Stretching. This little ten-letter word has the capability to cause chaos. Mention something about stretching and prepare to get behind Zeus’s shield because you're in for a full fledged battle.

“F$#@ stretching.”

“Static stretch before training and you’ll be as weak as a noodle.”

“Only hold for 20 seconds at most.”

“Hold for two minutes minimum.”

“Only do dynamic stretching.”

“PNF is where it’s at.”

“Stretching prevents injuries and enhances performance.”

On and on it goes. It seems that everybody has a side, and the amount of information out there is huge. It’s easy to see how someone can get lost in the whole stretching debate. Let’s take an objective look at what we really know about stretching and try to bring a little clarity to the picture. Let’s dig a little deeper without any bias and see if we can unfold this topic a bit.

Types of stretching

Here are some of the basic, most popular varieties of stretching:

  • Static: This is when you take a muscle(s) to an outer range of motion and hold for an extended period of time, usually between 15 and 60 seconds. Many studies in literature use static stretching.
  • Proprioceptive neuromuscular facilitation (PNF): Commonly known as contract relax or hold relax methods, PNF is designed to take advantage of the body's natural protective mechanisms such as reciprocal and autogenic inhibition. For example, let’s take a hamstring stretch. Lie on your back and have your partner hold your leg for a typical hamstring stretch of 10–15 seconds. Next, contract your hamstring while your partner resists for 5–10 seconds and then relax. Through autogenic inhibition, you should be able to go further into the next static stretch. You could also perform the initial 10- to 15-second hamstring stretch and then bend your knee and contract your quads as your partner resists. Again, return to the static stretch and, through reciprocal inhibition, you should be able to go further.
  • Dynamic: A dynamic stretch is when you take a muscle(s) through progressively larger ranges of motion at progressively higher velocities (i.e. leg swings). It's synonymous with dynamic warm ups where you go through active ranges of motion such as lunges, inch worms, high knee runs, and other movements, gradually increasing the range of motion and speed but not holding positions statically.
  • Myofascial release: Muscles are surrounded by a variety of connective tissues, a major one being fascia. Fascia is a tough sheath of tissue that surrounds whole muscles and individual muscle fibers and provides support and protection. Myofascial release is an attempt to loosen and stretch these tissues to allow for greater range of motion and freedom to the muscles they surround.

What and why

Viscoelasticity refers to the property of the muscle-tendon complex. Taken directly from Weppler and Magnusson, “Skeletal muscles are considered to be viscoelastic. Like solid materials, they demonstrate elasticity by resuming their original length once tensile force is removed. Yet, like liquids, they also behave viscously because their response to tensile force is rate and time dependent.”

Think of viscous like honey. If you tip a bottle of honey over, the honey moves slowly to the stress. Elasticity is like a slinky. It will resist a stretch but quickly return to its original state once the stretch is released.

When a muscle is subjected to a constant stress or stretch, it will slowly elongate in what is known as viscoelastic creep. Due to this, short-term increases in range of motion from stretching is mainly due to viscoelastic changes in the muscle. The idea behind stretching is that moving into an end range of motion and holding that position will increase the flexibility of a muscle-tendon unit and in return increase the range of motion of the worked joints. Overall, the thought process is this—more flexible muscles are able to go into further ranges. This is key for reducing injury, soreness, and tightness. Also, the longer a muscle, the more force it will be able to produce over a longer range of motion, so this will increase performance.

Overall, if you ask someone why they stretch, here’s what most will say:

  • Increased range of motion
  • Injury prevention
  • Enhanced performance
  • Reduced soreness
  • Pleasant feeling

Now let’s take a closer look at each of these reasons for stretching.

Increased range of motion

Stretching does increase short-term flexibility and range of motion. Anybody who has plopped into a stretch can tell you that he's able to achieve an increased range of motion after the stretch than before. As mentioned above, much of this initial increase is due to the viscoelastic properties of muscles. Unfortunately, this increase is transient and the gains quickly disappear. Some studies have shown that flexibility increases may only last between five minutes and one hour, depending on the duration and intensity of the stretch.

Weppler and Magnusson did a review of stretching research and found evidence that seems to suggest that improvements from stretching routines come more from increased stretch tolerance than actual increased muscle lengthening. In other words, when you routinely stretch a muscle, the nervous system becomes more tolerant to the stretch. The central nervous system is more tolerant to allow the body to relax into these deeper positions, so just as you become more tolerant to many external factors in life, you become more tolerant to stretching.

Dedicated, daily stretching protocols do have an increased and more permanent effect on flexibility, but the exact mechanisms aren't 100 percent known. It does seem to be increased tolerance and natural genetics though. Such programs and protocols can be seen in gymnasts and dancers, but these programs require multiple, daily sessions over time to get long-term increases.

