Static stretching is a common way to loosen tight muscles but recently self- myofascial release using a foam roller has become popular. Currently, there is significantly more literature that looks at the chronic effects of self-myofascial release, not on the potential acute effects (MacDonald et al., 2013). Another issue is that most studies to date (Blackburn et al., 2012; Grieve et al., 1997; Kuruma et al., 2013; MacDonal et al., 2013; Spernoga et al., 2001) have only examined range of motion measured with a goniometer. The issue with only measuring range of motion is that it yields no information about the material property of the muscle by not addressing the stiffness component of the muscle. An increase in range of motion could be due to an increased stretch tolerance, not a change in muscle property, which is why stiffness data is paramount. ROM is also hard to measure because of a subjective end-point at which the goniometer reading is recorded due to the subject’s stretch tolerance (Magnusson, 1998). There is also no current literature that has compared the effects of static stretching and self-myofascial release on muscle stiffness or range of motion using an isokinetic dynamometer (MacDonald et al., 2013). Therefore, the purpose of this study was to compare the effectiveness of self-myofascial release and static stretching in reducing stiffness and increasing range of motion in the calf muscle of apparently healthy and recreationally active individuals.
Range of Motion
There was no significant difference between static stretching and self- myofascial release using a foam roller for maximum ROM even though both
methods increased ROM. Similar results were found where there was an increased range of motion post long term static stretching in the Magnusson (1998) study; however, Magnusson attributed the increase to an increase in stretch tolerance, not a change in muscle properties (Magnusson, 1998). Though this conclusion was draw, data on the property of the muscles (i.e. stiffness) would be needed to support the claim that the material properties of the muscle were not affected.
Kuruma et al. (2012) found that active and passive range of motion were increased after stretching and self-myofascial release. Kuruma and colleagues concluded that increases were due to realignment of the fascia in the quadriceps and hamstrings to allow for a greater degree of knee flexion. The researchers did not compare the change in range of motion between the interventions, which would have been an interesting comparison. In another study, MacDonald et al. (2013) found that foam rolling the quadriceps resulted in increased range of motion at the knee joint, without decreasing force production. Knee joint range of motion was measured at 2 minutes and 10 minutes post the foam rolling intervention, which consisted of two, 1-minute sessions of rolling the quadriceps with one minute of rest in between sessions. The same protocol was used in the current study, though MacDonald did not compare foam rolling to static stretching techniques. MacDonald and colleagues also determined that after foam rolling there was no longer a
rolling is a method of stretching that appears to not negatively affect performance. Furthermore, MacDonald and colleagues attributed the increase in ROM to a change in the thixotropic property of the muscle, due to foam rolling warming up the fascia, causing it to become more fluid like, and breaking down scar tissue. Duration and force of the stress application were two factors speculated by MacDonald and colleagues that were important to the changes observed in the muscle. Although the shorter duration of 2 minutes of stretching was generally lower than in similar studies, the force of the subjects body weight was great enough to still cause the fascia to become more gel like. MacDonald and colleagues also recommended, based on the results of the study, that static stretching should be eliminated from warm ups due to the damage it induces of sarcomeres and the subsequent decrease in muscle force production. Since self-myofascial release changes the properties of the muscle rather than placing pressure on the origin and insertion points of the muscle like static stretching, it does not damage the sarcomeres and therefore also does not negatively affect force production. This means that since static stretching and foam rolling appeared to have had similar affects on range of motion and stiffness in the current study, it can be speculated that it would be better to choose foam rolling as a warm up strategy over static stretching, as there is not a decrease in force
production and it is less likely to damage sarcomeres. However, with the goal of promoting muscle tension alleviation and increasing ROM in tight muscles post training or competition, the current study showed that either static stretching or SMR using the foam roller produced similar effects.
Stiffness
For the purposes of this study, stiffness was defined as the change in torque divided by change in position, the relationship between stress and strain. There was no significant difference between static stretching and foam rolling for stiffness at 15˚ or stiffness at 80% of maximum range of motion. In earlier research, Magnusson (1998) found that a repeated static stretching caused a decrease in muscle stiffness, however, results only lasted an hour. Magnusson attributed the brevity of the response to the increase in tolerance, not a change in the material property of the muscle; however, it was not demonstrated in Magnusson’s study that a decrease in resistance could be attained at the same joint angle or the same resistance at a larger joint angle; if this could be demonstrated, it would be possible to concluded that a change in material property of the muscle was the cause of the decrease in muscle stiffness. In the current study, it was hypothesized that SMR using a foam roller would produce a greater decrease in muscle stiffness and even though no significant difference between groups was observed, it approached significance (p=0.06) at 15˚. Though not statistically significance, the difference in means between the change seen with static stretching (0.025 Nm·deg-1) and SMR (0.366 Nm·deg-1) are of clinical relevance because a greater decrease in stiffness occurred using the foam roller than static stretching. Likely there was less of a difference at 80% of maximum ROM because at that point, the muscle is stretched almost to it’s full extent, which would cause it to be stiffer than at 15 degrees.
