Foam rolling and self-myofascial release

Foam rolling is the most popular form of self-myofascial release, which is the type of myofascial release that is performed by the individual on themselves rather than by a practitioner.

Self-myofascial release is probably better termed “tool-assisted self-manual therapy” because of current uncertainty regarding its mechanisms of action.

Self-myofascial release causes an increase in short-term flexibility that lasts for >10 minutes but does not affect athletic performance acutely. Self-myofascial release may also be able to increase flexibility long-term, in programs of >2 weeks.

Self-myofascial release may reduce perceived soreness and increase pressure pain threshold as a result of DOMS during the 48 hours following damaging exercise.

CONTENTS

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Summary

Background

Acute effects on flexibility

Acute effects on athletic performance

Acute effects on delayed onset muscle soreness

Chronic effects on flexibility

Other effects

Mechanisms

References

SUMMARY

PURPOSE

This section provides the summary of research findings into foam rolling and other similar forms of self-myofascial release. 

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SUMMARY EVIDENCE FOR FOAM ROLLING

Flexibility – Self-myofascial release, including foam rolling, causes an increase in short-term flexibility that lasts for >10 minutes. It is currently not possible to identify any dose-response effect

Athletic performance – Self-myofascial release, including foam rolling, does not affect athletic performance

Muscle soreness – Self-myofascial release may reduce perceived soreness and increase pressure pain threshold as a result of DOMS during the 48 hours following damaging exercise

Flexibility – Self-myofascial release may be able to increase flexibility long-term, in programs of >2 weeks

Other effects – There are preliminary indications that self-myofascial release might potentially improve recovery by modulating parasympathetic nervous system activity

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BACKGROUND TO FOAM ROLLING

PURPOSE

This section explores the definitions of foam rolling and self-myofascial release, as well as the definitions of the key underlying concepts of fascia, myofascial release, and myofascial trigger points.

DEFINITIONS

Introduction

Foam rolling is a form of self-myofascial release therapy, which is itself a type of myofascial release therapy, which is a form of manual therapy. Whether the term “self-myofascial release” correctly describes the mechanisms of this type of therapy is currently unclear and a better term might be “tool assisted self-manual therapy” or “tool assisted self-massage” in order to avoid confusion. However, given that the term “self-myofascial release” is already in widespread use, it has been used in this review. For further discussion of this issue, see the mechanisms section (read more).

Nevertheless, in order to provide definitions of self-myofascial release, we first need good definitions of the underlying concepts of fascia, myofascial release therapy and myofascial trigger points. However, there are two major challenges with providing these good definitions. Firstly, it is unclear to what extent fascia is related to the effects of foam rolling, self-myofascial release therapy, and myofascial release therapy more generally. Secondly, the field of fascia research is quite young and researchers are still very much feeling their way through an extremely complex and difficult area. These challenges make good definitions of any of these terms very hard to provide. In this section, we discuss the definitions currently in use by researchers.

Fascia

According to the standard definition provided by the Journal of Bodywork and Movement Therapies (LeMoon, 2008), fascia is “the soft tissue component of the connective tissue system that both penetrates and surrounds muscles, bones, organs, nerves, blood vessels and other structures and extends from head to toe, from front to back, and from surface to deep in an uninterrupted, three-dimensional web”. This definition was picked up and enhanced in the review by Findlay (2009), who introduced fascia as “the soft-tissue component of the connective tissue system that permeates the human body, forming a continuous, whole-body, three-dimensional matrix of structural support. It interpenetrates and surrounds all organs, muscles, bones, and nerve fibers, creating a unique environment for body systems functioning.”

In a more recent discussion of the problem of fascial nomenclature, Schleip et al. (2012) defined fascia as “the soft tissue component of the connective tissue system that permeates the human body (and) that is part of a body wide tensional force transmission system.” Indeed, Huijing and Jaspers (2005) observed that since longitudinal mechanical loading in vitro does not cause the same adaptations as similar mechanical loading in vivo, force transmission through myofascial connections may be important in the process of muscular hypertrophy.

However, Schleip et al. (2012) also noted that there has been significant disagreement in respect of the exact definition of fascia. This lack of agreement has caused a great deal of confusion regarding and a breakdown in communication between researchers working in different fields and geographies as well as between researchers and clinicians. Consequently, it has been noted that different anatomy textbooks and articles referring to fascia continue to do so on the basis of slightly different definitions (see review by Schleip et al. 2012).

Myofascial release

Myofascial release is the term given to a specific form of manual therapy that is intended to have an effect on fascia, although whether any effect is exerted on fascia by this technique or whether it exerts its effects through other mechanisms is as yet unknown. It is thought that the term myofascial release was first coined in 1981 by Chila, Peckham and Manheim, in a course titled ‘‘Myofascial Release’’ at Michigan State University (see review by McKenney et al. 2013) in reference to a specific form of manual therapy. It was not widely discussed, however, until it was the subject of a preliminary review by Mark Barnes (Barnes, 1997), where it was defined as “a hands-on soft tissue technique that facilitates a stretch into the restricted fascia” with the result that “after a few releases the tissue will become softer and more pliable”. Some researchers consider this review by Barnes to be the first use of the term in the literature (e.g. MacDonald et al. 2013).

In recent years, the designation myofascial release has become a more broad term covering a wide variety of techniques, including osteopathic soft-tissue techniques, structural integration (Rolfing), massage, instrument-assisted fascial release, Graston technique, trigger point release and many others (see review by Simmonds, 2012). Now, most practitioners hold that the technique of myofascial release is intended to address localized tightness in the fascia, although the literature often seems to be slightly confusing regarding whether muscle tissue, fascia itself or a combination of both is intended being treated. Nevertheless, it is believed that muscle and/or fascia may under some circumstances tighten (by some as yet undetermined mechanism) and what was previously a pain free range-of-motion may now cause pain and blood flow restrictions (see review by Findley et al. 2012). It is suggested that myofascial release can rectify this problem.

Myofascial trigger points

The sensations of pain that are caused by localized tightness in the fascia are generally referred to as “myofascial pain syndrome” and the localized tightness itself is thought to be caused by myofascial trigger points. Myofascial trigger points are more usually defined as “tender spots in discrete, taut bands of hardened muscle that produce local and referred pain” (see review by Bron and Dommerholt, 2012). As above, there again appears to be some slight confusion about the terminology, as it is not immediately clear here on the face of it whether fascia, muscle fibers or the combined unit (just as we often refer to muscle-tendon units, for example) are being described.