Injury prevention

The effects of stretching on injury prevention have been studied quite a bit and the results are varied. Most outcomes from these studies tend to point toward static stretching having a neutral effect. Some studies have even showed the potential for an increased risk of injury from static stretching before activity while a few have shown that static stretching slightly helped to prevent injury.

It can be tough to clarify the results of these studies due to the differences in activity type, duration of the stretch, and age of the subjects. Differences in type of activity, whether speed/power based or aerobic/endurance based, make many of the results cloudy. In addition, the age of the subjects is worth noting due to different responses and states of muscle-tendon units in older versus younger populations. Despite all this, overall stretching won't make you Bruce Willis from Unbreakable nor will it make you Samuel L. Jackson either.

 

Enhanced performance

Most people are aware of the multiple research studies showing that stretching before exercise results in decreased power and speed of the subsequent exercise. While much research does show a correlation between stretching and reduced performance, the designs and applications of these studies vary greatly and may not always be realistic to actual sport or competition.

A study performed by Ogura and colleagues looked at stretch durations for the maximum voluntary contraction (MVC). Three groups—a 30-second stretch group, a 60-second stretch group, and a control group—were tested for flexibility and MVC before and after stretching protocols. They found that both the 30- and 60-second stretching groups produced similar increases in range of motion, but only the 60-second group had a reduction in MVC. The 30-second stretching group didn’t see any differences with the control group in terms of MVC. Other studies have shown similar results—longer duration stretches have a more detrimental effect on performance.

A study by Taylor and colleagues showed that the detrimental power and speed effects seen in static stretching may be erased by performing a sport-specific warm up. Others have recommended performing a dynamic warm up or sport-specific work after static stretching for the best of both worlds. On that same note, many have found that dynamic stretching and drills done alone may improve performance and preparedness for activity.

An interesting study by Haddad and colleagues showed that static stretching may affect speed and power for up to 24 hours. On the other hand, Bradley and colleagues showed that both static and PNF stretching decreased performance in the vertical jump. However, this decrease in performance was fully regained after just a 15-minute wait.

Another interesting study looked at stretching the antagonist muscle to see if it would increase the ability of the agonist to produce force. The thought behind this is that stretching the antagonist will temporarily increase flexibility and relaxation and decrease the output of the antagonist, which will allow the agonist to work through a greater range of motion with less resistance. This advice has been given for a long time. A favorite has been to stretch the hip flexors before a vertical jump or deadlift to allow the glutes and hamstrings to take over the movement. A study by Sandberg and colleagues showed that stretching did indeed live up to this advice, as their results showed an increase in vertical jump height after stretching the hip flexors and dorsiflexors.

The point is that there are many differences in these studies that make interpretation difficult. I admit that I firmly believed static stretching resulted in decreased performance, but after looking deeper, many of these studies are just unrealistic to actual sport or exercise performance. Many of the studies have an athlete perform a static stretch and then immediately pop up and perform a jump or sprint, but how realistic is this? Rarely in actual competition is this the case, and many different factors such as time and technical work usually follow stretching before actual performance.

To sum it up, research seems to suggest that static stretching produces a neutral to slightly negative effect on subsequent exercise, especially if the exercise requires maximal power and speed. Again, this will be affected by a dynamic warm up, “activation” exercises, the duration of the stretch, and the duration until the actual exercise.

Reduced soreness

The clearest aspect of static stretching is that it doesn't reduce muscular soreness. There have been plenty of studies and reviews done to research this aspect, and they all come back the same—static stretching, whether performed before or after activity, doesn't reduce soreness. In fact, in cases of extreme delayed onset muscle soreness (DOMS), static stretching may actually increase soreness and recovery time.

To come to the defense of static stretching, not many modalities truly do help with DOMS. Cheung and colleagues found that massage, cryotherapy, homeopathy, ultrasound, and electrical current modalities all had no overall effect on improving DOMS. We’ve all had DOMS and have used warm ups, stretching, message, and light exercise to reduce it. While these things may help temporarily, we can all attest that the best way to improve DOMS is just time.

Pleasant feelings

This is an interesting aspect of stretching. Many people swear by stretching whether they actually receive benefits or not. Heck, one of the reasons why I like to stretch is because it feels good. I finish and feel a little bit better. This might involve a placebo effect and/or other mental aspects that benefit the individual, but like many things in life, the mental side of things can trump other aspects. Stretching can increase relaxation, improve mood, and calm the body down, so it does have some actual benefits in that sense. So if someone believes that stretching is benefiting them, by all means continue.

Other factors

Duration: This is a very cloudy aspect of stretching with so many different recommendations. Some research has shown that 30-second stretches are just as beneficial as 60-second stretches, but 15-second stretches don’t measure up. Other studies suggest that a stretch as short as 10–15 seconds is sufficient. Still, ask others how to get a more long-term effect and they’ll say that you need durations of 2–5 minutes while others suggest that to get actual tissue change and a more permanent effect, a period of 20–30 minutes is needed.

