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Why does massage make you feel good? Pleasure that is good for you Jessica Bale Therapeutic Massage Course 2004–5 Maitri Foundation, APNT With thanks for inspiration and dedicated teaching to Sheila and Martin and patience and humour from all my bodies Why does massage make you feel good? Contents Introduction ......................................................................................................................................... 4 The ‘non-measurables’...................................................................................................................... 4 Contact – attention – care – love ............................................................................................. 4 Expectation – placebo effect .................................................................................................... 5 Meditation – relaxation .............................................................................................................. 6 Healing and immunity ................................................................................................................ 6 Sensation of touch ............................................................................................................................ 6 Sensory neurons ........................................................................................................................... 7 Stimulation of sensory neurons ............................................................................................... 9 Passing signals between neurons .........................................................................................11 Sensory perception ....................................................................................................................12 The measurables .............................................................................................................................12 Effects of touch – why does massage make you feel good? ..............................................13 It feels nice ...................................................................................................................................13 Immediate tissue changes ......................................................................................................13 Autonomic nervous system (ANS) .........................................................................................14 Pain relief ......................................................................................................................................16 Reduction of stress reaction ....................................................................................................19 Stress response .......................................................................................................................19 Post-stress response ..............................................................................................................21 Chronic stress .........................................................................................................................21 Massage and the stress response .....................................................................................21 Different massage strokes – different effects? ........................................................................22 Conclusion ........................................................................................................................................27 Bibliography .....................................................................................................................................27 Notes ..................................................................................................................................................29 All images © Jessica Bale 2005 unless otherwise noted 2005 Jessica Bale 3 Why does massage make you feel good? Introduction Why does massage make you feel good? I had learnt about many of the effects of massage, such as the stimulation of the parasympathetic nervous system, but wanted to know more about how these effects come about and maybe even to address the question of why they happen. During the course of my research I have deepened my understanding of how the nervous system works, the interaction between the nervous, endocrine and immune systems, neurobiochemistry, how healing may come about, the importance of touch in human physical, mental and emotional development, relief of pain, reversal of the stress response and many other more or less related topics. I have also discovered the difficulty of carrying out research in this area, something I would like to be involved with at some time in the future. I have been fascinated by it all (well, most of it!) and envisaged this project growing ever wider and deeper. However, time being what it is I have had to focus on certain aspects only and save the broader issues for my continuing interest as I learn more as a massage therapist. I have chosen to study as my primary subject the way the nervous system carries information and the body’s use of chemical messengers in response to massage, relegating other topics (though of equal interest) to an introductory section. I am also focussing on the effects that you can actually feel at the time of or immediately following a massage, although I touch on some of the longer term effects in passing. This still leaves me a wide range of issues relating to the nervous, endocrine and immune systems to discuss. The ‘non-measurables’ The outcome of a treatment is frequently influenced by ‘nonmeasurable’ factors such as the mind–body–soul connection, subtle healing energies, and the interaction between the patient and therapist. Cassar 1999: 58 These factors also contribute to making massage feel good. If you feel uncomfortable with your therapist, it will be difficult for your body to relax and you will be fighting the physical and chemical processes towards relaxation the therapist is aiming to produce. Similarly having worries or concerns you