It should be noted that research into myofascial trigger points has proved problematic. Tough et al. (2007) reviewed the literature and found that the diagnostic criteria used by clinicians and researchers to identify myofascial trigger points varied extremely widely, with 19 different criteria being identified. However, they found no consistent pattern to the choice of the diagnostic criteria or their combinations. Additionally, Lucas et al. (2009) carried out a systematic review of the literature regarding the reliability of physical examination for the diagnosis of myofascial trigger points. They identified 9 low quality studies and found that reliability varied substantially from low (< 0.40) to excellent (> 0.75), although the exact range of reliability measures varied from depending on the measurement being taken.

Self-myofascial release

Self-myofascial release is simply that category of myofascial release techniques that are performed by the individual themselves rather than by a clinician and that involve the use of a tool, such as a foam roller or roller massager. However, given the lack of evidence connecting myofascial release and self-myofascial release to changes in fascia, some researchers have proposed that a better term for self-myofascial release would be self-manual therapy. Whether the term “self-manual therapy” is accurate enough to differentiate between true self-massage with the hands and the techniques commonly used in self-myofascial release that involve tools (such as roller massagers, baseballs, and foam rollers) is unclear. Consequently, a better term might be “tool assisted self-manual therapy” or “tool assisted self-massage” in order to avoid confusion. Nevertheless, it seems likely that many of the effects of self-myofascial release will be similar to those of myofascial release and that they will probably share the same mechanisms.

Foam rolling

Foam rolling is a common form of self-myofascial release that is often used by fitness enthusiasts and athletes prior to a workout with a view to improving flexibility or after a workout with a view to reducing muscle soreness and promoting quicker recovery. However, available research has until recently been very limited in respect of both of these effects.

CONCLUSIONS REGARDING FOAM ROLLING

Fascia is the soft tissue component of the connective tissue system that permeates the human body and that is part of a body wide tensional force transmission system.

Myofascial release is a form of manual therapy that is intended to address localized tightness in the fascia that is currently causing pain (and potentially blood flow restriction).

Myofascial trigger points are thought to be tender spots in discrete, taut bands of hardened muscle that may produce pain.

Self-myofascial release is simply that category of myofascial release techniques that are performed by the individual themselves rather than by a clinician. It should probably be called “tool-assisted self-manual therapy”.

Foam rolling is a common form of self- myofascial release that is often used by fitness enthusiasts and athletes prior to a workout with a view to improving flexibility or after a workout with a view to reducing muscle soreness and promoting quicker recovery.

 

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ACUTE EFFECTS OF FOAM ROLLING ON FLEXIBILITY

PURPOSE

This section sets out a summary of the research into the short-term (acute) effects on flexibility of foam rolling and other, similar types of self-myofascial release.

BACKGROUND

Definitions

For the definitions of fascia, self-myofascial release, and foam rolling, see the background section.

Popular usage

Although stretching has historically been the most common method for increasing flexibility immediately before a training session (i.e. acutely), some coaches are now beginning to make use of foam rolling either as an additive measure or as a replacement. Increasing flexibility can be required immediately prior to either resistance training or sports practice sessions, in order to ensure that the required joint ranges of motion (ROM) can be achieved.

Static stretching has historically been the most popular training method for increasing joint ROM, both in the short-term (i.e. acutely) and in the long-term (i.e chronically). Indeed, research has supported the use of static stretching for increasing joint ROM (see reviews by Decoster et al. 2005; Radford et al. 2006). Unfortunately, static stretching also appears to produce undesirable short-term reductions in athletic performance, although such reductions may be only pronounced when stretches are of long duration (>45 seconds) (see reviews by Behm and Chaouachi, 2011; Kay and Blazevich, 2012; Simic et al. 2013; Kallerud and Gleeson, 2013). Therefore, if foam rolling can be used as a replacement training method for increasing flexibility immediately prior to training, then it may be of use to strength coaches and sports coaches alike.

Literature usage

Since foam rolling has been presented as a suitable alternative to static stretching for increasing joint ROM in the short-term (acutely), researchers have been interested to understand whether foam rolling can produce similar improvements in joint ROM. Therefore, many studies not only assess the extent to which foam rolling can produce acute increases in joint ROM relative to a baseline but also relative to a static stretching comparative group.

ACUTE EFFECTS OF FOAM ROLLING ON FLEXIBILITY

Selection criteria

The following criteria were applied:

Population – any

Intervention – any self-myofascial release technique

Comparator – either resting control group or baseline

Outcome – any measurement of joint ROM taken acutely post-treatment

Results

The following 10 studies were identified (click to read): Mikesky (2002), MacDonald (2013), Sullivan (2013), Howe (2013), Roylance (2013), Halperin (2014), Jay (2014), Button (2014), Peacock (2014), Grieve (2015). Of these 10 studies, 6 reported significant increases in flexibility while the remainder reported no effects. Self-myofascial release therefore appears to increase flexibility acutely.

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TIME COURSE OF ACUTE EFFECTS OF FOAM ROLLING ON FLEXIBILITY

Selection criteria

The following criteria were applied:

Population – any

Intervention – any self-myofascial release technique

Comparator – several time points acutely post-treatment

Outcome – any measurement of joint ROM acutely post-treatment

Results

The following 3 studies were identified (click to read): MacDonald (2013), Halperin (2014), Jay (2014). These studies have generally reported improvements in flexibility up to and including 10 minutes but no longer. Self-myofascial release therefore appears to increase flexibility acutely up to 10 minutes post-treatment.

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DOSE-RESPONSE OF FOAM ROLLING ON FLEXIBILITY

The following criteria were applied:

Population – any

Intervention – any self-myofascial release technique in >1 dose

Comparator – different doses of self-myofascial release

Outcome – any measurement of joint ROM acutely post-treatment

Results

The following 2 studies were identified (click to read): Sullivan (2013), Button (2014). These studies did not identify any dose response of self-myofascial release by altering either the time duration of the treatment or the number of sets.

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CONCLUSIONS REGARDING FOAM ROLLING

Self-myofascial release causes an increase in short-term flexibility that lasts for >10 minutes. It is currently not possible to identify any dose-response effect.

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ACUTE EFFECTS OF FOAM ROLLING ON PERFORMANCE

PURPOSE

This section sets out a summary of the research into the acute effects on athletic performance measures of foam rolling and other, similar types of self-myofascial release.

BACKGROUND

Definitions

For the definitions of fascia, self-myofascial release, and foam rolling, see the background section.

Popular usage

Although stretching has historically been the most common method for bringing about short-term increases in flexibility, some coaches are now beginning to make use of foam rolling either as an additive measure or as a replacement. Increasing flexibility is often required immediately prior to either resistance training or sports practice sessions, in order to ensure that the required joint ranges of motion (ROM) can be achieved.

