Massage

Contents of Article

1. Summary
2. What is a massage?
3. Can massage improve recovery?
4. What are the physiological effects of massage?
5. What are the biomechanical effects of massage?
6. What are the neurological effects of massage?
7. What are the psychological effects of massage?
8. What are the immunological effects of massage?
9. Are there any issues with massage?
10. Is future research into massage needed?
11. Conclusions
12. References
13. About the Author

Summary

Massage after exercise (i.e. post-exercise massage) has been used for many years as a method to improve recovery in athletes, despite the presence of robust scientific evidence to support its effectiveness. Although there is a lot of published research on massage therapy, only a very small portion of it focuses on the use of massage in athletes.

Given the current evidence, post-exercise massage may be an effective tool to promote recovery, but not for the majority of reasons it is so often believed to be. Acknowledging the popularity of this recovery method, and the substantial lack of evidence, it is highly recommended that more research is conducted to fully understand its uses and limitations.

What is a massage?

Massage is defined as ‘‘mechanical manipulation of body tissues with rhythmical pressure and stroking for the purpose of promoting health and well-being’’ (1), and it is used in sports for many purposes (2, 3). These include:

• Pre-exercise preparation
• Post-exercise recovery
• Injury prevention
• Injury rehabilitation

This article will focus on the efficacy of post-exercise massage as a method of accelerating the recovery process in sports.

The practice of using post-exercise massage to facilitate recovery has been used for many years with scientific research dating back to the early 1970s (4). Over time, this recovery strategy has become a staple in many high-performance sports environments. It has been reported that 78 % of professional football (soccer) players use post-exercise massage as a means of recovery (5). Classical massage, otherwise known as Swedish or Western massage, appears to be the most common form of massage used within sporting settings, and certainly within athletic research (3). This form of massage includes techniques such as:

• Effleurage (sliding/gliding movements)
• Petrissage (tissue kneading or pressing)
• Tapotement (rapid striking)
• Friction (pressure application)
• Vibration (tremulous shaking movements)

Other techniques such as underwater water-jet massage (6), acupressure and connective tissue massage (7) are also somewhat common, however, these will not be discussed within the scope of this article.

Can massage improve recovery?

It seems to be a common belief that massage can positively enhance recovery, and there are many reasons people believe this to be true. Some of the most common reasons massage is thought to enhance recovery are (8, 3):

• Relieving muscle tension
• Reducing muscle pain
• Reducing muscle spasms and swelling
• Increasing local blood flow
• Promoting the delivery of oxygen and nutrients
• Increasing flexibility and range of motion
• Enhancing clearance of substances such as blood lactate or creatine kinase

However, there is little evidence to support some of these claims. In fact, there are many additional reasons that post-exercise massage may be beneficial which are not listed above. This article will, therefore, discuss the current body of research, and attempt to identify the mechanisms responsible for the enhanced recovery.

Various mechanisms thought to be responsible for massage’s ability to facilitate recovery have been researched; which include:

• Physiological
• Biomechanical
• Neurological
• Psychological
• Immunological

With these in mind, this article will now dissect each mechanism in order to provide a degree of clarity to this form of recovery. Figure 1 displays a theoretical model of the mechanisms currently thought to be responsible for the enhancement of post-exercise recovery.

What are the physiological effects of massage?

Increased Skin and Muscle Temperature

The repeated and continual rubbing of the skin causes friction, resulting in increased skin temperature (9) and a proposed increase in blood flow, otherwise known as hyperaemia. There is supporting evidence that effleurage can increase skin and intramuscular temperature as deep as 2.5cm, but muscle temperatures deeper than 2.5cm were not affected (10). Another study also reported that effleurage resulted in an increase in skin temperature, but this quickly returned to baseline after just 10 minutes (9). This suggests that massage, particularly effleurage, may have very little effect on intramuscular temperatures.