cannot let go of may effect the outcome – massage can help you let go, but does not do it for you. Contact – attention – care – love The feeling that someone cares about you and is taking time to care for you (even if you are paying them) is a powerful factor towards feeling good about yourself. For many people with chronic illness this kind of regular contact may be essential in helping them over feelings of isolation or being nothing but a ‘body’ in the health system conveyor belt. Paying attention to parts of the body with pain, injury or illness can help someone focus consciously and unconsciously on that part to enable the body to focus its healing ability there. The body can also experience a different state than the painful/injured adapted state, and move towards that as ‘normal’. James Oschmann refers to intention in this context. Intentions are not trivial, because they give rise to specific patterns of electrical and magnetic activity in the nervous system of the therapist that can spread through their body and into the body of a patient. Oschmann 2000: 48 2005 Jessica Bale 4 Why does massage make you feel good? It is in this area that the positive flow of energy in the therapist can help the client’s body adapt to a more positive position and a greater feeling of well-being. This can be a whole mind-body feeling or can be in a specific area that was causing pain or other problems. I find this subject very interesting but difficult to understand. My own experience is of a feeling of ‘love’ pouring out of me and enveloping my client in a protective bath where they are free to let go of some of the things that are preventing healing in mind and body, and to let them find a healthier position for themselves. Since the whole body is interconnected, work on one part of the body may affect and help another become more healthy. The living matrix is a continuous and dynamic ‘supramolecular’ webwork, extending into every nook and cranny of the body … In essence, when you touch a human body, you are touching a continuously interconnected system, composed of virtually all of the molecules in the body linked together in an intricate webwork. … Effects on one part of the system can, and do, spread to others. Oschmann 2000: 48 Ruth Werner talks about massage as being a ‘pleasure that is good for you’ (Werner 2003). There are many pleasures we indulge in that are not good for us and we often have trouble allowing ourselves pleasure at all. We can regard massage as treatment for a particular problem and thereby allow ourselves a wholesome pleasure too. So we can experience the positive feelings of doing something pleasurable without perhaps the guilt we may feel in other circumstances. Emotions and sensations work together as I will discuss later with reference to neuropeptides. Positive feelings that someone is caring for you can alter the chemical state of your body to be more active in healing and restoring its balance. … effective bodywork is an act of intimacy and deep sharing of sensibilities, a communication, a communion, and ultimately the basis for a new sense of community. It is in utter contrast to the grim social bonds described by Malthus, the ruthless competitiveness presumed by Darwin, and the self-serving Id and Ego of Freud. It is a personal exchange untainted by obligations and power struggles, and as such is an opportunity to see, and to feel, and to understand both ourselves and another in an entirely new way. Deane 2003: 406-7 Expectation – placebo effect Belief that massage can be helpful has a powerful influence on the recipient’s self-healing mechanisms. Cassar 1999: 58 The thought that something is ‘just what we need’ can be sufficient to be ‘just what we need’. This can apply to food or drink, going for a walk, a long talk or even a good cry. It is not infallible but being in tune with our bodies can give us an insight into what will help us feel better. The placebo effect is a response to a treatment intervention that is unexpected and not easily explained, although often it has been suggested by the practitioner. This effect is inherent in all medical treatment and may simply reflect the body’s ability to respond favourably if both the client and the practitioner believe a treatment or 2005 Jessica Bale 5 Why does massage make you feel good? procedure is going to work. While the response mechanism is unknown, it is not imaginary (NPF 2005). Meditation – relaxation Just lying in a quiet room, closing one's eyes, and trying to stop thinking of those things that are troubling will have some effect on the ANS. Certainly, a restful few minutes can make one feel a bit better than before. Many of the endocrine and ANS [autonomic nervous system] operations are not easily altered through conscious intent, but hypnosis, meditation and even massage-induced relaxation can often allow these unconscious systems to be modified by a person. Noonan 1999 Healing and immunity This subject belongs both here and in the measurable section but as it is difficult to feel during a massage I will only deal briefly with it. The body’s healing and immune systems are stimulated by the stress response to injury or disease to ensure that any tissue damage can be dealt with quickly. However, after about half an hour of stress the body’s resources are diverted away from healing towards immediate life-conserving activities (ie energy and oxygen use) (Sapolsky 2004: 154). So if continuous stress is a problem for someone their ability to heal themselves will be compromised. Massage reverses the stress response (see p21) and can therefore start the healing process. There appear to be many neuropeptides involved in healing and immunity that are affected in various ways by our response to injury, pain and disease. These are vital self-protection but may become out of balance. It has been shown that massage can help this balance (eg increase in natural killer cells in Field 2000: 201-5). This may not result in an effect that can be felt immediately, but can set our bodies on a path towards better health. Sensation of touch The sensation of touch in its many forms is the