Stretching is a critical component of many regimens seen in clinical and fitness settings. Whether you’re a person who prefers to stretch before/after your routine, many people will attest to the physiological benefits of stretching. Proponents of stretching believe that it improves performance during exercise and prevents injuries and soreness. Some would go so far as to say that an individual may not be stretching enough when they repeatedly experience pain or injury after their workouts with no signs of improvement. Despite these enduring beliefs, the science behind the benefits of stretching is questionable. For the purposes of this blog post, we will focus on the acute, short-term effects of stretching on performance during exercise.

Three forms of stretching  used in exercise and rehabilitation settings include dynamic stretching, ballistic stretching, and static stretching. Dynamic stretching is a type of stretching which involve fluid-exaggerated movements. Ballistic stretching utilizes fast countermovements. Static stretching involves extending target muscles to a limit point, and maintaining that position for an interval between 10 and 30 seconds. In order to minimize injuries, static stretching is encouraged for non-athletes.

Numerous scientific studies have shown that have shown that static stretching results in an improved joint range of motion  (ROM) and greater flexibility in the muscles targeted by this technique. Conversely, research has also shown that stretching before exercises can result in a lower force output generated in the muscles that are targeted. Compliance is the lengthening of muscle fibers in response to an applied force. According to an article cited by the the National Institute of Health (Anderson, 2005), increased compliance (which occurs a result of stretching) has been linked to a decreased ability to absorb force at rest, whereas decreased compliance results in a muscle being able to withstand higher tension. This is significant because, when sarcomeres are stretched to the point that the actin and myosin filaments do not overlap, the force absorbed is transmitted to the muscle fiber cytoskeleton; resulting in fiber damage (regardless of a muscle’s joint ROM). Thus, compliance may result in decreased performance depending on the type of exercise performed. Another issue that arises related to the use of stretching before exercise is the type of stretching utilized. Science has shown that muscle fibers can experience tension when stretched as little as 20% of their total length1. Thus, it is difficult to establish a universal standard describing correct stretching techniques. In addition, improved joint ROM can be attributable to extraneous factors (such as increased pain tolerance); making the strength of its relationship to stretching highly questionable.

There are a plethora of studies conducted that attempt to quantify the effect of stretching on performance. One study, conducted by researchers at Sahmyook University in 20182 examined the effects of stretching on muscle strength, endurance, and endurance in a non-athletic sample of 13 active collegiate male students. These subjects were separated into three groups: those who did not perform any warm ups before exercise  (NWU), those who performed aerobic warm ups in the form of power walking for ten minutes (AWU) before exercise, and those who performed aerobic warm ups with static stretching for ten minutes (ASU). All three groups performed isokinetic muscle testing. The stretching used in the study consisted of straddling, seated calf stretching, and standing quadriceps stretching for the lower body. Two repetitions of each stretching motion were performed for 20 sec each and the entire stretching program took 5 min to perform. All subjects rested for 1 min after warming up and then underwent isokinetic muscle testing of the knee joints. The sequence of performance of each warm-up exercise was individually randomized. In the successive weeks, each group was tested according to the type of warm-up performed. The testing was conducted for 3 weeks, and all groups were allowed a week to rest in between tests.

In order to quantify the results in each group, a knee extension/flexion isokinetic  dynamometer was used. Participants were asked to extend and flex the knee by exerting their maximum strength as fast as possible while keeping their trunk up against the backrest during the test and to hold onto the handles. The subjects performed the maximal test of four repetitions. Each maximal test was conducted with an angular speed of 60°/sec to measure isokinetic muscle strength and an angular speed of 180°/sec to measure isokinetic muscle power. In addition, the muscle endurance test was conducted with an angular speed of 240°/sec. The exercise was conducted twice prior to testing to familiarize the subjects with the test, thereby achieving optimal results. The subjects were verbally encouraged and allowed to view their torque graphs during testing as a form of visual feedback to increase motivation.  To analyze muscle strength, power and endurance, measurements of the left and right knee joints were divided into each independent variable before data processing was performed. In addition, psychological evaluations in the form of questionnaires were administered to subjects before and after workouts for individuals in all three groups. These assessments utilized a 5-point Likert scale (1, very bad; 2, bad; 3, average; 4, good; 5, very good). The Kruskal–Wallis rank test were used to examine the differences of variables among groups and the Wilcoxon test was used to investigate psychological conditions before and after warm-ups within times in each group. A Mann–Whitney post hoc test was implemented to detect any significant differences in the Kruskal–Wallis test. The significance of all data was established at p ≤0.05. The results from the table have been included in figures attached to this post. The data is shown in the bottom of this point via a hyperlink. 

