Author: Nolan Wright
Introduction:
Throughout the average American student’s primary education, from as early as elementary school to as late as high school, PE class was required for every student. At the beginning of class, before we participated in whatever activity our PE teacher had planned for us, she would lead us in stretches because we were taught that stretching would prevent injuries during class. While this is a well-known truth, I do not remember our gym teacher teaching us about how different types of stretching can have different impacts on our athletic performance. I did not even know that there were multiple types of stretches! The reality is that stretches can be divided into two groups, static and dynamic stretches, and your performance and flexibility will depend on which type of stretches you decide to do before your exercise.
The Ups and Down of Static Stretching:
To begin, let us go a little more in depth on static stretching. A static stretch can be defined as a stretch where one muscle or small section of muscles is isolated in a push or pull movement and held for a certain amount of time (Stretching Truths). A common static stretch that you may be familiar with is the seated hamstring stretch. For this stretch, while sitting on the ground, you extend your legs in front of you, then try to touch your toes without bending your legs. Researchers have found that while there are benefits to engaging in static stretching such as increasing one’s range of motion (Behm and Chaouachi 2011) and flexibility (Osullivan et al. 2009), there have been other findings that show performing static stretches before exercise can lead to performance impairments (Behm and Chauchi 2011, Chaouachi et al. 2010, Mcmillian et al. 2006). According to the research, there are two main reasons that experimenters believe to be the connection between performing static stretches and the impaired athletic performance.
The first potential reason that static stretching could cause an impairment to performance is that repeated stretches could reduce neural activation of motor units available to contract one’s muscles (McMillian 2006). For those of you that are not as familiar with human physiology, a motor unit consists of a specialized ‘motor’ neuron that sends signals from the brain to the muscle fibers, allowing them to contract (McArdle et al. 2016). During exercise, as the intensity of the exercise increases, your body needs more force in order to do these harder exercises. In order to produce more force, your body will begin to activate more and more motor units on the muscles being used during the exercise. The more motor units that are activated, there will be an increase in the number of muscle fibers contracting. This process will then cause your muscles to produce stronger contractions. On the upper end of exercise intensity, after the maximum amount of motor units have been activated, your nervous system will continuously send activation signals to all the motor units already contracting your muscle fibers in order to keep producing the force necessary to perform the exercise. If neural activation is reduced from static stretching, there would be less signals to activate the necessary amount of motor units to contract one’s muscles, thus being unable to produce the required force for the exercise.
The second potential reason behind static stretching’s connection to reduced performance is that, by elongating one’s muscles, you may involuntarily activate your “neuromuscular inhibitory response” (Reynolds 2019). In order to prevent overstretching of a muscle, the neuromuscular inhibitory response will trigger, which in turn tightens the muscle. If your muscles are overtightened as a result from preventing overstretching, the amount of force your muscles could produce could decrease upwards of thirty percent for a maximum of thirty minutes (Reynolds 2019).
Dynamic Stretching Seen as Superior:
On the other end of the stretching spectrum, dynamic stretching utilizes a full range of body movements rather that strictly muscle isolation (Reynolds 2019), as seen in static stretching. A common dynamic stretch is arm circles. While standing with feet shoulder-width apart, you extend your arms out at your sides and move them in a small, or larger, circular motion. From a literature review compiled by David Behm and Anis Chaouachi (2011), researchers who explored the short-term effects of dynamic stretching on athletic performance found that dynamic stretching had either no effect on performance or an increase in performance, unlike subjects who engaged in static stretching. In an experiment that compared how both static and dynamic stretching styles impacted performance in T-shuttle run, underhand medicine ball distance throw, and 5-step jump, the dynamic stretchers outperformed the static stretching group and no stretching group in all three trials (McMillian et al. 2006). There are several reasons cited across various literature sources regarding how dynamic stretching increases performance for a short period of time. While most factors are related to a change in temperature caused from stretching, other reasons behind the positive impacts of dynamic stretching include decreasing stiffness in muscles and joints; faster neural signals to muscles; and an increase in not only how fast you can produce force in your muscles, but how much force you can produce as well (McMillian et al. 2006).
Is Dynamic Stretching Superior to Static Stretching?
So far, it would seem that unless you are looking to increase your flexibility and range of motion, static stretching should be avoided at all cost in favor of dynamic stretching, but there has been some research that showed no impairment to performance after subjects engaged in static stretching, but there is a catch. Even though Chaouachi et al. (2010) found no significant decrease in performance of jumping, sprinting, and agility tasks, the subjects for the experiment consisted of male students that were all highly trained athletes. This led experimenters to conclude that the reason no negative effects were seen in their subjects, even though they all participated in static stretching, was due to the highly-trained nature of these athletes. Based on what we already know about how prior static stretching negatively impacts athletic performance, the secret behind an athlete’s resistance could be hidden in their motor units. Due to the intense nature of an elite athlete’s exercise program, their nervous system would have to constantly be sending signals to motor units in order to produce the force needed for their exercise. Since their nervous system has to work so hard for multiple times a week during their training, it seems reasonable that stretching of any kind would not cause any negative effects in an elite athlete’s performance.
Recommendations
So, in the end, is one stretching style superior to the other? The answer is yes, but it depends on a number of variables. If you are trying to boost your athletic performance, I would recommend dynamic stretches over static stretches (unless you are a trained athlete, of course). On the other hand, if you are simply trying to increase your flexibility and range of motion, performing simple static stretches will do the trick.
Sources
- Behm, D. G., & Chaouachi, A. (2011). A review of the acute effects of static and dynamic stretching on performance. European Journal of Applied Physiology, 111(11), 2633–2651. doi: 10.1007/s00421-011-1879-2
- Chaouachi, A., Castagna, C., Chtara, M., Brughelli, M., Turki, O., Galy, O., … Behm, D. G. (2010). Effect of Warm-Ups Involving Static or Dynamic Stretching on Agility, Sprinting, and Jumping Performance in Trained Individuals. Journal of Strength and Conditioning Research, 24(8), 2001–2011. doi: 10.1519/jsc.0b013e3181aeb181
- McArdle, W. D., Katch, F. I., & Katch, V. L. (2016). Essentials of exercise physiology. Philadelphia, Pa.: Wolters Kluwer.
- Mcmillian, D. J., Moore, J. H., Hatler, B. S., & Taylor, D. C. (2006). Dynamic vs. Static-Stretching Warm Up: The Effect on Power and Agility Performance. The Journal of Strength and Conditioning Research, 20(3), 492. doi: 10.1519/18205.1
- Osullivan, K., Murray, E., & Sainsbury, D. (2009). The effect of warm-up, static stretching and dynamic stretching on hamstring flexibility in previously injured subjects. BMC Musculoskeletal Disorders, 10(1). doi: 10.1186/1471-2474-10-37
- Reynolds, G. (2019, June 11). The 10 Biggest Fitness Myths. Retrieved from https://www.outsideonline.com/1927761/10-biggest-fitness-myths.
- Stretching Truths. (2019, March 13). Retrieved from https://www.outsideonline.com/1828991/stretching-truths.