brain’s interpretation of the many messages it receives when a person is touched. A touch can be a feather light stroke or the shortest pin prick, a thump, or a stab penetrating the skin, but a healthy brain can distinguish between them, know where the contact is and react appropriately if necessary. The messages are sent from sensors throughout the body as electrical and chemical impulses along nerves to the spinal cord; some go on to the brain via nerves called interneurons. Since humans have more than a thousand billion nerve cells this system is amazingly complex. The sensors are neurons with special capabilities to detect variables such as pain, pressure and temperature. There are two main types: mechanoreceptors monitor the position of connective tissue responding to weak signals, gentle pressure and movement and the normal range of motion at the joints. They are inhibited by nociceptive input. They are found through nearly all connective tissue. Nociceptors monitor abnormal input in connective tissue which results in changes in the sympathetic nervous system and can cause dramatic changes in the body. They 2005 Jessica Bale 6 Why does massage make you feel good? are inhibited by mechanoreceptor stimulation. They are found through nearly all connective tissue (AMMA 2003b). These sensory neurons do not receive information from other neurons, but generate an electrical signal when triggered in their specialised endings, which is transmitted along the nerve axon to other nerves. If the stimulus is strong enough a charge is generated which is passed along the nerve cell and sent across a gap to fire the next nerve cell and so to the brain. Each neuron sends the signal to many different neurons which will pass it along if there is a sufficient number of incoming signals. The message is acted upon in the spinal cord (reflex action) and brain (perception and action), again if there are enough incoming signals. The central nervous system discards more than 99% of all incoming signals as irrelevant. The action initiated by the brain could be muscle contraction or relaxation, stimulation of the sympathetic or parasympathetic nervous system or release of neuropeptides, transmitters and hormones among others. All these actions are activated by sending signals through motor neurons as an electrochemical charge in much the same way as other nerves. Sensory neurons There are sensory neurons all over the body which respond to different kinds of stimuli from inside and outside the body. Massage can stimulate many of these such as those listed in the table below. Sometimes the more specific senses such as hearing and smell can also be stimulated by the setting of the massage (eg using essential oils or playing music) but I am not going to deal with these here. Table 1 Sensory neurons Type of sensor Location Stimuli Free nerve ending Densely throughout the skin, periosteum and joint surfaces in varying branching forms; deeper in the body but sparsely Light continuous touch; pressure; mechanical, thermal and chemical pain Wrapped around all hairs Movement of the hair Slow adapting so fires while stimulus present Hair follicle organ Image Fast adapting 2005 Jessica Bale 7 Why does massage make you feel good? Meissner’s corpuscle Fast adapting so fires again when stimulus ceases Ruffini’s end organ Slow adapting Pacinian corpuscle Fast adapting Merkel’s disc Slow adapting Krause’s corpuscle Throughout skin but abundant on lips, fingers, genitals etc, just below the surface of the epidermis; ligaments, tendons and periosteum Very light moving pressure; discriminative touch; lowfrequency vibration; movement and location of limbs Deep in the skin; joints; muscle; tendon Continuous pressure on deep tissues; movement and location of limbs Deep in the subcutaneous layer of the skin; joints; tendons; internal organs High-frequency vibration; pressure changes Lower epidermis of the skin Light pressure; discriminative touch Eyes, lips, tongue, genitals Touch; possibly cold 2005 Jessica Bale 8 Why does massage make you feel good? Golgi tendon organ Junction between muscle and tendon Stretch or contraction of tendon – muscle force Musclespindle organ Muscle Speed of muscle contraction (used to control rate of contraction) Stimulation of sensory neurons I am going to use a pacinian corpuscle as an example sensory neuron to show how a signal is generated. At rest a pacinian corpuscle (in common with other cells) has a difference in electrical potential of about 60 mV – the inside is negatively charged and the outside is positive. This is caused by the concentration differences in various ions between the inside and outside of the cell and means that if a channel is opened in the membrane, ions will flow from high concentration to low. These channels are twisted protein chains formed into tubes inserted in the membrane which can open and close in response to many different stimuli and are ion-specific. When a pacinian corpuscle is deformed by pressure on the skin, the membrane surrounding the inner nerve ending is stretched and the sodium ion channels are opened. Sodium ions (Na+) move from the positively charged outside of the neuron into the negatively charged inside down the sodium concentration gradient. This causes the internal electrical charge to change from negative to positive. This is a generator potential and the beginning of the electrical signal. It then triggers the adjacent sodium channels to open, changing the polarity in the next section of nerve and moves the electrical charge along. At the same time the sodium ions are pumped back ready for the next stimulus1. When the first node of Ranvier (the gap between Schwann cells) is reached an action potential is triggered. This works in a similar way to a generator potential. Action potentials use both sodium and potassium channels to send a strong, quick signal which does not reduce with distance. This signal carries on down the axon of the neuron to the end where it is converted into a chemical signal and carried to the next neuron. The charge jumps over the myelinated areas of the Schwann cells increasing the speed the charge moves. 