Static stretching has historically been the most popular training method for increasing joint ROM, both in the short-term (i.e. acutely) and in the long-term (i.e chronically). Indeed, research has supported the use of static stretching for increasing joint ROM (see reviews by Decoster et al. 2005; Radford et al. 2006). Unfortunately, static stretching also appears to produce undesirable short-term reductions in athletic performance, although such reductions may be only pronounced when stretches are of long duration (>45 seconds) (see reviews by Behm and Chaouachi, 2011; Kay and Blazevich, 2012; Simic et al. 2013; Kallerud and Gleeson, 2013). However, if as appears to be the case, foam rolling can be used as a replacement training method to static stretching for increasing flexibility immediately prior to training without altering athletic performance, then it may be of use to strength coaches and sports coaches alike.

Literature usage

Foam rolling appears to be a suitable alternative to static stretching for bringing about short-term increases in joint ROM. Therefore, it is of great interest whether foam rolling also produces similar immediate reductions in athletic performance to static stretching. To explore this issue, researchers have assessed the extent to which foam rolling affects short-term performance in maximal and explosive force producing tasks, both relative to a baseline and also relative to a static stretching comparative group.

ACUTE EFFECTS OF FOAM ROLLING ON ATHLETIC PERFORMANCE

Selection criteria

The following criteria were applied:

Population – any

Intervention – any self-myofascial release technique

Comparator – baseline performance or a non-training control group

Outcome – at least one measure of athletic performance, including maximum force production (isometric or dynamic), explosive force production or power output, or anaerobic power output (e.g. a Wingate test), measured acutely post-treatment

Results

The following 6 studies were identified (click to read): Mikesky (2002), Sullivan (2013), Janot (2013), Halperin (2014), Healy (2014), Peacock (2014). None of these studies found any adverse effects on athletic performance as a result of self-myofascial release. One study found a benefit. This is in contrast to static stretching, which has often been found to display adverse acute effects.

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CONCLUSIONS REGARDING FOAM ROLLING

Self-myofascial release does not affect athletic performance in the short-term.

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ACUTE EFFECTS OF FOAM ROLLING ON DOMS

PURPOSE

This section sets out a summary of the research into the acute effects of foam rolling and other, similar types of self-myofascial release on delayed onset muscle soreness (DOMS).

BACKGROUND

Definitions

For the definitions of fascia, self-myofascial release, and foam rolling, see the background section.

Popular usage

Delayed onset muscle soreness (DOMS) is a problem incurred by many athletes and other individuals engaging in hard training. Most trainees prefer not to train or practice with DOMS and therefore attempt to make use of treatment modalities that claim to reduce such effects. Some clinicians, coaches and athletes believe that foam rolling and other self-myofascial release techniques can alleviate the sensation of DOMS, either before or after a workout.

Literature usage

Since athletes prefer not to train or practice with DOMS, researchers have attempted to identify any treatment modalities that are effective for reducing this problem. Unfortunately, most reviews have generally concluded that only really reliable method is exercise (Cheung et al. 2003) and that the outcomes of studies exploring other modalities tend to be extremely variable (Lewis et al. 2012).

Measuring pain

When measuring pain in the context of DOMS, there are two basic types of measurement that are commonly taken: perceived soreness (either at rest or during movement) and pain on palpation. Perceived soreness is commonly measured using either the Visual Analog Scale (VAS) or the BS-11 Numerical Rating Scale. at rest or during movement. A reduction in the VAS or BS-11 scale means a reduction in perceived soreness. Pain on palpation is most commonly measured by reference to Pressure Pain Threshold (PPT). An increase in the PPT means that the pressure required to bring about a pain response has increased. The type of measurement used (i.e. perceived soreness vs. pain on palpation) may affect the results observed, as Vaughan and McLaughlin (2014) reported that 3 minutes of self-myofascial release with a foam roller on the iliotibial band increased PPT acutely in healthy, asymptomatic individuals even in the absence of DOMS.

ACUTE EFFECTS OF FOAM ROLLING ON MUSCLE SORENESS

Selection criteria

The following criteria were applied:

Population – any

Intervention – any self-myofascial release technique

Comparator – baseline

Outcome – at least one measure of delayed onset muscle soreness (DOMS). Outcome measures included any measurement of pain, including Visual Analog Scale (VAS) or BS-11 Numerical Rating Scale at rest or during movement, or pain on palpation, by reference to Pressure Pain Threshold (PPT), measured acutely post-treatment

Results

The following 4 studies were identified (click to read): Howe (2013), MacDonald (2014), Jay (2014), Pearcey (2015). Of the 4 studies, 3 reported that self-myofascial release reduces sensations of DOMS (measured in various ways).

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CONCLUSIONS REGARDING FOAM ROLLING

Self-myofascial release may reduce perceived soreness and increase pressure pain threshold as a result of DOMS during the 48 hours following damaging exercise.

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CHRONIC EFFECTS OF FOAM ROLLING ON FLEXIBILITY

PURPOSE

This section sets out a summary of the research into the chronic effects on flexibility of foam rolling and other, similar types of self-myofascial release.

BACKGROUND

Definitions

For the definitions of fascia, self-myofascial release, and foam rolling, see the background section.

Popular usage

Greater flexibility is sometimes desirable not only immediately (i.e. acutely) prior to a single bout of resistance training or sports practice but also progressively over a long-term period of time (i.e. chronically). This is most commonly seen in sports that require substantially greater flexibility than is seen in the general population, such as gymnastics, track and field, and diving. Static stretching has historically been the most popular training method for bringing about both short-term (i.e. acute) and long-term (chronic) increases in joint ROM. Indeed, research has supported the use of static stretching for increasing joint ROM (see reviews by Harvey et al. 2002; Decoster et al. 2005; Radford et al. 2006).

Literature usage

Foam rolling appears to be a suitable alternative to static stretching for increasing joint ROM in the short-term (i.e. acutely). However, whether foam rolling can similarly produce progressive increases in flexibility over a long-term (chronic) period of time is less clear. Because static stretching is the conventional method for increasing flexibility progressively over a long-term period, many studies assess the extent to which foam rolling can produce chronic increases in joint ROM relative to a baseline as well as relative to a static stretching comparative group.

CHRONIC EFFECTS OF FOAM ROLLING ON FLEXIBILITY

The following criteria were applied:

Population – any

Intervention – any self-myofascial release technique

Comparator – baseline

Outcome – at least one measure of flexibility (typically joint range of motion) measured chronically after >1 week

Results

The following 3 studies were identified (click to read): Miller (2006), Ebrahim (2013), Mohr (2014). Of these 3 studies, 2 reported that self-myofascial release leads to increased flexibility over chronic periods of time, although the quality of these studies is very low.