Increased Blood Flow

Various studies have been conducted on the effects of massage on localised blood flow and shown positive effects (increased blood flow) (4, 11-14), however, these studies severely lack authority due to their poor quality – that being, small sample sizes (11, 14, 4) and no reported statistical analysis (11 -14, 4). Other, more robust, studies have found no increase in blood flow following a massage intervention (15, 16). However, they did not measure microcirculation in the muscle which may have been affected. Another study even showed that post-exercise impaired muscle blood flow (17). All this indicates that massage may have little effect on localised blood flow to the muscle, and has not been explored in enough detail.

Aside from its influences on blood flow, one recent study has shown that post-exercise massage may be capable of improving blood vessel function after exercise (18), but this yet again warrants the need for more research.

Blood Lactate Removal

Blood lactate is often used as a measure of fatigue and recovery (19-22). Numerous studies have investigated the effects of massage on blood lactate removal (19, 21-24), with only two reporting any sign of increased removal (20, 24). Contrary, another study found that massage actually impairs the removal of lactic acid from within the muscle after exercise (18). The little quantity of supporting evidence, therefore, questions the ability of massage to promote blood lactate removal.

Hormonal Response

Massage therapy has been shown to cause changes in hormonal levels (cortisol and serotonin) in dance students (25), patients with low back pain (26), depressed adolescent mothers (27), and HIV-positive patients (28). Following the massage intervention, the dancers reported a reduction in anxiety (nervousness) and improved mood (25). Despite some research showing reductions in cortisol levels after massage treatment, a 2011 meta-analysis concluded that massage has no effect on cortisol concentrations (29). Whilst the mechanisms responsible for some hormonal changes (i.e. serotonin) are still unclear, a decrease in pre-competition nervousness/anxiety may be beneficial for sports performance (30).

What are the biomechanical effects of massage?

Passive Stiffness

Massage is often referred to as “soft-tissue mobilisation”, though there is little evidence to support its ability to reduce soft-tissue stiffness (31, 32). Having said that, three reports have shown decreases in passive muscle stiffness immediately following a massage (32-34), but this increase in tissue mobilisation returned to baseline after 24 hours (32). On the other hand, two studies have reported that massage had no effect on passive stiffness (31, 35). As a result, there is a lack of evidence to determine whether massage is an effective tool for decreasing passive muscle stiffness.

Active Stiffness

To the author’s knowledge, no studies to date have examined the effects of massage on active stiffness.

Joint Range of Motion

Static flexibility is often defined as “the range of motion available to a joint or series of joints” (36). Multiple studies have shown that classical massage is capable of increasing the joint range of motion (25, 37-39). However, it is very important to note that these studies are not particularly robust, and thus further investigation is encouraged (30).

What are the neurological effects of massage?

Parasympathetic Activity

The evidence supporting massage and other forms of soft-tissue therapy (e.g. myofascial trigger point therapy) and their ability to influence parasympathetic modulation appears to be mounting (9, 40-53). In other words, massage has been shown to increase parasympathetic activity leading to a reduction in blood pressure (48, 54, 55), heart rate (48), and an increase in heart rate variability (46, 49, 50, 51, 53).

An increase in parasympathetic activity simply relates to a heightened state of relaxation, often referred to as a “rest and digest” state. Whilst there is a substantial body of evidence supporting the use of massage to increase parasympathetic modulation, most of this research has been conducted in nursing and therefore outside of the athletic environment.

Neuromuscular Excitability and the H-Reflex

Neuromuscular excitability is measured by assessing changes in the Hoffman reflex (H-reflex) amplitude (30). In fact, this is the same technique used to measure any potentiation effects when attempting to induce post-activation potentiation (56, 57). Massage has been shown to reduce neuromuscular excitability (i.e. the H-reflex), and it is thought to do so by stimulating the sensory receptors and reducing muscle tension (58-61). Having said that, the cutaneous mechanoreceptors were not responsible for the changes in H-reflex amplitude in the calf muscle (60).