2005 Jessica Bale 9 Why does massage make you feel good? There needs to be sufficient stimulus (in this case pressure) to reach the threshold for that neuron to trigger a reaction. Greater pressure will increase the number of generator potentials triggered. In the pacinian corpuscle the reaction is very rapid – the neuron adapts very quickly to the stimulus and stops sending signals. It is also triggered when the pressure is released – so sends the signal to the brain that the stimulus has stopped. Other sensory neurons adapt more slowly and carry on sending signals while the stimulus is in place. 2005 Jessica Bale 10 Why does massage make you feel good? Action potential – when the charge inside the neuron reaches the firing threshold an action potential is triggered When a number of sensors in an area are stimulated by a touch they may all be triggered and each send one or more signals. This information is distributed through branching axons to many other nerves which integrate the information coming from different nerves. If the signal is strong enough in any receptor nerve, an action potential will be generated in that nerve and again be distributed through branching axons to yet other nerves. In this way the signal is carried to the brain together with an indication of its strength by the frequency of the signals. Passing signals between neurons When the signal reaches the end of the axon it is converted into a chemical signal which generates another action potential in the next neuron. Again these are cumulative and there needs to be a certain strength of incoming signal for the action potential to be triggered in the next cell. The gap between neurons is a synapse and chemical messengers are used to communicate between cells across this gap. There are many effects of these messengers, such as control of ion channels (eg opening, shape, voltage sensitivity), how the neurons work and use energy and even changing the structure of the cytoplasm in the neuron. These messengers can act slowly or fast. This leads to varied and complex signalling to the brain, which interprets and responds. When the action potential reaches the axon terminal it stimulates the release of neurotransmitters stored in vesicles there. The vesicles move towards the membrane, fuse with it and open up to release the contents into the synaptic cleft opposite the receptors in the postsynaptic neuron. These small-molecule neurotransmitters attach to the receptors in the post-synaptic membrane causing them to open and allow a flow of ions through. This changes the polarity (as in the sensory neuron) and so triggers an electrical charge called a synaptic potential in the next neuron. The most common neurotransmitters are glutamate and acetylcholine (ACh) which increase the charge (excitatory) and glycine and γ-aminobutyric acid (GABA) which reduce the charge (inhibitory). There is also a system that releases mainly peptides from large vesicles in the side of the presynaptic terminal and these work more slowly and generally act indirectly via second messenger systems. The frequency of the action potentials cause varying amounts of neurotransmitter to be released which is reflected in the size of the synaptic potential produced. Depending on the transmitter released it can also raise or lower the polarity of the membrane making it more or less likely that the signal is passed on. Each neuron can have many other neurons sending it signals. Therefore it has to integrate the synaptic potentials into a coherent signal to pass on, often to many other neurons. It does this by adding together the incoming excitatory signals and subtracting the inhibitory 2005 Jessica Bale 11 Why does massage make you feel good? ones to produce a local potential sent to the initial segment at the base of the axon. Here, if the threshold for firing is reached, an action potential is propagated and sent along the axon. There is an excellent animation of neurotransmission at the Lundbeck Institute’s Brain Explorer website (Lundbeck Institute 2005b). Sensory perception The action potentials are carried by the afferent nerves which run through two pathways to the brain: the dorsal column system is the white matter of the spinal cord and transmits precise sensations at high speed; the spinothalamic system is the grey matter of the cord and transmits cruder sensations such as pain, heat and cold and pressure at a slower speed. There are also sensory pathways coming down from the brain which regulate the signals from the sensory receptors. This allows selection of sensory information to occur based on previous experience and other incoming sensations at the time. This is why pain is so relative and ‘felt’ so differently by different people. Response to sensory information also occurs unconsciously in the spinal cord and lower brain. It is only when the signals reach the cerebral cortex that it becomes conscious. But all parts of the nervous system act in a highly synchronised way responding to the multitude of information being fed to it and keeping the body alive, healthy and active by directing the muscles, glands and organs. The information that controls the body runs along nerves in the same way as the sensory information through two pathways: the direct corticospinal pathway forms a direct connection between the cortex and specific motor neurons in the spinal cord. It is very fast and controls fine, conscious movements. The second is the multineuronal pathway which is a series of neurons that interconnect through the lower brain and organise the reflex actions of the spinal cord. This controls the many movements that occur unconsciously and that are needed to carry out a conscious movement (eg walking) as well as control of organs and glands. Both pathways work closely together to enable our bodies to stay alive and be under our control. If bodywork is to be more significant than just so many pokes and rubs, if it is to effect lasting changes, then it must not merely address the tissues. It must use tactile sensations to reach the mind, the whole mind, from the surface of the skin to the spinal reflexes, to