Based on the results of this experiment, the researchers concluded that there was no significant effect of the type of warm-up activity on performance in any of the tests performed in this study. Shown in Table 2, at 60°/sec (which is an angular speed for rating muscle strength), the NWU showed higher rates for both the extensor and flexor. However, the researchers determined that the difference was not statistically significant Shown in Table 3, at 180°/sec (an angular speed associated with rating muscle power), AWU and ASW groups attained higher rates for the flexor and extensor, respectively, although the difference was not statistically significant. The total work at 240°/sec (which reflects muscle endurance) was higher in ASW for both the flexor and extensor than NWU and AWU, though not statistically significantly. These results are shown in Table 4. In a similar manner to the trends seen when evaluating athletic performance, the individuals in the ASW group marked higher scores on their psychological assessments than the AWU and NWU groups. The results are shown in Table 5. However, the researchers determined that the result were not statistically significant.

Overall, while there appears to be some merit to the psychological benefits of stretching before exercising, its effect on athletic performance remains inconclusive. However, if you find that stretching helps improve your outlook/state-of-mind during the course of your workout, I would highly encourage you to continue your routine.

Questions to Consider

1. Based on the experiment, do you believe that stretching before a workout provides any benefits/advantages towards performance?
2. Does this post affect your views towards stretching?
3. Would you encourage someone seeking to exercise more frequently to stretch before/after their exercises?

References

1. Andersen JC. Stretching before and after exercise: effect on muscle soreness and injury risk. J Athl Train. 2005;40(3):218–220.
2. Park HK, Jung MK, Park E, et al. The effect of warm-ups with stretching on the isokinetic moments of collegiate men. J Exerc Rehabil. 2018;14(1):78–82. Published 2018 Feb 26. doi:10.12965/jer.1835210.605

Results

Anyone who has partaken in any physical activity, whether it is a sport, exercise routine, or just simple around the house chores that require a little more muscle power than normal, has experienced muscle soreness or discomfort.  Generally, when muscles are pushed passed what they are used to (i.e. new exercising routines, increased weight, eccentric exercises) the muscle fibers undergo damage and the body’s response is to add muscle fibers and/or to increase the size of muscle fibers to help increase muscle strength. When talking about sore muscles, it is generally thought the soreness comes from the physical effects of muscle tearing, repairing, and growing from a workout. There is, however, one part of the muscle that plays a role in not only soreness, but also range of motion (flexibility), and muscle performance that not many people know needs special attention: the myofascial tissue.

Figure 1: Skeletal muscle structure through different layers of the muscle. Myofascial tissue lies over the epimysium connective tissue which coats the muscle bundle. The epimysium, perimysium, and endomysium are specialized versions of myofascial tissue.

Different forms of fascia can be found all over the body, from encasing organs, to blood vessels and nerves, to muscle.  Fascial tissue that specifically covers muscle, or myofascial tissue, is a thin, white/transparent connective tissue that covers muscle, bundles, muscle fibers, and the muscle as a whole.  If you have ever picked off the thin white stuff covering parts of a chicken breast while preparing it for dinner, you tore off the myofascial tissue layer. Myofascial tissue is an extremely flexible and strong material, which is made up of elastin fibers, for stretch, and collagen fibers, for strength, that are embedded in a gelatinous ground substance, which reduces friction between the muscle fibers and promotes ease of motion [1]. Considered a “deep fascia,” myofascial tissue is made up of a more compacted weave than other fascia found throughout the body and can modify itself depending on the forces placed on it.   (Figure 2).  Because of this, if there is “trauma” or “injury” to the tissue, it can become out of alignment and

Figure 2: 3D visualization of myofascial tissue (white web like structure) and fascia tissue between the skin and muscle (yellow web like structure). Myofascial tissue can be related to a cotton candy structure that is extremely complex and strong. Retrieved from https://www.myofascialrelease.com/about/definition.aspx

cause trigger or dysfunctional points. These points, most commonly referred to as knots, is when the fibers that make up the tissue gets stuck together, loses its elasticity, and becomes taught [2]. Polly de Mille, R.N., C.S.C.S., director of performance services at the Hospital for Special Surgery in New York City explains in an interview for SELF that it is very similar to getting ice cream in silky smooth hair.  When there are “knots” in the muscle fascia, it limits range of motion, and can trigger immune responses which can ultimately lead to pain and discomfort (cytokines have been shown to cause pain and soreness) [3,4].

Now, what is the best way to heal and prevent muscles from experiencing these knots and discomfort? When talking about getting rid of knots in your body, a massage should be the first thing that comes to mind.  The “hurts so good” mentality of deep massaging muscles to where the patient feels pain and then relief afterwards is a popular desire, though not for everyone. Applying pressure and different forces to the tissue through a massage, or foam roller which we will talk about in a little bit, while moving around the fascia helps to separate and relax the tissue and muscle, allowing it to go back to its natural state.  Effects also include an increase in blood flow, which should help muscles get the proper nutrients to repair. Massaging also releases “feel good” brain chemicals, like endorphins, which basically inhibit pain receptors and overall makes you feel better. A study conducted by Mal-Soon Shin and Yun-Hee Sung induced muscle fatigue on 21 young males and treated 11 of them to massages afterwards while recording surface muscle activation and position of their medial gastrocnemius muscle.  According to their study, massaging increases muscle activation and strength due to a change of structural properties. However, in their discussion, they mention that not all messages are effective, which seems to be a common issue in the argument of whether foam rollers, or self myofascial release in general, works or not [5].