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CONCLUSIONS REGARDING FOAM ROLLING

Self-myofascial release may be able to increase flexibility in a long-term program of >2 weeks.

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OTHER EFFECTS OF FOAM ROLLING

PURPOSE

This section sets out a summary of the research into the other effects of foam rolling and other, similar types of self-myofascial release. Since self-myofascial release is seen by many as a recovery modality, recovery is the most commonly-seen topic in this section.

BACKGROUND

Definitions

For the definitions of fascia, self-myofascial release, and foam rolling, see the background section.

Popular usage

Although the most common specific reasons for using a foam roller are (1) increasing flexibility (either in the short-term just prior to a workout or over the long-term), and (2) reducing muscle soreness post-workout, foam rolling and other self-myofascial release techniques are frequently categorized together with other tools as “recovery” modalities. Whether this refers to the ability of self-myofascial release to reduce muscle soreness specifically or to enhance recovery from workouts more generally is unclear.

Literature usage

Definitions of recovery

Recovery is a simple enough concept but has proved very difficult to investigate. It can be defined as the rate at which the fatigue induced by a prior training bout or competition is dispersed, relative to the magnitude of that fatigue. However, fatigue is hard to measure directly and we currently have a poor understanding of what it entails. We can see that athletes display reduced performance across a range of measures after a hard workout or competition. We call this state of reduced performance a state of fatigue but we do not really understand why it happens and what it involves. Fatigue can be either of central origin (i.e. the central nervous system inhibits effort, perhaps as a safety mechanism to prevent excessive damage to the muscles) or of peripheral origin (i.e. the performance capability of muscles is compromised, either through chemical changes, or as a result of localized tissue damage, or in some other way). It is likely that, in most cases in which athletes are in need of recovery, the nature of the fatigue comprises elements that are both central and peripheral.

Types of recovery

Researchers refer to three types of recovery: (1) immediate recovery is the recovery that is allowed during performance, between muscular contractions. For example, a certain amount of recovery for the leg muscles occurs during the flight phase of running between ground contact phases; (2) short-term recovery occurs between sets of intervals or between multiple sets of resistance-training exercises, and (3) training or long-term recovery refers to the period of adaptation between sequential workouts or between competitions. It is training recovery that is relevant for the purposes of self-myofascial release.

Proxy measurements for recovery

Researchers have identified a number of proxies of training recovery that might usefully be measured, either following a competition or workout or after a treatment modality, such as foam rolling. Such measurements include direct measurements of performance (e.g. maximal strength, repetition strength, muscular power or anaerobic power output), glycogen resynthesis, electrolyte replacement and rehydration, muscle damage biomarkers (e.g. creatine kinase), self-perception of delayed onset muscle soreness (DOMS), and heart rate variability (HRV), which helps establish proxies for the state of sympathetic or parasympathetic dominance. Since these are proxy readings for the state of fatigue that an individual is currently experiencing, relative to the state of fatigue that they were in prior to the competition, workout or treatment modality, they may not directly reflect the extent to which recovery has occurred but currently they are the best method we have of taking relevant measurements.

OTHER EFFECTS OF FOAM ROLLING

Selection criteria

The following criteria were applied:

Population – any

Intervention – any self-myofascial release technique

Comparator – baseline or non-training control group

Outcome – any but excluding flexibility, athletic performance, and delayed onset muscle soreness (DOMS), which were covered in the above analyses

Results

The following 3 studies were identified (click to read): Okamoto (2013), Kim (2014), Chan (2015). Self-myofascial release was found to decrease brachial-ankle pulse wave velocity, increase plasma nitric oxide concentration, reduce cortisol levels, and increase high frequency heart rate variability (HRV) percentage and reduced low frequency HRV percentage. Together, these studies provide a preliminary indication that self-myofascial release may affect parasympathetic nervous system activity, although further research is required in order to understand the mechanisms involved and the extent to which such effects are in fact meaningful.

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CONCLUSIONS REGARDING FOAM ROLLING

Self-myofascial release may potentially: improve arterial stiffness, improve vascular endothelial function, reduce cortisol levels post-exercise, increase parasympathetic activity (high frequency HRV), and reduce sympathetic activity (low frequency HRV).

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MECHANISMS OF SELF-MYOFASCIAL RELEASE

PURPOSE

This section sets out a summary of the research into the mechanisms by which foam rolling and self-myofascial release might exert their various effects, particularly in respect of increased flexibility and reduced muscle soreness.

CONTENTS

Click on the links below to jump down to the relevant part of the mechanisms section:

Background to fascia

Mechanisms for increasing flexibility

Mechanisms for reducing DOMS


BACKGROUND

Introduction

From the above sections, it is apparent that self-myofascial release may have a range of effects. The most interesting effects for strength and conditioning professionals and physical therapists are the acute (immediate) and chronic (long-term) increases in flexibility, as defined by improvements in joint range of motion (ROM), as well as the potentially beneficial effect on delayed onset muscle soreness (DOMS) after a workout. As noted above, it is unclear whether fascia does play a key role in mediating the effects of the myofascial and self-myofascial release treatments but since most of the popular mechanisms that have been proposed depend upon an understanding of the anatomy and biomechanics of fascia, a background to these topics is provided below.

Anatomy

Anatomically, researchers have differentiated between several layers of fascia: a superficial fascia, a deep fascia and visceral fascia. The superficial fascia is a fibrous layer with a membranous appearance and abundant elastic fibers and occasional thin sub-layers of fat cells interspersed between layers of collagen fibers. The deep fascia seems to differ in its make-up depending on anatomical location. In the trunk region, it is formed by a single layer of undulating collagen fibers mixed with elastic fibers (see review by Findley et al. 2012).

Biomechanics

Introduction

Many investigations have revealed that fascia alters its mechanical properties in response to mechanical loading. However, it has proved very difficult to match the in vitro changes in fascial properties subsequent to mechanical loading protocols with those seen in vivo, which may suggest that non-mechanical mechanisms are also involved.