As a result, the inhibitory effects of massage may originate from either the muscle or deep tissue mechanoreceptors (30). This is supported by one study which found a greater reduction in H-reflex response with an increasing depth of massage (62). Put simply, massage depth may be an important factor in reducing neuromuscular excitability.

If massage is capable of reducing neuromuscular excitability, then this might be a reason why massage appears to be a useful tool for reducing muscle tension and spasm (cramping) after exercise. However, this is still a matter of speculation and more research is required to understand the relationship between neuromuscular excitability and massage.

Effects on Pain

Massage is commonly used to treat perceptions of pain following exercise (63, 25, 26, 64-66), and there appears to be a substantial body of evidence which supports massage’s effectiveness in reducing pain in various populations. For example, massage has been shown to reduce the perception of pain in the following:

• Endurance athletes (67, 68)
• Patients with metastatic bone pain (when cancer cells spread into bone tissue) (69)
• Patients with recurrent headaches (70)
• Post-operative pain (71-81)
• Back and leg pain in pregnant women (82)
• Children and adolescents with chronic pain (83)
• Children with cancer and “growing pains” (84, 85)
• Myalgia (pain in a muscle or group of muscles) (86-88)
• Adult cancer patients (89, 90)
• Patients with Carpel Tunnel Syndrome (91)
• Patients with lower back pain (92-97)
• Patients with distal radial trauma and those receiving needle insertions (98, 99)

Though massage has been repeatedly shown to reduce the perception of pain in a variety of populations, there are numerous methodological issues with many of these studies due to the complexity of pain science. To provide a little more detail, pain is not a ‘sensation’, but instead, a ‘perception’ manifested and regulated by a complex neuromatrix. However, the concept of pain is beyond the scope of this article.

Physiological (biochemical substances)

Neurotransmitter substances such as serotonin have been shown to reduce the symptoms of pain (100, 101). Massage has been shown to not only increase the levels of serotonin (102, 25) but also increase dopamine levels – a stress-relieving hormone (102). Thus, massage may be an effective tool for relieving pain by increasing both serotonin and dopamine – but to accept this as concrete evidence would be a matter of assumption.

There is a significant amount of research that repeatedly supports the effectiveness of massage for reducing the perception of pain, though the effects appear to be small (30, 63, 103-107), and the mechanisms are uncertain.

What are the psychological effects of massage?

Anxiety

Among a long list of others, various forms of massage have been shown to reduce anxiety in the following:

• Dancers (25)
• Patients with chronic pain (86)
• Children with illnesses (84, 108)
• Nurses (109, 110)
• Patients with lower back pain (111-113)
• Headaches (114-116)
• Healthy adults (117)
• Patients with generalised anxiety disorder (118)
• Stroke patients (119)
• Elderly (119, 120)
• Adults with hand pain (121)
• Patients with fibromyalgia (120)

Though many studies have shown that massage may be an effective tool for reducing anxiety, it is important to understand that these effects may only last for a short period of time (122). To the best of our knowledge, there is no substantial evidence to suggest that the effects of massage on anxiety are long-lived. Having said this, a reduction in pre-competition anxiety may have positive effects upon sporting performance.

Relaxation

The effects of massage on relaxation have often been measured using the Profile of Mood States questionnaire (POMS). Whilst the POMS questionnaire is a valid and reliable test, it is questionable as a method of measuring relaxation because it technically measures the following six sub-scales: tension, depression, anger, vigour, fatigue and confusion (123).

As a result, a more appropriate method of measuring both short- and long-term states of relaxation is needed. Despite this, recall previously that massage appears to be a potent tool for increasing parasympathetic activity, and this may provide a degree of support for massage to increase relaxation.

Perception of Recovery

Multiple studies have found that participants reported an increase in the perception of recovery after a massage when it was administered both during and after training (23, 124). Though an increased perception of recovery was reported, no physiological markers such as blood lactate and heart rate showed any sign of improvement.

