Written by Samuel Biesack
Stretching before exercise is a necessity, or so most people think. Often practiced under the pretense that doing so will prevent injury, everyone from bodybuilders to professional athletes often stretch before performing exercise.
However, the lines defining the truth behind pre-workout stretching are often blurred with little evidence suggesting doing so prevents injury and further, even some data indicating stretching decreases performance when weight training.
So, does pre-workout stretching lead to decreased performance?
Stretching & Injury Prevention
Studying stretching, as an injury prevention measure is difficult. In order to have real world relevance, researchers have to find a population and stretching protocol that is representative of the majority of athletes.
Additionally, in order to determine that the stretching protocol was effective, researchers need to bank on some participants getting injured. If you haven’t guessed, that’s not exactly a recipe for a strong conclusion.
So what exactly does the current research say about pre workout stretching for injury prevention?
Studies such as that by Behm et al., in 2016 showed no measurable difference in overall injury rates when comparing static stretching and proprioceptive neuromuscular facilitation (PNF) stretching which is the gold standard of partner-assisted stretching.
The nature of the practice simply makes it too difficult to find meaningful results.
Stretching & Performance
The effect that stretching has on athletic performance is a completely different story. Contrary to popular belief, pre workout stretching actually decreases performance across a wide range of events. Everywhere from strength to endurance, pre workout stretching time and again has been shown to be a detriment.
Interestingly, there are a number of reasons stretching can decrease performance.
☐ Length of the Muscle
Within the muscle, the contractile components, actin and myosin are what actually make the muscle shorten, or contract. In order to do so, these two components overlap, attach onto each other and slide. Basically, these two components pull on each other and shorten, causing the muscle to shorten.
When you stretch and increase the length of the muscle, the overlap-ness of these components is reduced. In essence, they have a hard time lining up, attaching to each other, and make it more difficult to contract the muscle.
This can have a myriad of negative effects if you are trying to contract the muscle quickly and forcefully.
☐ Elastic Energy
Consider a rubber band that is stretched. The further the rubber band is stretched, the more powerful the recoil when it is released. This is because by stretching the band you are creating what is called elastic energy. The same thing happens in the muscle.
During movements like the squat or running, you are creating elastic energy each time you lengthen the muscle. And this elastic energy is used to contract the muscle, making you more powerful.
When you stretch before exercise, you actually decrease the amount of elastic energy that can be stored. See, there is a relationship between the length of the muscle and the amount of elastic energy it can store.
By lengthening the muscle as a result of stretching, you decrease the amount of elastic energy that is stored, and thus, the amount of elastic energy that can be used.
These aren’t the only negative effects, but you get the picture. Stretching reduces performance. In fact, some studies have even shown a decrease in strength of up to 30%!
Range of Motion
Fortunately, some studies have shown that pre workout stretching does in fact increase range of motion for a short period of time (Behm, 2016). Further, increasing your range of motion may have many different effects such as reducing your risk of injury, as well as reducing pain, which may culminate in the ability to produce more strength.
The ability to move better due to increased range of motion could help overcome the potential loss in performance, brought on by stretching in the first place.
Take Home Message
If you fall under the category of needing to stretch in order to increase range of motion, there are ways to increase this range of motion and minimize the potential negative effects of stretching. The data seems to indicate that the big decreases in performance come when stretches are held for longer than 45 seconds (Simic, 2012).
To be safe, keeping static stretches during the pre workout period to 30 seconds or less is likely optimal for increasing range of motion, acutely and minimizing potential decreases in performance.
Considering the nature of studies on stretching for injury prevention, there isn’t a lot of strong evidence on either side. Consider using discretion when stretching. If you believe that stretching is necessary, you should continue to do so. Just keep in mind that it could be decreasing performance.