Force application

Self-myofascial release, including foam rolling, involves applying pressure to muscle and fascia. The pressure applied by these techniques is a form of mechanical loading. Several researchers have investigated the magnitude of the forces applied during a range of different manual therapy techniques. Most of the early studies involved spinal mobilisations, which are not necessarily directly comparable with myofascial release techniques or self-myofascial release. Lee et al. (1990) investigated lumbar spine mobilisations at a low Maitland grade of pressure and observed a typical force of 33.3N. Matyas and Bach (1985) performed a similar study and noted a higher value of 20.4kg or 200N. Threlkeld (1992) performed a pilot study in two physical therapists performing thoracic spinal mobilisations at two different Maitland grades of pressure. For the two therapists, they observed ranges of 117.6 – 205.8N and 91.1- 140.1N at the lower grade and ranges of 352.8 – 499.8N and 231.8 – 303.8N at the higher grade.

In more recent studies exploring myofascial and self-myofascial release techniques, the results have been in a similar range. Chaudry et al. (2008) explored the force applied during myofascial release of the nasal fascia and reported a peak value of ~100N. Chaudry et al. (2014) reported similar values. Similarly, the pressure used by Sullivan et al. (2013) when applying a roller massager in a standardized format was 13.0kg or 127.4N.

Deformation

Like any solid, fascia responds by deforming when subjected to mechanical loading. In order to assess the extent to which fascia deforms in response to different durations and magnitudes of load, Chaudry et al. (2008) built a three-dimensional mathematical model modelling the effects of mechanical loading on fascial deformation during myofascial release treatments lasting 20 seconds. They found that the extent to which fascia deformed subsequent to myofascial release was highly dependent on the thickness of the tissue. For thin tissues, such as nasal fascia, they observed that typical forces (of ~100N) could produce up to 9% compression and 6% shear. However, for thicker tissues such as the fascia lata and the plantar fascia, they calculated that supra-physiological forces of ~ 9,075N or 925kg would be necessary to produce even 1% compression and 1% shear of the tissues in question. They concluded that conventional myofascial release would therefore be unable to produce meaningful deformation of these tissues.

Strain hardening

Strain hardening has been observed in fascial tissues subsequent to repeated mechanical loading. Strain hardening occurs in any material that exhibits both elastic and plastic qualities and represents a shift from less elastic to more plastic tendencies, thereby becoming more permanently altered in shape and less likely to return to its original form. Har-Shai et al. (1996) and Har-Shai et al. (1997) performed a series of mechanical loading tests of fascial sections of the superficial musculoaponeurotic system (a composite layer comprising collagen and elastic fibers interspersed with fat cells) with a range of velocities and displacements. They found a tendency towards an increase in stiffness and a reduction in viscoelasticity after multiple repeated loading protocols (i.e. strain hardening). Other researchers have similarly noted the same phenomenon of strain hardening with repetitive mechanical loading over time (e.g. Saulis et al. 2002; Rubin et al. 1998). Some reviewers have suggested that such changes could be caused by alterations in tissue hydration (Schleip et al. 2012a).


MECHANISMS FOR INCREASING FLEXIBILITY

Introduction

Flexibility can be defined as the ability to move through a large joint range of motion (ROM). Several studies have found that self-myofascial release can improve joint ROM both in the short-term (i.e. acutely) and in the long-term (i.e. chronically). However, the exact mechanism by which self-myofascial release might affect either muscle and/or fascia in order to bring about these increases in joint ROM is still unknown and the topic is highly contentious.

Categories of mechanism

In his exhaustive review of the potential mechanisms of myofascial release, Schleip (2003) divided the types of potential mechanism into two categories: mechanical and neurophysiological. A similar categorization has been adopted here, with the addition of a further category, which is sensation (see review by Weppler and Magnusson, 2010). Broadly speaking, the mechanical models were the first to be proposed, with the neurophysiological models being suggested only more recently. In this way, the history of the proposed mechanisms of myofascial release follows a similar pattern to our understanding of the mechanisms of static stretching (see review by Weppler and Magnusson, 2010). Whether the history will continue in the same pattern and we will ultimately find ourselves identifying the mechanism of myofascial release as being a function of altered sensation, in the form of increased stretch tolerance, however, remains to be seen.

Mechanical mechanisms

Mechanical mechanisms of self-myofascial release

Introduction

In mechanical models, which were among the first explanations to be proposed, it is suggested that the stretch or pressure that are involved in self-myofascial release or myofascial release lead to changes in the structure or mechanical properties of the fascia or muscle tissues. Within this category, there are many different types of potential change that have been suggested. The essential common feature of the mechanical models is that myofascial release can induce alterations in the microscopic anatomical structure of fascia by means of stretch such that the fascia becomes more elastic and less fibrous, which thereby decreases tension in associated segments during joint movements (Barnes, 1997). However, there have been a great many different proposals regarding the precise nature of the microscopic anatomical changes and consequently the mechanisms by which they might occur.

Thixotropy

In their early reviews, both Barnes (1997) and Schleip (2003) only identified two mechanical models: thixotropy and piezoelectricity. Thixotropy is the time-dependent material property of changing from a viscous state to a fluid state in response to the application of heat or kinetic energy. Schleip (2003) observed two important problems with the idea that myofascial release was primarily effect via the mechanism of thixotropy. Firstly, he observed that much longer periods of time and/or much greater force are required than are customarily produced during myofascial release treatments in order to cause changes in the viscosity of connective tissues. Secondly, Schleip (2003) noted that the thixotropic effect only lasts briefly after their administration. Thus, the effects of myofascial release would dissipate quickly post-treatment, which is not always observed in practice.

Piezoelectricity

In their early reviews, both Barnes (1997) and  (2003) only identified two mechanical models: thixotropy and piezoelectricity. Piezoelectricity is the material property of producing an electric charge in response to mechanical loading. Indeed, researchers have found that fascia does indeed possess such piezoelectric properties (e.g. Rivard et al. 2011). Barnes (1997) initially understood that such a mechanism might be capable of being immediate, insofar as the change in electrical charge of the collagen and proteoglycans within the extracellular matrix could lead to a change in the state of the fascial tissue from being more viscous to being less viscous. However, other researchers envisaged the process as affecting fibroblasts and fibroclasts rather than fascia itself, which Schleip (2003) observed would be associated with a far longer time-course than is typically observed during myofascial release treatments.

Rehydration

Schleip et al. (2012a) reported that fascial properties are mechanically altered in animal models through changes in water content. Specifically, they noted that strain hardening occurred subsequent to isometric loading and was accompanied by a loss in fascial water content. Since approximately two-thirds of fascia is water by volume (see review by Schleip and Müller, 2013) and since the water content of fascia responds so readily to pressure, it is feasible that fascia may lack water in certain areas because the body has experienced inappropriate or undesirable loading patterns. This lack of water may lead to a reduction in flexibility. Since fascia can become dehydrated, it has been suggested that the application of external force may be required in order to redistribute water and rehydrate the tissues (see review by Schleip and Müller, 2013). This external force could be supplied via myofascial release techniques.