Additionally, the perception of recovery was measured using the Perception Recovery scale which appears to be a useful and practical questionnaire, however, no research has attempted to correlate scores on the test with other markers of recovery (e.g. increased microcirculation, blood lactate removal and creatine kinase concentrations), so its validity is uncertain.

What are the immunological effects of massage?

Peripheral Neutrophil Levels

Post-exercise massage has been shown to modulate immune parameters (e.g. peripheral neutrophil levels) up to 24 hours after the massage (125). It is thought that this may be due to the relocating of the neutrophils from the treated area (126). In contrast, another study concluded that peripheral neutrophil concentrations may not be maintained two hours after the cessation of exercise and massage treatment (127). The little evidence on this topic means it would be senseless to assume that post-exercise massage can influence peripheral neutrophil concentrations.

Immunoglobulin A

Significant recovery of immunoglobulin A (IgA) has been reported after the administration of a post-exercise massage, with greater recovery in females than in males (128). In support of this, increases in IgA concentrations have also been reported post-massage in the elderly population (42).

Lymphocytes

Whilst two studies have observed small increases in certain lymphocyte concentrations (129-130), others have shown no change in other immunological cells whatsoever (B lymphocytes, T lymphocytes, NK cells, and monocytes) (131).

In conclusion, the function of the immune system is far more complex than simply measuring a few immune parameters, and given that there is so much disparity within the research, at this point, it is unclear whether massage can modulate immune parameters. This statement is supported by a 2015 systematic review on the immunological effects of massage after exercise (126).

Are there any issues with massage?

At present, there are a few main concerns regarding the justification and use of massage. Massage therapy is often promoted for reasons that may not be true. For example, many practitioners advertise its ability to promote healing, well-being, and recovery both physiologically and psychologically. The issue with such claims is the lack of scientific evidence to support them. It is especially important to soften our language with certain vulnerable populations (e.g. cancer patients or individuals with HIV) who may be looking for an “immune boost”, or a cure, from alternative and complementary medicines such as massage (132).

Is future research into massage needed?

Given the tremendous lack of research on athletic performance, the use of massage therapy in a sporting context could benefit from additional research in these areas:

• Effects of post-exercise massage on physiological markers (e.g. microcirculation, blood lactate concentrations).
• Effects of post-exercise massage on biomechanical markers (e.g. active and passive stiffness, joint range of motion)
• Effects of post-exercise massage on neurological markers (e.g. neuromuscular excitability, parasympathetic activity, pain)
• Effects of post-exercise massage on psychological markers (e.g. perceptions of recovery, relaxation, anxiety)
• Effects of post-exercise massage on immunological parameters (e.g. IgA, neutrophil and lymphocyte concentrations).
• Optimal massage duration for influencing recovery
• The optimal post-exercise interval before the onset of massage
• Comparison of techniques for influencing recovery

Conclusions

• There are many false accusations with regard to the application of massage which are not supported by scientific evidence.
• Massage may improve skin and muscle temperature, localised blood flow, and the release of serotonin, though these effects may be small and short-lived. On the other hand, massage may not affect blood lactate removal or reduce cortisol concentrations.
• Massage may reduce passive muscle stiffness and increase joint range of motion. Though there is no evidence regarding its effects on active muscle stiffness.
• Massage may increase parasympathetic modulation and decrease neuromuscular excitability.
• Massage may reduce the perceptions of pain by promoting serotonin and dopamine concentrations, but realistically its effects on pain are far from understood.
• Massage may reduce anxiety and increase the state of relaxation, potentially due to its influence on parasympathetic activity.
• Massage may have little, to no, effect on peripheral neutrophil concentrations. However, it may affect immunoglobulin A and lymphocyte concentrations, but the amount of evidence is scarce.
• Most research on massage is conducted within nursing, with very little performed in athletic populations.
• The current scarcity of research on the effects of post-exercise massage on recovery means regulations on accusations should be enforced/tightened until further knowledge is obtained.
• The effects of post-exercise massage on recovery are still substantially unknown.