Overall, I've concluded that if stretching before a workout or for short-term range of motion benefits you, 15–45 seconds will do. However, if you’re looking for a more long-term effect and change, longer holds of 2–5 minutes or longer work best.

Breathing: One aspect of stretching that needs addressed is breathing. Yoga, Pilates, and other such activities have long supported the role of breathing in stretching. Improved breathing patterns such as increased diaphragmatic breathing and focusing on exhalation can trigger relaxation. Focusing on this type of breathing will increase parasympathetic nervous system activity, which will help the body relax and increase the stretch tolerance. Static stretching has been shown to activate the parasympathetic nervous system, which can be great for facilitating rest and recovery. However, on the opposite spectrum, this may contribute to reduced short-term performance after stretching.

Type: The type of stretching protocol performed also plays a role in the effectiveness. Many studies have shown that all types of stretching have positive benefits of acute range of motion gains, but research suggests that types of PNF stretching may be more beneficial than regular static stretching in terms of gaining range of motion. However, to counter this, Azevedo and colleagues showed that PNF stretching had no additional benefit over static stretching. Geez! This is getting hard!

Like many of the previously discussed items, there are studies in support of and rejection of certain types of stretching eliciting a superior benefit. But again, much of this depends on the context of what you're trying to achieve. For increased flexibility, PNF and longer duration static stretches (2–5 minutes) may be superior, but for performance, dynamic stretching may be more beneficial. Different types of stretching will provide different stimuli and invoke different results. Overall, no one type of stretching is the absolute best. Each has a time and place where it can be effective.

Soft tissue: Fascia is a tough connective tissue that surrounds all muscle tissue and provides support and structure. It plays a huge role in the range of motion of a joint and muscle. I’ve heard others say that as much as 40 percent of range of motion potential is related to fascia (don’t quote me on that; I couldn’t find a study to support this claim but have heard it multiple times). Fascia, like stretching, takes a lot of hard work to permanently change. It has been suggested that it takes six months to two years to elicit permanent changes while certain areas may not be able to change at all. Chaudhry and colleagues showed that forces outside physiologic range may be needed to actually stress and deform fascia in certain parts of the body. So regardless of our foam rolling efforts, certain parts may be a lost cause.

A major aspect of fascia is that it’s highly proprioceptive. In fact, there are ten times more sensory nerve endings in fascia than muscle and they are constantly monitoring changes in tension, joint position, rate of movement, and pressure. Thomas Myers, author of Anatomy Trains and an expert on fascia, has said that foam rolling is best for proprioception. It is this proprioception and variety of stresses, positions, and movements that is thought to elicit the best changes and increase the quality of information being sent to muscles and joints.

While fascia gets a lot of publicity, other tissues/structures such as the joint capsule, bone structure, muscle-tendon unit, skin, and hydration all play important roles in a joint's range of motion capabilities. Stretching isn't really a singular approach. In reality, there are many components to improving flexibility and range of motion.

Motor control: Often lack of or loss of range of motion can be a result of instability, weakness, or lack of motor control. The body's main goal is to prevent injury and it will make compensations and restrict movement to protect itself. Often times, a lack of range of motion seen in joints is just the body's protective mechanism. If you can't control or stabilize in certain positions or through certain movements, your body will protect itself and not allow you into those ranges of motion. Here’s a video by Dean Somerset giving you an idea of how this can work.

My thoughts

The biggest problem with the stretching debate is that there doesn't seem to be any middle ground. It’s a really complicated subject with many different opinions, and most are adamantly on one side or the other. I don’t think there is a "one size fits all" approach. There needs to be a variety of methods used to get a complete approach. Personally, I really like the approach that Kelly Starrett from MobilityWod takes—attacking many different components such as soft tissue, joint manipulation, joint capsular, motor control, and PNF and doing something every day for about 10–15 minutes to maintain your body.

I also feel that we need to have goals in place. Why are you looking to improve your range of motion? Is it so you can improve your squat and deadlift mechanics and positions or are you just doing it for the sake of doing it? There needs to be a goal in place and an approach to attack specific needs. Personally, I don’t like to static stretch before certain workouts because I feel that it negatively effects my performance. I feel lethargic, lackadaisical, and slow if I try to perform with any kind of power or speed after static stretching. However, if I’m working with someone where the main goal isn't performance or if we're performing more technical work, I feel that stretching as well as other modalities can definitely help to achieve a better range of motion and position.

Everybody feels and responds differently to stretching. Some people stretch, get hurt, and suck. Others swear by stretching and think that it makes a huge difference. So who am I to tell them not to stretch because it may reduce their power output by five percent? You have to find what works for you and your athletes.

So what are your thoughts on stretching, mobility, and soft tissue work? Do you love it, hate it, or hang out somewhere in the middle? Do you static stretch before working out, maybe after, or maybe not at all? I'd love to hear everybody’s thoughts on this ever complex topic, so please comment and be open to everybody’s unique differences.

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