Introduction

You have probably heard many opinions on stretching. The type, timing, and goals of stretching are debated by healthcare professionals, often leaving the average person in the dark. What kind of stretching should you do? When are you supposed to do it? Do you actually even need to stretch at all?

People stretch to improve flexibility, improve performance, or prevent injuries, but the claims about stretching can range from humble to exaggerated. How would you know that stretching is worth your time, without performing your own little experiment?

Unfortunately, like most topics in healthcare, these simple questions are hard to answer. The research on stretching goes back decades, and many of the questions above have been thoroughly investigated. Stretching is a staple treatment of physical therapists, massage therapists, chiropractors, and personal trainers. It typically has a place in physical therapy treatments, exercise programs, or sports programs.

Opinions have changed throughout the years, but there is enough evidence to make some firm conclusions. This article will go through the science in regards to dynamic stretching in comparison to traditional static stretching and will help you decide if dynamic stretching is something you should be doing.

What Are The Types Of Stretching?

There are many different types of stretching, each with their own set of guidelines.

  • Dynamic stretching: Dynamic stretching involves the movement of joints through their full range of motion in a slow and controlled manner. There are no extended holds, and they are typically used as a warm-up activity before exercise or a sporting event. Often, the type of movement prescribed is similar to the activity that is about to be performed. Specific recommendations for what movements to perform, how many repetitions to perform, and how long it should all take can vary, but most resources recommend 5-10 minutes of sport-specific movements. Examples of dynamic stretching include exercises like the “high knees” or “butt kicks” that are typically performed before running.
  • Static stretching: Static stretching is what everyone thinks of when you picture someone stretching; getting into a funky position and holding it for awhile. This type of stretching typically involves moving the back, arms, or legs into specific positions and holding for an extended period of time. Holds for 15-30 seconds at a time for 3-5 times are commonly prescribed, but timing can vary based on who you ask. Static stretching can be performed actively by using your own muscles to hold the positions, or passively by using some external force like a strap, a wall, or another person. Examples of static stretching include bending down and touching your toes, or standing on the edge of a step and letting your heels drop down.
  • PNF stretching: Proprioceptive neuromuscular facilitation stretching is a fancy name for a simple type of stretching that involves squeezing the muscle being stretched and/or squeezing the muscle on the opposite side. The theory is that the squeezing helps the muscles relax and elongate more. There are many different techniques with even fancier sounding names, but they are all essentially the same process of performing a static stretch, tightening one or more muscles, relaxing, and going further into the stretch.
  • Ballistic stretching: Ballistic stretching utilizes bouncing movements to stretch into different positions, but has fallen out of favor. This is similar to dynamic stretching, but is used with more momentum and performed with less control. In the literature, ballistic stretching is often considered a subtype of dynamic stretching, but for the purpose of this article we will leave ballistic stretching out.

Each type of stretching may have their own applications, but are typically used to improve flexibility, reduce a person’s risk of injury, or improve performance. Each one of these is a separate question and requires an in-depth look at the science.

Is Dynamic Stretching Better Than Static Stretching…

…For Improving Flexibility?

Is Dynamic Stretching Even Effective?

The most obvious use of stretching is for improving flexibility, and there is plenty of evidence supporting that it does. Dynamic stretching can improve range of motion (ROM) and flexibility, as typically measured with the classic sit and reach test or various range of motion tests of different joints (1, 2, 3, 4, 9, 11, 15, 17, 19, 21, 24).

Citing multiple studies, one researcher wrote in his analysis that “there is considerable evidence that an acute bout of dynamic stretching can enhance ROM around a joint” (19).

Do We Know Which Is Better?

However, the question of which mode of stretching is better for improving flexibility is a bit more complicated. The research is much more mixed, with some studies suggesting that dynamic is better (1, 2), some saying static is better (16, 18, 20), or some saying they both have similar effects (5, 9, 11, 17, 21).

We don’t know exactly how stretching works, but there may be multiple factors involved. Some include the elastic properties of human tissue (i.e. how stretchy it is), tissue temperature, neurological considerations (the influence of the nervous system), and general stretch tolerance.

Dynamic stretching may help by increasing the temperature of the muscles as well as improving general stretch tolerance, whereas slower static stretching may help improve the elasticity of the muscles over time.

Bottom Line

If your goal is to improve your flexibility and nothing else, dynamic stretching or static stretching are both reasonable ways to do it. Since there is not one clear winner in the research, try both and do whatever feels better for you.

However, if your particular sport or activity requires significant flexibility or the ability to maintain certain positions, such as in gymnastics or dance, static stretching may have the edge due to the need for increased tissue elasticity.

…For Reducing Risk Of Injury?

Another proposed benefit of stretching before or after exercise, or as part of a regular routine, is the prevention of injuries. This is a practically universal recommendation from coaches, trainers, and healthcare professionals. But does regular stretching actually make you less likely to get injured? And more specifically, is there any difference between dynamic and static stretching in regards to injury risk?

Does General Stretching Help?

As researcher Erik Witvrouw puts it, stretching and injury prevention have “an obscure relationship” (26). Although it seems plausible that general stretching would be able to reduce a person’s risk of injury, the research has illuminated a less than clear link between the two.