Massages are so great because when another person is working out your muscles, they are not only more accurate in pinpointing the location, but they can also apply more force (remember: collagen is EXTREMELY strong in ratio to its size. Proportionally, it is stronger than steel!).  As great as they are, unless someone at home is a masseuse, it can be costly. Self myofascial release techniques, such as foam rolling, have taken over the exercise world and are now regularly used. Foam rolling is when the user applies pressure to “trigger point” or sore spot before or after a workout by using their body weight to roll against a foam cylinder. Though it feels good, does it actually work?

Research has proven that foam rolling is great for warming up muscles and increasing range of motion and flexibility, but the verdict is still out on decreasing muscle soreness.  Though the mechanism behind foam rolling is not exactly known, there is great evidence that it does work on some type of level, whether it is physical or just simply mental. In a systematic literature review of research on using a foam roller before and after workouts, Scott W. Cheatham identified different scientific articles that were critically appraised with trusted conclusions.  From these articles, he identified five studies on the effects of foam rolling and range of motion before exercising. All of these studies resulted with an increase in stretching or range in motion in test subjects [6]. It is common knowledge to stretch before a workout or game to help “warm up” the muscles so that they’re are more flexible, which helps prevent injury and soreness. It is also speculated that rolling out could create a friction that literally heats up the fascia and muscle, making it more flexible and the typical “loose” feeling [2].  After a workout, however, there is a preconception that rolling out will help with delayed onset muscle soreness and pain in general. In this literature review, Cheatham identifies two different journals that conclude that foam rolling does reduce pain, but since the mechanism behind it is still unknown, how much can we trust? In the same SELF article as mentioned previously, Lewis J. Macgregor, Ph.D., an exercise physiologist and lead author of the University of Stirling confirms foam rolling does help increase blood flow, which in turn promotes muscle recovery, but foam rolling does not actually help with myofascial release. Since the collagen in the fascia is so strong, it is argued using your body weight to roll out is not enough. Instead, the pressure of rolling stimulates nerve receptors, which sends the same “hurts so good” feeling to your brain that is then perceived as loosening up the muscle, when really it is not happening.

Overall, foam rolling and myofascial release is an effective way to warm up your muscles and stretch them out before a workout and to help stimulate more blood flow post workout, just don’t get your hopes up about avoiding soreness! Increasing range of motion and flexibility before a workout is a great step to ease muscle soreness, but foam rolling alone is not the answer.  The verdict is still out on the mechanism behind the effects of myofascial release on a cellular level, but hey, if it feels good, why not!

If you’re interested, here is a video of foam rolling techniques because like anything, it’s not effective if you don’t do it properly.

https://www.youtube.com/watch?v=WCj1dvTwOF0

Questions to consider:

Is it worth it to foam roll or stretch in general before physical activity?

Is myofascial release something to think about daily and not just dealing with exercising?

Do you think foam rolling has a placebo effect or is it both systems (nervous and skeletomuscular) working together?

Do you think foam rolling is just another exercising fad?

Would adding heat be beneficial? Or a waste of time?

Sources:

1. Shah, S., & Bhalara, A. (2012). Myofascial Release. International Journal of Health Sciences and Research,2(2), 69-77.
2. Fetters, K. A. (2018, July 21). Here’s What Foam Rolling Is Actually Doing When It Hurts So Good. Retrieved April 12, 2019, from https://www.self.com/story/what-foam-rolling-is-actually-doing-when-it-hurts-so-good
3. Grosman-Rimon, L., Parkinson, W., Upadhye, S., Clarke, H., Katz, J., Flannery, J., … Kumbhare, D. (2016). Circulating biomarkers in acute myofascial pain: A case-control study. Medicine, 95(37), e4650. doi:10.1097/MD.0000000000004650
4. Zhang, J. M., & An, J. (2007). Cytokines, inflammation, and pain. International anesthesiology clinics, 45(2), 27–37. doi:10.1097/AIA.0b013e318034194e
5. Shin, M., & Sung, Y. (2015). Effects of Massage on Muscular Strength and Proprioception After Exercise-Induced Muscle Damage. Journal of Strength and Conditioning Research,29(8), 2255-2260. doi:10.1519/jsc.0000000000000688
6. Cheatham, S. W., Kolber, M. J., Cain, M., & Lee, M. (2015). THE EFFECTS OF SELF-MYOFASCIAL RELEASE USING A FOAM ROLL OR ROLLER MASSAGER ON JOINT RANGE OF MOTION, MUSCLE RECOVERY, AND PERFORMANCE: A SYSTEMATIC REVIEW. International journal of sports physical therapy, 10(6), 827–838.