Pathological adhesions

Some researchers have suggested that adhesions may occur between fascial layers and might be encouraged to disperse by appropriate application of pressure (see reviews by Evans, 2002; Hedley, 2010; Tozzi, 2012; Martínez Rodríguez et al. 2013). This idea seems to be closely related to the concept of assisting the different layers of fascia to glide over one another more easily (as in the review by Tozzi, 2012). Hedley (2010) defined a pathological adhesion as “a fixed connection between tissues which would normally slide relative to each other.”

Some researchers have presented evidence in favor of the direct effects of manual therapy techniques on adhesions, albeit in the context of abdominal massage rather than myofascial release. Bove and Chappelle (2012) reported that manual therapy reduced the incidence of peritoneal adhesions post-surgery in a rodent model. In this context, adhesions were defined as “pathological bands of fibrous connective tissue [occurring] between abdominal or pelvic organs and other structures, including viscera and the abdominal wall” and were expected to arise during surgery.

The concept of adhesions has been incorrectly related to the idea of thixotropy. Some reviewers have proposed that the removal of adhesions forming cross-links between layers of collagen fibers could be similar to the change in material properties from a more viscous to a less viscous state (for example, see review by Martınez Rodrıguez et al. 2013). Since the removal of adhesions is a permanent and not a temporary change, this mechanism cannot be thixotropy, which is the transient change in the state of a material from a more viscous to a less viscous condition as a result of the application of heat or kinetic energy.

Martınez Rodrıguez et al. (2013) suggested that in the normal process of acquiring muscle damage through either strenuous exercise or strain injury, the process of myofascial repair leaves scars in the connective tissue and the accumulation of distorted, fibrotic elements, which may adversely affect contractile function and reduce joint extensibility. The development of adhesions between layers of fascia in this way might be removed through the application of myofascial release treatments. Martınez Rodrıguez et al. (2013) suggested that it might be possible to measure and quantify the presence and removal of these adhesions using real-time sonoelastography.

Sonoelastography is a type of ultrasound imaging scan in which Doppler techniques are used to record the behavior of low amplitude, low-frequency shear waves (<0.1mm amplitude and <1 kHz frequency) propagated through the body. The waveforms detect changes in the material properties of the body tissues by decreasing the amplitude of the waveform when they meet harder or less elastic areas of tissue within surrounding softer or more elastic tissues (see review by Taylor et al. 2000). It is possible to assign grades or colours to areas of tissue that reach certain elastic property thresholds, thereby allowing a quantitative analysis of tissues both pre- and post-treatments. It is encouraging that previous attempts to investigate the elasticity of fascia using standard ultrasound have indeed observed changes in collagen density (e.g. Pohl, 2012). However, the precise underlying mechanisms of any changes in fascial elasticity may not necessarily be elucidated by such methods.

Fascial inflammation

Some researchers have proposed that muscle and/or fascia may under some circumstances tighten as a result of inflammation in the fascia (see review by Findley et al. 2012). It has been suggested that the way in which myofascial release and self-myofascial release therapies might reduce inflammation in fascia is by increasing blood flow.

There are some indications that myofascial release techniques may be able to increase blood flow. For example, Walton (2008) observed that myofascial release was effective in alleviating symptoms of Reynaud’s syndrome, which is a condition characterised by increased sympathetic nervous system activity leading to vasoconstriction and reduced blood flow. However, the mechanism by which myofascial release or self-myofascial release might improve blood flow is uncertain and may be multifactorial.

There are indications that direct pressure by myofascial release or self-myofascial release may produce both a direct effect on tension in the smooth muscle of the arteries and also an increase in vasodilators, thereby enhancing blood flow. Okamoto et al. (2014) observed an improvement in arterial stiffness and an improvement in vascular endothelial function as a result of a self-myofascial release intervention using a foam roller. Regarding the improvement in arterial stiffness, they suggested that this might have occurred because of a decrease in smooth muscle tension subsequent to the application of pressure with the foam roller. Regarding the improvement in vascular endothelial function, they suggested that the pressure may have triggered the release of plasma nitric oxide concentrations, by means of the pressure elevating flow velocity in the veins and increasing shear stress on the walls of the vasculature, which is a well-known stimulus for producing nitric oxide, a vasodilator. In this context, it is interesting to note that Queré et al. (2009) found improvements in arterial stiffness in normotensive and hypertensive patients after massage therapy and they also ascribed these effects to the actions of plasma nitric oxide.

There are indications that direct pressure by myofascial release or self-myofascial release may modulate sympathetic and parasympathetic nervous system activity, which could thereby have an effect on vasodilation and thereby enhance blood flow. Chan et al. (2015) noted an increase in parasympathetic activity and a reduction in sympathetic activity after a similar protocol. Similar increases in parasympathetic activity have been observed subsequent to massage therapy, which might be connected to reductions in heart rate and blood pressure, as well as increased endorphin levels (see review by Weerapong and Kolt, 2005).

Myofascial trigger points

Myofascial trigger points are “tender spots in discrete, taut bands of hardened muscle that produce local and referred pain” (see review by Bron and Dommerholt, 2012) that may be related in some way to a range of musculoskeletal disorders. For example, Roach et al. (2012) found individuals with patellofemoral pain syndrome had a higher prevalence of myofascial trigger points in the gluteus medius and quadratus lumborum muscles on both sides. However, whether the the location of gluteus medius and quadratus lumborum trigger points are reliable intra- and inter-rater is currently in doubt (see review by Myburgh et al. 2008) and whether myofascial trigger points are indeed a specific phenomenon is therefore uncertain.

Nevertheless, it has been suggested that myofascial trigger points are caused when motor endplates release excessive acetylcholine, leading to localized sarcomere shortening and consequently very short muscle fibers in one particular area (see review by Hong et al. 1998). Indeed, in such myofascial trigger points, researchers have observed a disruption of the cell membrane, damage to the sarcoplasmic reticulum and a subsequent release of high amounts of calcium ions, and the presence of cytokines, indicating localized inflammation (see reviews by Gerwin, 2010; Bron and Dommerholt, 2012).

Consequently, some researchers believe that myofascial trigger points develop after muscle overuse, possibly following excessive eccentric muscular contractions, or sustained concentric muscular contractions to muscular failure, particularly where such contractions involve localized ischemia, which leads to a lowered pH and the release of inflammatory mediators (see review by Bron and Dommerholt, 2012).