the subconscious responses of the lower brain, to the fields of awareness in the cortex. When this happens, touch is genuinely, profoundly therapeutic. Juhan 2003: 182 The measurables I have to say first of all that these issues are strictly speaking measurable, but in practice many are difficult to measure accurately. There are many reasons for this. The main one is the sheer size and complexity of the body and the incredible interconnectedness of its systems: 10 billion neurons each with up to 10,000 connections and 10 times that number of supporting glial cells; at least 60 neuropeptides affect the nervous system each with their own receptors, often many different kinds on each cell; the endocrine and immune systems as well as gene expression all affect how the nervous system works. In addition there are the effects of non-measurable factors such as an individual’s past experience and the physical and emotional interaction of between client and therapist. 2005 Jessica Bale 12 Why does massage make you feel good? In scientific research one of the aims is to distance the researcher from the subjects, to have an objective result. Even when studying drug response the expectations of the subjects, their personal circumstances and even the way they have been treated in the past can all affect the outcome despite all efforts to remove these effects. With massage therapy the effects are all brought about by human interaction and so if these are diminished by controls you risk losing the very effects to be studied. There are also many areas of interaction we are only beginning to be able to study, such as the interaction of energy fields between people, how emotional states may be transferred, and so on. I imagine these may become measurable as we develop our knowledge and experience, but for the moment they are outside the scope of this project. There have also been issues with the methodology of some of the earlier research in the field, which casts some doubt on the findings of that research. Tiffany Field outlines the problems in the introduction to her review of the work at the Touch Research Institutes (Field 2000): a lack of properly conducted clinical trials with poor controls, small sample sizes and multiple treatments given to subjects with varying levels of problems. Coupled with the variety of massage therapy techniques used, this has made it very difficult to compare different pieces of research and build a broad picture. The Touch Research Institutes have now conducted many experiments to show what effects massage therapy does have in relation to a range of pathologies. Effects of touch – why does massage make you feel good? It feels nice For many people being stroked feels nice – the brain interprets the sensation of most massage strokes as pleasant. Exceptions to this obviously include uncaring massage or a ‘no pain no gain’ attitude, as well as associations with previous unpleasant or abusive experiences connected to touch. The sensory neurons register the pressure, touch, stretch, movement, heat and vibration going on in the body and send these messages as electrochemical impulses to the brain which perceives pleasure. Immediate tissue changes The ‘ahhh’ feeling when a stiff, tight muscle is released is caused by a number of factors. Under- or overused muscles, old injuries and scar tissue, adhesions and calcification in muscle and connective tissue can be uncomfortable and painful. Massage over these areas stretches the muscle to pump fresh blood through, reduces congestion and disperses toxins through the lymph and venous circulation. It can break down areas of calcification mechanically and by heat and break apart areas where adhesion has occurred. When over contracted muscles relax, they feel less painful and much more alive, with an easier, wider range of movement. Massage has been shown to relax muscles by studying the level of motor neuron excitability. This research measured how easily the motor neurons in the spine sent reflex control messages to particular muscles. Light and deep pressure, muscle tapping, as well passive stretching of tendons and muscles stimulates a wide range of receptors in the skin, muscle, tendons and joints which resulted in a reduction in excitability. It also showed that work on arm muscles can relax the muscles in the same side leg (Cassar 2004). So if muscles contract less in extent and frequency they also send messages to the brain to relax generally as no other action is currently required. The brain then feeds back messages to reduce the 2005 Jessica Bale 13 Why does massage make you feel good? excitability of motor neurons when it registers relaxation in the body: this process is a positive feedback mechanism that deepens the relaxation of the muscles. Releasing muscle contraction also gives more space to the adjacent nerves and blood supply causing better transmission of nerve impulses and circulation. The nervous system is particularly susceptible and becomes ineffective when not adequately supplied with oxygen. This increases the system’s efficiency and amount of sensory information available which contributes to the ‘more alive’ feeling the body can have after massage. Asthma, coughs and other respiratory problems can cause tightness in the muscles in the area around the lungs and shoulder girdle. Breathing can become immediately easier if these muscles are more relaxed with a resulting increase in relaxation and in oxygen supply to the whole body. Connective tissue (ground substance, blood, fascia, bone and organ covering, tendons, ligaments, cartilage, bone) is thixotropic. When not used fully it gels too much and becomes stiffer: this makes it difficult to transport essential items such as oxygen and waste products and results in congestion. It becomes harder to use that part of the body so it feels stiff and sore and can also mean other parts of the body are over-used to compensate for this lack of movement. The pressure and stretching of massage warms the connective tissues through friction and increases their metabolic rate and therefore their fluidity. This normalises the tissues and makes