance dynamic warm-up that can be generalized or activity-specific. Static stretching (as well as other methods) can be performed safely and effectively after a muscle is warm (i.e after activity) to reap the most benefits and avoid unwanted effects.

Author: Dr. Anthony Dugarte, M.D. C.S.C.S.
Dr. Anthony Dugarte has enjoyed success in academics, as well as collegiate sports. He accepted a full athletic scholarship to attend Kent State University and graduated, Cum Laude, with a B.S. in Exercise Physiology. While at Kent, Dr. Dugarte was a member of the Golden Flash Football Team and earned Academic All-American Honors as a defensive lineman.

Prior to continuing his education, Dr. Dugarte worked as an Exercise Physiologist in an outpatient physical therapy. During this time, he became a Certified Strength and Conditioning Specialist and now boasts over 10 years’ experience in the field.

A 2016 graduate, Dr. Dugarte obtained his medical training at Case Western Reserve University School of Medicine. Most recently, Dr. Dugarte completed a postgraduate Research Fellowship in Orthopaedic Trauma at Regions Hospital in St. Paul, Minnesota. While a fellow, he garnered invaluable experience in virtually every aspect of the research process. While he plans to continue his training in an Orthopaedic Surgery residency, Dr. Dugarte is passionate about sharing the knowledge he has acquired through creative and technical writing.

References:

  1. Ayala, Francisco & De Ste Croix, Mark & Sainz de Baranda, Pilar & Santonja, Fernando. Acute effects of two different stretching techniques on isokinetic strength and power. Revista Andaluza de Medicina del Deporte. 2015. 8. 93-102. 10.1016/j.ramd.2014.06.003.
  2. Mccrary, J. & Ackermann, Bronwen & Halaki, Mark. (2015). A systematic review of the effects of upper body warm-up on performance and injury. British journal of sports medicine. 49. 10.1136/bjsports-2014-094228.
  3. Curry, Brad & Chengkalath, Devendra & Crouch, Gordon & Romance, Michelle & Manns, Patricia. (2009). Acute Effects of Dynamic Stretching, Static Stretching, and Light Aerobic Activity on Muscular Performance in Women. Journal of strength and conditioning research / National Strength & Conditioning Association. 23. 1811-9. 10.1519/JSC.0b013e3181b73c2b.
  4. Kay, Anthony & Blazevich, Anthony. (2012). Effect of Acute Static Stretch on Maximal Muscle Performance: A Systematic Review. Medicine and science in sports and exercise. 44. 154-64. 10.1249/MSS.0b013e318225cb27.
  5. Behm, David & Kibele, Armin. (2007). Effects of differing intensities of static stretching on jump performance. European journal of applied physiology. 101. 587-94. 10.1007/s00421-007-0533-5.
  6. Thacker, Stephen & Gilchrist, Julie & Stroup, Donna & Kimsey, C. (2004). The Impact of Stretching on Sports Injury Risk: A Systematic Review of the Literature. Medicine and science in sports and exercise. 36. 371-8. 10.1249/01.MSS.0000117134.83018.F7.

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