Gajdosik et al. (2004) found that older women have increased calf muscle stiffness, likely due to limited range of motion. Gajdosik and colleagues argued that
if subjects were initially screened for limited dorsiflexion, stretching and foam rolling may make more of a difference for subjects with limited ROM than for the general population. Kubo et al. (2001) found that static stretching led to decreased stiffness by increasing the elasticity of the tendon structures. Instead of directly measuring stiffness, the researchers used ultrasonography to look at the elongation of the tendon and aponeurosis of the medial gastrocnemius, which could cause differences in results. Kubo and colleagues concluded that tendons and muscles are quite compliant and that the type of stretch may be a key factor in whether or not a decrease in stiffness is found. The researchers also suggested that their results indicate changes in both series and parallel elastic components in response to stretching. In another study examining strategies for decreasing muscle stiffness, Kuruma et al. (2012) did not find significant changes in stiffness before and after the stretching and self-myofascial release interventions. Each intervention lasted 8 minutes although the protocol used in the study did not provide detailed
information, hindering the readers’ ability to make conclusions on the effects of the intervention on reducing muscle stiffness. The way the subjects stretched or their method of myofascial release could have been the reason the researchers did not find significant results for stiffness. Stiffness was measured with a durometer instead of an isokinetic dynamometer, which could potentially add to the non- significant findings. To further the science and fill the gap on measuring muscle stiffness, one of the potential issues when evaluating muscle stiffness, the current study used isokinetic measurements. Contrary to Kuruma and colleagues, significant improvements in muscle stiffness were observed from pre to post interventions.
Therefore, the way stiffness is measured in an important factor to consider in future investigations. Some previous methods of assessing muscle stiffness may not be sensitive enough to identify potential changes in muscle stiffness. Consequently, based on the results of the current study, the use of an isokinetic dynamometer is recommended.
The protocol followed for foam rolling may have impacted results. In the current study, the protocol was modeled after the one used by MacDonald and colleagues (2013). Subjects performed a total of two minutes of foam rolling with one minute of rest in between sessions of foam rolling. Subjects were instructed to roll down the right calf slowly, 3-4 times within the minute. In this technique the foam roller is continuously moving, as opposed in other techniques where it is held still on a restriction for a given length of time. Blackburn and colleagues (2012) instructed subjects to foam roll for a total of 5 minutes, however, the foam roller was not moving continuously. During the first minute, subjects performed a general scan of the muscle and the second minute was a targeted scan of the lateral and medial heads of the gastrocnemius. During the next two minutes, subjects held the foam roller on restrictions they had found during the scan. Pressure was applied to the restriction for 30 seconds, then the foam roller was moved to the next
restriction, and so on. The last minute was another general scan of the muscle. Blackburn and colleagues could not analyze the data on stiffness, so it is unknown as to whether this method is superior to the continuous rolling method used in the current study.
Summary
The purpose of this study was to determine if static stretching or self- myofascial release was more effective at decreasing muscle stiffness and range of motion in the calf muscle. An isokinetic dynamometer was used to measure both stiffness and ROM before and after the stretching interventions. Each subject completed two minutes of static stretching on an incline board and two minutes of foam rolling on separate days. Results showed no significant difference between the two stretching techniques, however, an increase in ROM and reduction in muscle stiffness were observed using static stretching and SMR with a foam roller. Therefore, it was concluded that both static stretching and foam rolling increase range of motion and decrease muscle stiffness similarly.
Recommendations for Future Research
Similar study with athletes (football players) as subjects. Athletes are more likely to have fascial restrictions than the general population due to exercise. Similar study with gymnasts as subjects. Gymnastics are flexible, so they may
benefit more from foam rolling than static stretching.
Similar study with individuals with restricted ROM, who would most benefit from a stretching intervention.
Potentially adding a third group where a combination of static stretching and self-myofascial release could be compared to the two techniques in isolation. Explore different volumes of the intervention; the amount of training that is
necessary for the self-myofascial release to be as effective as possible.
Modify self-myofascial release protocol to hold the foam roller on restrictions rather than continuous rolling.
Similar study protocol with a different muscle group other than calves, such as hamstrings.
Similar study with stiffness and ROM measurements taken at various time intervals after stretching intervention to see if static stretching of self- myofascial release leads to longer lasting results.
Add EMG measurements prior to assessing ROM and stiffness to ensure that subjects’ muscles are fully relaxed and not producing unnecessary tension that could skew results.
To begin investigating the chronic effects of the two interventions since an acute bout of stretching may not be enough to produce clinically significant alterations on stiffness of the muscle.
If the dose-response relationship can be determined, looking at the amount of force and time of myofascial release needed to cause the most desirable changes in the fascia allowing for greater release of stiffness.
Conclusion
Static stretching and self-myofascial release via foam roller are both effective stretching techniques in increasing range of motion and decreasing muscle stiffness. Both interventions yielded similar results, so neither method appears to be superior when used as techniques to increase ROM and alleviate muscle stiffness. Therefore, based on the individual preference, static stretching and SMR could be used
interchangeably. Since previous research has shown negative effects associated with static stretching, such as decreased muscle force production and damage to
sarcomeres, self-myofascial release would likely be a better choice of stretching technique prior to training or competition.