Neurophysiological mechanisms

Neurophysiological mechanisms of self-myofascial release
Introduction

In neurophysiological models, which are now becoming more widely accepted than the older, mechanical models, myofascial release is thought to stimulate intra-fascial mechanoreceptors, which cause alterations in the afferent input to the central nervous system, leading to a reduction in the activation of specific groups of motor units. In this way, myofascial release does not affect the physical properties of the muscle or fascia but rather sends signals to the brain through afferent nerves, which then signals to the muscle to relax its excessively contracted state. As noted above, this model assumes that muscle tissue is responsible for the tightness and that it is muscle tissue that is being changed by treatment.

Golgi tendon organs (GTOs)

Several researchers and reviewers investigating the effects of both myofascial release and self-myofascial release have suggested that the increases in joint ROM might be caused by the effects of pressure on the GTO (Miller et al. 2006; Tozzi, 2012; Roylance et al. 2013). However, it is believed that stretching of the active muscle-tendon unit is the primary stimulus for the GTO and simply stretching a passive muscle-tendon unit does not have the same effect (see reviews by Moore, 1984; Jami, 1992; Schleip, 2003). Moreover, the diminished response of the GTO following passive stretch has been observed both in animal models (e.g. Stephens et al. 1975) and in humans in vivo following static stretching interventions (e.g. Miller and Burne, 2014). As Schleip (2003) notes, the reason for this lack of GTO response following passive lengthening may be because of the placement of the GTOs in series with muscle fibers. Thus, the elongation of the muscle-tendon unit during passive lengthening occurs predominantly in the muscle itself, while during active lengthening, the tendon is stretched to a far greater extent.

Ruffini and Pacini corpuscles

Golgi tendon organs (GTOs) are not the only receptors capable of detecting mechanical loading in myofascial tissues. Histological examinations have revealed that fascia contains mechanoreceptors known as Ruffini and Pacini corpuscles. For example, Stecco et al. (2007) explored the fascia covering the pectoralis major, the arm and the hand and observed extensive innervation of the fascia comprised of free nerve endings as well as a high density of mechanoreceptors, including Ruffini and Pacini corpuscles. In addition, Stecco et al. (2010) reporting finding Ruffini, Pacini and also Golgi-Mazzoni corpuscles in the ankle retinacula, while Stecco et al. (2013) similarly observed Pacini and Ruffini corpuscles in the plantar fascia, particularly in the medial and lateral portions.

While it is unclear how the presence of these mechanoreceptors relates to changes in myofascial elasticity, Schleip (2003) has suggested the possibility that where an increase in flexibility occurs following a treatment, this may be because pressure has stimulated some of these mechanoreceptors, which then signals to the central nervous system to alter levels of muscle activity in the muscle beneath.

In discussions of this potential mechanism, it is interesting to note that Button et al. (2014) reported a reduction in muscle activity as measured by electromyography (EMG) during a lunge exercise following an acute bout of self-myofascial release with a foam roller. This may provide some support for the presence of altered EMG activity as a result of self-myofascial release. In contrast, most previous studies exploring the effects of self-myofascial release on EMG activity have used maximum isometric voluntary contraction (MVIC) tests and have not noted any changes (e.g. Sullivan et al. 2013; MacDonald et al. 2013; Halperin et al. 2014).

Sensation

Introduction

In their review of the mechanisms of static stretching, Weppler and Magnusson (2010) explain that the main factor explaining the changes in flexibility following either acute or chronic bouts of static stretching is an alteration in stretch tolerance. This is because most measurements assessing changes in flexibility have used outcome measures that involve the subjective perception of sensation of stretch-related variables. For example, the reviewers note that the most common outcome measures are joint ranges of motion, to the point of resistance, stretch, discomfort, tightness, stiffness, and pain (Weppler and Magnusson, 2010). These measures are certainly subjective from the point of view of the subject and are not objective, as would be the case if joint range of motion in response to a fixed joint torque would be.

Stretch tolerance

Manual therapies, including those in which pressure is applied to the musculature (as in myofascial release and self-myofascial release), have been identified as having a number of different central and peripheral neurophysiological effects. In particular, a number of potentially pain-relieving (analgesic) effects have been observed, many of which are described in detail in the subsequent section (see mechanisms for reducing DOMS and also review by Bialosky et al. 2009). These pain-relieving effects could lead to an increase in stretch tolerance immediately following the application of the therapy, which could account for the immediate changes in flexibility that are frequently observed.

The central nature of these pain-relieving effects could be used to account for the apparently strange results of Grieve et al. (2015), who observed an increase in sit-and-reach distance following the application of a self-myofascial release therapy to the sole of the foot. In contrast, the additive effect of static stretching and self-myofascial release observed by Mohr et al. (2014) suggests that there are some potential differences in the mechanisms by which static stretching and manual therapy are effective for improving flexibility acutely. However, given the array of different mechanisms through which manual therapy appears to exert pain-relieving effects, it does not seem unreasonable to propose that this additive effect may simply be a function of differences in the precise mechanisms in which increases in stretch tolerance are achieved by each modality.


MECHANISMS FOR REDUCING DOMS

Mechanisms of reducing DOMS

Introduction

Delayed onset muscle soreness (DOMS) is pain in the muscles after a bout of exercise that may or may not be connected to actual underlying muscle damage, often where such exercise involved eccentric muscle actions or unaccustomed movements. DOMS commonly peaks 24 – 48 hours post-exercise. Since athletes prefer not to train or practice with DOMS, researchers have attempted to identify treatment modalities that are effective for reducing this problem. Reviews have generally concluded that only effective method is exercise (Cheung et al. 2003) and that the outcomes of studies exploring other modalities tend to be extremely variable (Lewis et al. 2012). Nevertheless, a small number of studies have found that self-myofascial release can reduce the sensation of DOMS in the short time following exercise. The exact mechanisms by which this occurs are unclear.

Self-massage and pain

Several studies have assessed the effects of self-massage (with the hands) on various measures of pain in a range of musculoskeletal conditions, including knee osteoarthritis (Atkins and Eichler, 2013), hand arthritis (Field et al. 2007), carpal tunnel syndrome (Field et al. 2004), and general hand pain (Field et al. 2011). It should be noted that the body of literature in this area is small, the outcome measure was musculoskeletal pain and not DOMS, the treatment protocols involved the hands instead of tools, and some of the trials also included practitioner-led manual therapy, which is a confounding factor. Consequently, the extent to which these findings can be generalized to the effect of self-myofascial release on DOMS is very unclear. Nevertheless, it may be relevant that reductions in measures of anxiety and depression were noted in some of these trials (Field et al. 2004; Field et al. 2007) as well as in other trials of the effects of self-massage on other variables, such as smoking cravings (Hernandez-Reif et al. 1999). Since changes in oxytocin have also been associated with shifts in anxiety and depression (see review by Cochran et al. 2013), it is possible that these effects are mediated by this or other endocrine hormones (see further in the following section).