the affected area feel better – more alive and active (Juhan 2003: 68-9). James Oschmann (Oschmann 2000: 168–73) also discusses the effects of pressure on the connective tissues of the body. The gel (solid) state of cells and connective tissue becomes more fluid under pressure and then returns to gel when the pressure is released. This happens very quickly but enables trapped particles such as toxins to be flushed out into the interstitial fluid and so out of the body via the lymphatic and venous systems. These waste products get trapped in areas that become ‘densified’ as a result of trauma or disuse – this can result in a hardened feeling in the tissues accompanied by a feeling of stiffness or pain. The abdominal area can cause pain and tension when the digestive system is not working properly. Abdominal massage can ease this by moving the contents of the gut, clearing the ileocaecal valve and relaxing abdominal muscles contracted from pain. It also stimulates the vagus nerve, which controls the digestive system, encouraging better action. The effects of the massage can often be felt immediately when peristalsis is improved. Longer term improvement involves peptide release to stimulate better digestion and a general improvement in the working of the gut. Autonomic nervous system (ANS) The ANS controls the unconscious functioning of the body although it is possible to bring some aspects of it under conscious control. There are two systems within this: parasympathetic and sympathetic. The sympathetic nervous system is a survival mechanism which enables immediate action in the face of danger and keeps our major organs functioning. The parasympathetic controls the energy production and conservation systems of the body and stimulates the digestive, immune and reproductive systems into normal action aiding rest and repair. Both these systems work together to maintain an alive, healthy, reactive balance in the body’s major organs and systems. If the ANS is out of balance caused by too many stressors we risk a range of illnesses leading in the extreme to death or a slide into inaction (and again death) if there are too few. Our current western-style society leads more often towards an over active 2005 Jessica Bale 14 Why does massage make you feel good? sympathetic system as we deal with a continuous barrage of stressors in day to day life. Massage can work to rebalance the system and has a particular effect in stimulating the parasympathetic system (see p21). Receiving non sexual, nurturing, non threatening touch is one of the most important ways humans and other mammals have to keep a healthy stress response. Werner 2003b Relaxation is a state of deep rest in which the metabolism of the body slows: less oxygen is needed, the heart and respiration rates drop, blood pressure drops, and brain waves slow to an alpha state. It is induced by massage when the parasympathetic nerves are stimulated by the brain interpreting incoming sensory information as non-threatening, by the muscles relaxing and the release of certain neurotransmitters. This also affects emotional state and behaviour, leading to feelings of calmness and contentedness replacing anger or depression. There are over 60 different neuropeptide transmitters (the most recent count I could find) that have been shown to affect neurons and how they work producing a system of great complexity. They may have an excitatory or inhibitory effect, or both, and there can be many influencing how one cell works; this is mainly effected by the variety of receptors available. They are made from a small number of different chemical precursors. Many are found in non-neuronal tissue (eg 95% of serotonin is found in the gut); some are traditionally known as hormones (eg vasopressin or anti-diuretic hormone) or hormone regulators (eg thyrotropin-releasing hormone); some interact with the immune system. The parasympathetic nervous system activates some (eg serotonin) and the sympathetic others (eg histamine). ‘Each neurotransmitter is made by a small number of neurons whose cell bodies are clustered in specific areas of the brain. For example, noradrenaline is synthesised mainly by neurons in the brainstem … the cell bodies of the dopamine neurons are clustered in a few brain regions, most importantly those deep within the midbrain, in the substantia nigra. However, the axons of these neurons extend throughout the brain and influence almost the entire organ.’ (Lundbeck Institute 2005) It has been shown that massage affects the levels of a number of these neurotransmitters (Field 2000) decreasing stress, anxiety and improving mood. Field also notes a balancing of frontal EEG activation after massage, indicating a shift away from depression. She hypothesises that these factors may be linked in the changes that massage is causing in the chemical and electrophysiological systems of the body. Particular neurotransmitters are known to cause certain effects but as they interact with each other and other substances such as hormones there are probably many more actions than those currently understood. I will look at some here – others will be discussed under pain and stress relief. Serotonin Serotonin secretion is increased by massage (Field 2000). It is found mainly in the gut where it plays an important role in digestion. It has been shown that it is secreted in response to vagal stimulation, increased pressure in the gut and when the peristaltic 2005 Jessica Bale 15 Why does massage make you feel good? reflex is initiated and that it is also involved in initiating that reflex2 (Gershon 2001). It is also involved in cardiovascular regulation. The release of serotonin in the gut in response to increased pressure from a large meal is responsible for that sleepy, afterdinner feeling. Only about 2% of serotonin is found in the brain, but it is involved in a wide range of brain functions. It is concerned with mood control, regulation of sleep (melatonin is made from it), pain perception, body temperature, blood pressure and hormonal activity. Serotonin generally produces feelings of well-being and comfort. However, the complexities of