Many systematic reviews, meta-analyses, and informal literature reviews of many studies have not found strong evidence showing that people who stretch are less likely to be injured (3, 13, 14, 23, 25). However, two reviews, (14, 25), found there is some preliminary evidence that stretching may reduce muscle strain injuries.

Is There Any Evidence For Dynamic Stretching?

There aren’t many studies looking at dynamic stretching specifically for its role in injury prevention. One review (3) noted that of the 12 studies they found for their review, none of them included dynamic stretching. In another study from 2018 investigating stretching, the authors write, “no detailed studies have examined the effects of dynamic stretching on injury risk” (6).

One study (27) looked at injury rates for soccer teams; both groups performed a dynamic stretching warm-up, but one group also performed some static stretching. They found that there were no differences between groups, suggesting that static stretching did not add anything to the equation.

Unfortunately, they did not use a control group that did not use dynamic stretching at all, so we cannot draw any conclusions on dynamic stretching itself.  

Bottom Line

The science suggests that general stretching probably does not reduce your risk of injury during exercise or sports in any appreciable way, but it may have a small effect on reducing the rate of muscle strains. There is not enough research specifically on dynamic stretching to know if it can help either.

Right now, we have no reason to believe that stretching of any kind prevents injuries, but this may change if stronger research comes out.

…For Improving Performance?

Does Static Stretching Improve Performance?

The inclusion of dynamic stretching in warm-up routines before physical activity, exercise, or sporting events has recently increased in popularity. It is well established that static stretching can worsen certain aspects of performance, including, speed, strength, and power (12, 22). However, one of those studies (12) showed that the negative effects of static stretching are only seen with stretches greater than 60 seconds.

For stretching lasting less than 45 seconds, performance decreases are not seen. Nonetheless, static stretching prior to activity has fallen out of favor. Many sought new exercises or techniques to fill the gap. An explosion of research looking at the effects of dynamic stretching on performance came out.

How About Dynamic Stretching?

Unfortunately, the relationship between dynamic stretching and performance is less than clear but a few broad trends have emerged from robust reviews and trials. Research has shown that dynamic stretching is generally not associated with performance decreases, and may improve performance by a little bit.  

A systematic review of dynamic stretching from 2015 reported “an examination of the data revealed that the weighted mean performance enhancement associated with DS was 1.3%…thus, although there are occasions in which moderate or large improvements in performance are reported, overall, no robust evidence exists for substantial performance enhancements after DS” (3).

However, a later review of 84 studies showed that despite many studies that showed neutral or negative effects of dynamic stretching on performance, the majority showed small improvements. “There is a strong body of evidence supporting the positive or neutral effects of dynamic stretching on subsequent muscular performance” (19).

A quick literature search will reveal that one can find trials of varying quality that show all of the possible outcomes: dynamic stretching can improve performance, have no effect, or worsen it. (1, 6, 7, 8, 9, 10, 13, 16, 17, 20, 28).

Bottom Line

The literature on dynamic stretching and performance is deep, varied, and confusing for the average person as well as any healthcare professional. The broad trend is dynamic stretching may improve performance by a small amount that is of debatable importance, or it has no effect.

Static stretching has been clearly shown to worsen performance by small amounts. If you are an athlete, dynamic stretching should be performed instead of static stretching as a warm-up activity. If you are just an average gym-goer or a recreational athlete, the effects of dynamic stretching are probably too small to notice or don’t exist at all.

Is Dynamic Stretching Safe?

There were no studies that I came across that specifically assessed the safety of dynamic stretching. For most people, in the absence of any existing injuries or conditions, dynamic stretching can be a safe activity, as long as the person stretching is monitoring what he or she is doing, and is moving in a careful and controlled manner.

For those with injuries or pain, one should consult a physician, physical therapist, or another qualified healthcare professional for advice if there are any questions or concerns. Speaking anecdotally as a physical therapist, most people can be instructed on how to stretch properly without any issue, and the easiest way to ensure that dynamic stretching is a safe activity is to start slow, move to the point of slight discomfort, and avoid movements or stretches that cause pain.

Conclusions

Like many topics in health care, simple questions don’t have simple answers. The literature in regards to stretching, and more specifically dynamic stretching versus static stretching, is dense, complicated and difficult to comb through. Some broad trends do emerge, however.

Both dynamic and static stretching can be effective ways to improve flexibility and maintain range of motion. There is no strong evidence to suggest static stretching can prevent injuries, and there is not enough research on dynamic stretching to draw any conclusions. Fairly robust evidence shows that static stretching can decrease performance by small amounts, and dynamic stretching may improve performance by small amounts or have no effect.

From the evidence, it is reasonable to conclude that dynamic stretching can be useful for flexibility training, as well as a warm-up  before an activity or sport. The importance of stretching may be overhyped, but the evidence shows clear, albeit small beneficial effects.

It is reasonable to include dynamic stretching movements in your exercise routine for general health, but do not expect them to have a huge effect on your risk of injury or performance.

Recommendations

  • Dynamic stretching is probably equally effective as static stretching for increasing flexibility.
  • There is not enough research to know if dynamic stretching prevents injury, but static stretching is not likely to do it either.
  • Pre-activity dynamic stretching may improve performance by small amounts or not at all.
  • Dynamic stretching is a safe activity that anyone can include in their exercise program if they choose.