Measurements of DOMS

When studying the effects of self-myofascial release upon DOMS, it is likely to be important to distinguish between the different types of pain measurement taken. The most common ones are the Pressure Pain Threshold (PPT), the Visual Analog Scale (VAS), and the BS-11 Numerical Rating Scale (BS-11) for pain. Broadly speaking, PPT measures the sensation of pain when touched (i.e. pain on palpation), while VAS and BS-11 tests measure the sensation of pain either at rest or during a specific movement (i.e. perceived soreness).

More specifically, an increasing level of PPT means that the threshold of pressure at which pain occurs has increased, as PPT is simply the minimum force at which the individual experiences pain. Tests of PPT have been found to be reliable both inter-rater and intra-rater (Jones et al. 2007). However, it may be important when measuring PPT to ensure that the testing location on the muscle is controlled carefully, as there are indications that changes in PPT differ between muscle bellies and musculotendinous tissue when tested in the context of DOMS, with muscle bellies being more sensitive to pain than musculotendinous sites (Nie et al. 2005).

Effect of self-myofascial release on DOMS

Endocrine hormone releases

Some researchers have suggested that the apparent increase in PPT following self-myofascial release may occur through the activation of pain-relieving release of the endocrine hormone oxytocin into the blood. Jay et al. (2014) found that self-myofascial release was able to increase the PPT in individuals who had experienced a workout designed to induce DOMS. In the discussion of their results, they observed that some (e.g. Frey Law et al. 2008; Buttagat et al. 2012; Andersen et al. 2013; Chatchawan et al. 2014) albeit not all (e.g. Toro-Velasco et al. 2009) studies of both hard (deep tissue) and light (superficial touch) massage have found increases in PPT post-treatment. Jay et al. (2014) noted that pain relieving responses have been observed in animal models following touch, which appear to be mediated by an endogenous release of oxytocin into the blood (Agren et al. 1995), while the direct administration of oxytocin appears to have an analgesic effect on musculoskeletal pain in humans (Yang et al. 1994). They therefore suggested that the sensation of touch may mediate a reduction in PPT through the production of an endogenous, anti‐nociceptive release of oxytocin.

Inhibition of pain feedback

It has been suggested that both measures of perceived soreness (VAS and BS-11) and pain on palpation (PPT) may be altered secondary to the activation of mechanoreceptors within muscle fibers, which then lead to the stimulation of large, primary afferent nerve fibers. Signals along these fast-conducting nerve fibers could then interfere with pain signals transmitted along slow-conducting, tertiary fibers and thereby produce inhibition of pain feedback in the spinal cord. Some researchers have proposed this mechanism as a way in which massage might exert its effects (see review by Goats, 1994; discussion by Andersen et al. 2014), building on the pain gate control theory (Melzack, 1982). This mechanism has the benefit of being able to explain the way in which all exercise, massage, and self-myofascial release treatments might be effective (as noted by Andersen et al. 2014).

Reduced inflammatory signalling

Some researchers have suggested that the changes in both perceived soreness and pain on palpation following self-myofascial release or other massage techniques may occur through its actions on inflammatory signalling molecules and/or pain mediators such as bradykinins (MacDonald et al. 2013; Andersen et al. 2014). Muscle damage often involves an inflammatory response in which molecules, including bradykinins, are released from muscle tissues. Many of these molecules can be detected by nociceptive receptors in the muscle, which then leads to sensitization of the affected area (Shah et al. 2008) and consequently a sensation of localized tenderness that can be measured using PPT. It has therefore been suggested that self-myofascial release and other massage techniques could squeeze out the inflammatory molecules, including bradykinins, from the muscle tissues and thereby reduce the extent of peripheral sensitization (Andersen et al. 2014). However, recent research in which muscle biopsies were taken pre- and post-myofascial release treatment to explore its effects on the levels of inflammatory myokines (interleukin-6 and tumor necrosis factor-α) have reported negative results (Vardiman et al. 2014).

Myofascial trigger points

Myofascial trigger points are “tender spots in discrete, taut bands of hardened muscle that produce local and referred pain” (see review by Bron and Dommerholt, 2012). Some researchers have argued that myofascial trigger points are implicated in the etiology of musculoskeletal pain (see reviews by Quintner et al. 2014). However, this idea has been strongly criticized (see reviews by Quintner et al. 2014). Furthermore, the extent to which the development of myofascial trigger points can be related to DOMS is unclear. However, some researchers have noted that there are parallels between the two phenomena, particularly in relation to the development of DOMS in response to eccentric muscle actions (see reviews by Gerwin et al. 2004; Dommerholt et al. 2006).

Few researchers have attempted to connect myofascial trigger points to DOMS. This is likely because myofascial trigger points are generally the provenance of researchers working to help resolve questions in the areas of musculoskeletal pain and physical therapy, while DOMS is generally more commonly addressed by researchers working in athletic development. It may also relate to the current controversy regarding the role of myofascial trigger points in myofascial pain syndrome (see review by Quintner et al. 2014).

Nevertheless, there have been a very small number of relevant trials performed in order to explore the relationship between myofascial trigger points and DOMS. Itoh et al. carried out a pilot study in humans in which they induced myofascial trigger points in the third finger of one hand by means of an unaccustomed bout of eccentric exercise to muscular failure, comprising 3 sets with 5 minutes of inter-set rest. Before and after this bout of exercise, they carried out a physical examination and measured pain on palpation. By physical examination, they observed that there was a raised area of tissue, which itself displayed a decreased pain threshold but which elicited referred pain to other areas on palpation. In a rodent study, Hayashi et al. (2011) also induced what appeared to be myofascial trigger points in a rat gastrocnemius muscle after a protocol intended to produce DOMS, comprising applied eccentric contractions over a period of 2 weeks. These findings suggest that there may be some relationship between the eccentric muscle actions, DOMS and myofascial trigger points but the precise nature of that association is currently unclear.

CONCLUSIONS REGARDING FOAM ROLLING MECHANISMS

The mechanism by which self-myofascial release affects flexibility is unclear. Current best evidence points towards a neurophysiological mechanism involving muscle activity for acute changes, which differs from the way in which stretching is effective.

The mechanism by which self-myofascial release affects DOMS is unclear. Current best evidence points towards the inhibition of pain feedback, which may be similar to the way in which exercise is effective.

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