neurotransmitter interaction probably mean it is implicated in a wider range of effects than this. Dopamine There is some indication that massage increases dopamine levels in the brain (Field 2000). Dopamine controls the flow of information between the frontal lobes and other areas of the brain which could be connected with the balancing effect of massage on frontal lobe activity3 (Jones 1999). This increases happy affect and dopamine is mainly associated with activating feelings of pleasure and enjoyment. It also appears to increase desire and motivation. It has other effects and is critical to the way the brain controls our movements. Histamine Histamine is released in response to antigens in the body to produce many of the effects of inflammation and hypersensitivity and is generally considered an effect of the sympathetic nervous system. It relaxes the vascular smooth muscle to dilate the capillaries decreasing blood pressure, makes the capillaries more permeable which allows fluid to escape into the tissues creating oedema and inflammation, and contracts bronchial smooth muscle. These protect the body and allow the immune system to deal with the antigens. It also stimulates gastric secretion and acts as a neurotransmitter. It is thought that massage stimulates histamine relief which is responsible for lowered blood pressure. Pain relief Pain is a language. To the body it is a language of expression. To the therapist it is a language of science and physiology. … Pain may be related to tissue damage and pain stimuli, or it may not be. Pain is an unpleasant experience in the body that is ‘filtered’ through our mind and emotions, and as such is experienced differently and expressed differently from individual to individual. AMMA 2003a Pain is useful to the extent that it motivates us to modify our behaviors in order to reduce whatever insult is causing the pain, because invariably that insult is damaging our tissues. Pain is useless and debilitating, however, when it is telling us that there is something dreadfully wrong that we can do nothing about. Sapolsky 2004: 187 We need pain. It protects us from ourselves and the environment. But disease that has chronic pain as a symptom is debilitating on top of any other symptoms felt. Chronic muscle pain due to contracted or damaged muscles drains energy and distracts from enjoyment of life. 2005 Jessica Bale 16 Why does massage make you feel good? Pain can be immediate, acute or chronic. In the immediate phase following injury or trauma there may be little or no pain perception, it is in this stage that other behaviors such as the fight or flight response may take precedence as the body attempts to avoid further pain. In the acute phase the pain provokes coping mechanisms and preparation for recovery, which may include seeking assistance with the injury or trauma. The chronic phase of healing and recuperation is characterized by behavior related to recovery, rest and management of the injury for the goal of complete restoration of function. AMMA 2003a Pain comes in various forms according to its underlying cause but is felt in many different ways by different people. Table 2 Different types of pain Neuropathic Caused by damage or pain dysfunction of nervous system Damage caused by mechanical, chemical, heat/cold, disease eg herpes zoster Follows dermatomes ie area of skin innervated by single nerve root Localised, sharp pain or pins and needles or numbness Nociceptive pain Abnormal temperature, mechanical, chemical stimulation Follows sclerotome pattern ie along nerve path Deep, aching diffuse pain Caused by stimulation of nociceptor in myofascial tissue and joints Psychogenic Generated by mind and pain emotions Can affect perception of pain stimulation Visceral pain Mechanical eg ischemia, chemical irritation, acidity, spasm, over distension In visceral organs and their coverings Often referred to surface of body eg gallbladder to right shoulder, cardiac pain up neck to jaw Nociceptors are nerve endings that monitor abnormal input in connective tissue which is generally interpreted by the brain as pain. They are found all over the body and help the brain to deal with injury. Neurotransmitters such as bradykinin, histamine, prostaglandins and substance P are released at the injury site, increase the pain threshold and stimulate the nerve endings to send the pain signal to the brain which can then take action. 2005 Jessica Bale 17 Why does massage make you feel good? Opioid peptides Endogenous opioid compounds – enkephalins, dynorphins endorphins – are made and released in pain perception parts of brain. They reduce the firing threshold for neurons that carry pain messages to the brain to cause analgesia and sedation. The endogenous opioids are a large family of neuropeptides widely distributed throughout the central and peripheral nervous systems. These neurotransmitters are crucial to the normal functioning of important processes such as motor coordination, learning and memory, gastrointestinal function, the control of seizures, and the hormonal regulation of the reproductive system, yet they are most often recognized for their central role in the modulation of pain. MNE 1998 Massage reduces pain effectively and over a wide range of conditions (Field 2000). It works through a number of mechanisms some mechanical, some chemical. Physical changes mean the problem is no longer there eg an over contracted muscle which relaxes will stop firing the nociceptors and they will stop sending pain signals to the brain. Stimulation of mechanoreceptors (eg by pressure) can send messages which reduce the firing threshold of nociceptors so they fire less often and less pain is felt. Nociceptor inhibition can be accomplished through massage and manual therapy technique that stimulates the pain sedating mechanisms of the nervous system. AMMA 2003a The ‘pain gate’ mechanism4 means that a short, sharp pain can remove the sensation of a continuous, throbbing pain briefly by blocking the impulses in the spinal cord. The continuous flow of sensory information during massage can keep the ‘gates’ closed or only partially open, thus