Stretch and Flexibility Part 3: Should flexibility be retired as a component of fitness?

Flexibility on the hot seat:

Thanks for being "flexible" through part 1 and part 2 of this series as we laid the foundation to be able to answer the question, "Should flexibility be retired as a major component of fitness?" Let's stretch, then jump right into it. Or just jump right into it?!? 

The answer is... maybe. As with everything else, we need to break the question down to give a credible answer. After all, the United States Department of Health and Human Services defines physical fitness as "a set of attributes that people have or achieve that are related to the ability to perform physical activity." When looking at a training stimulus being part of a major component of fitness, we should ask: 

1. Does it decrease injury risk? 
2. Does it lead to robust health benefits such as longevity, body composition, cardiorespiratory fitness, and overall functional abilities?

Does stretching reduce injury? 

Although this is a commonly held belief, research has shown little to no effect on preventing injury. A review by Lauerson et al. concluded that the injury prevention effect of stretching was clinically useless. The review noted, "...consistently favorable estimates were obtained for all injury prevent measures except stretching." Furthermore, a meta analysis in the military that included 15 studies using GRADE assessment compared static stretching to no stretching in 3,532 participants. The findings showed low quality of evidence indicating no favorable effect from stretching. 

Is flexibility a risk factor for injury? 

As defined previously, flexibility is the intrinsic property of a tissue and the subjective toleration to absolute range of motion in a joint or series of joints. Is flexibility important for sport and activities of daily living? YES! If you can't reach down to put your pants on, that's a big issue. Unless, of course, you join the cast of the LEGO movie, "Honey, where are my pants?" or are conducting tele-health appointments. I'd argue flexibility is needed in every sport and becomes even more important in gymnastics, performing arts, CrossFit, Olympic Lifting, softball, and baseball to name a few. 

For example, Wilk et al demonstrated pitchers with >5 degree deficit in flexion and >5 degrees deficit in total rotation lead to a 2.6 and 2.8 increased chance of injury, respectively. 

Flexibility is important but how we get there may be more important! We learned in part 2 of this series that static stretching only causes short lived changes in flexibility, whereas strength training can provide long term benefits. Nuzzo noted "flexibility can be maintained or improved by exercise modalities that cause more robust health benefits than stretching (e.g., resistance training)." Injury reduction programs consisting of strengthening have consistently shown positive results. The study by Lauerson et al. noted previously showed that strength training programs reduced the risk of sports injury by an average of 66-69 percent and may halve the risk of overuse injuries.

Lastly, we have to address why there is even a limitation in flexibility. Our complex systems are very intelligent and will provide protection when needed, but sometimes when it is not needed. If an athlete is fearful or uncertain of a particular movement they will naturally and intelligently guard it, not allowing "flexibility." In other words, is it possible our limitations in flexibility and range of motion changes are a byproduct of pain, fear, or other psychological factors? To improve flexibility in this case we have to remove the threat and show the brain that it is safe to move freely. Once safety is established, boom; flexibility improved, likelihood of future injury reduced (because we are also going to load and get strong in new ranges... or maybe because they have confidence and newfound trust in the injured area... or maybe some other reason?)! 

Does flexibility training cause robust fitness benefits? 

Nuzzo highlights "flexibility has little predictive or concurrent validity with health and performance outcomes (e.g., mortality, falls, occupational performance) in apparently healthy individuals." If flexibility is failing to show its utility as an asset to perform physical activity, then maybe it should be retired and physical fitness testing should emphasize strength, endurance, body composition, and cardiorespiratory fitness. A strong argument is that retiring flexibility will simplify fitness batteries. Nuzzo argues it would, "save time and resources dedicated to flexibility instruction, measurement, and evaluation; and prevent erroneous conclusions about fitness status when interpreting flexibility scores." This would allow us to spend more time and money in areas of fitness that cause robust health benefits. 

Should flexibility be retired altogether? 

Negative, Batman! However, the way we view flexibility and its treatment efficacy, clinical utility, and cost-effectiveness needs to change. Flexibility is needed for performance in various sports and activities of daily life, however it does not need to be achieved through static stretching. Although static stretching is likely NOT harmful, the time it takes away from treatments or stimuli that cause robust fitness benefits is. If the individual has a strong belief that stretching is the best stimulus to improve their flexibility, then it may be best to agree and offer strengthening as an adjunct. 

"The teacher only appears when the student is ready." ~origins from Mabel Collins 

Any opportunity to give a person back control of their health is an opportunity well worth it. But at the same time...

"The greater the doubt, the greater the awakening; the smaller the doubt, the smaller the awakening, No doubt, no awakening." ~C.C. Chang

Regardless of belief in static stretching, it is important to remain open-minded and willing to change perspective given new evidence. Maybe that individual will have a bigger awakening and become a bigger aerobic/resistance training fan!

Lastly, it should be noted that studies looking at static stretching do not look at the beneficial components of pregame rituals, team communication, and mindset. These components are just as important to performance as strength training, however we believe they can be achieved in the absence of static stretching as they are not limited to that specific modality.

We conclude that the All Blacks Haka pregame routine is the best ritual/warm-up ever made and that flexibility should not be abandoned, but rather viewed and achieved through stimuli that cause more robust health benefits. 

References: 

1. Mine and Dr. Jason Tuori's, PT, DPT, CSCS thoughts

2. Lauersen JB, Bertelsen DM, Andersen LB

The effectiveness of exercise interventions to prevent sports injuries: a systematic review and meta-analysis of randomised controlled trials 

British Journal of Sports Medicine 2014;48:871-877.

3.Dijksma I, Arslan IG, Van etten-jamaludin FS, Elbers RG, Lucas C, Stuiver MM. Exercise Programs to Reduce the Risk of Musculoskeletal Injuries in Military Personnel: A Systematic Review and Meta-Analysis. PM R. 2020.

4. Available at: https://bestpractice.bmj.com/info/us/toolkit/learn-ebm/what-is-grade/

5. Wilk KE, Macrina LC, Fleisig GS, et al. Deficits in glenohumeral passive range of motion increase risk of elbow injury in professional baseball pitchers: a prospective study. Am J Sports Med. 2014;42(9):2075-81.

6. Nuzzo JL. The Case for Retiring Flexibility as a Major Component of Physical Fitness. Sports Med. 2020;50(5):853-870.

7. Hart L. Effect of stretching on sport injury risk: a review. Clin J Sport Med. 2005;15(2):113.

8. Chaabene H, Behm DG, Negra Y, Granacher U. Acute Effects of Static Stretching on Muscle Strength and Power: An Attempt to Clarify Previous Caveats. Front Physiol. 2019;10:1468.