reducing pain impulses reaching the brain. Transmission of continuous pain (rather than sudden, sharp pain) signals is slower than that of other signals such as pressure because the nerve fibres are smaller and not myelinated. When a painful area is stimulated by touch this signal blocks the later, pain, signal from reaching the hypothalamus and cortex. … pleasurable touch reaches the brain before pain and can cancel the pain out. (Juhan 2003) The endogenous opioids are released by massage and reduce the pain messages at the nerve endings, in the spinal cord and brain. Massage often promotes deep, restorative sleep which stimulates the body to produce somatostatin, which modulates pain experience. In contrast, if deep sleep is missed substance P is released which increases the firing threshold of nociceptors and therefore the amount of pain felt (Field 2000: 86). Substance P and other pain enhancing chemicals are removed from the circulation by the increased venous blood flow resulting from massage (Cassar 2004). This will reduce stimulation of the nociceptors. All of these effects (except the first) change the brain’s perception of pain by reducing the number of signals reaching it, rather than reducing the causes. In some cases the effects of the massage will be reversed after a while and the increase in signals will 2005 Jessica Bale 18 Why does massage make you feel good? result in the increased perception of pain. Sometimes the reduction in pain will be sufficient for the body to relax enough to remove the cause of the pain (eg a contracted muscle) and the massage will be effective. This effect can build up over a number of sessions. Reduction of the stress response As a result of the relaxation provided by massage therapy, the recipient’s sensitivity to anxiety and stress is likely to be reduced. This in itself may be the only change needed for healing to take place. Cassar 2004: 58 Tactile stimulation (or the lack of it) produces certain emotional and conceptual responses in the higher brain; these feelings and concepts then exert an effect upon central nervous system activities as a whole and upon the production levels of the pituitary in particular. These pituitary secretions in turn affect the health of the connective tissues and their ability to respond to trauma. These effects are all very different from mere ‘relaxation,’ the result most commonly associated with bodywork. Juhan 2003: 85 Stress response The nervous system responds to perceived danger by putting the body into alert mode. This involves two systems of the body which work closely together: endocrine and autonomic nervous systems. The sympathetic nervous system is the part of the autonomic nervous system activated when we think we are in danger. The sympathetic nerves which run all over the body are stimulated to release norepinephrine at their endings. This causes changes throughout the body to prepare it for action (see Table 3 below). The sympathetic nerves also stimulate the adrenal glands to release epinephrine and small amounts of norepinephrine into the bloodstream which alerts the body for action (see Table 3 below). A number of releasing hormones are also secreted by the brain to help and sustain the stress response. Corticotropin releasing hormone (CRH) is released from the hypothalamus into a tiny network of capillaries connected to the pituitary gland. This is stimulated to release adrenocorticotropic hormone (ACTH or corticotropin) which is carried in the bloodstream to the adrenal glands. When sensed in the adrenal cortex glucocorticoid hormones are released into the blood, which also cause changes in the body to prepare for action. This is slower than the release of epinephrine and norepinephrine and so helps sustain the stress response. Some of the glucocorticoids aid recovery from the response and some prepare the body for the next attack in situations where there are repeated stressors. The pituitary secretes other hormones to stimulate organs throughout the body to release hormones to control many processes. It also secretes hormones that directly control processes (see Table 4 below). Hormones that control processes that are not important in the short term are inhibited by the stress response: reproductive hormones, growth hormones and insulin (glucose storage) along with the corresponding processes they control. 2005 Jessica Bale 19 Why does massage make you feel good? Body part Sympathetic nervous system effects Adrenal gland effects Results Skin Less blood flow Keep oxygen and nutrients in main part of body; less blood flow in case of injury Brain function Increase speed of working Increased alertness Muscles Increase blood flow More energy, oxygen and nutrients available to work harder Pupil dilation Better sight Less blood flow Increase sweating Contract arrector pili muscles and raise hairs on skin Eyes Increase sight Nose Increase sense of smell Lungs Relax bronchial muscles Bronchioles enlarge Increased respiration so more oxygen available Heart Increase heart rate Increase heart rate More blood can circulate to supply more oxygen and nutrients to muscles Blood supply Divert blood to skeletal muscle Increase blood pressure More blood to supply energy, oxygen and nutrients to muscles Liver Increase metabolic rate and release of glucose to raise blood sugar level Increase metabolic rate and release of glucose to raise blood sugar level More energy available Digestive system Decrease in digestion process Decrease in digestion process Divert resources for immediate survival Kidneys Water retention Water retention Divert resources for immediate survival Bladder Enlarges to contain more urine; sphincter tightens to stop emptying Adrenal glands Stimulate production of epinephrine and norepinephrine Sexual organs 2005 Jessica Bale Better smell power Divert resources for immediate survival Produce glucocorticoids Assist and sustain fight or flight reaction Reduce reproductive function Divert resources for immediate survival 20 Why does massage make you feel good? Table 3 (opposite) The body's reaction to stress through the sympathetic nervous system Table 4 Effects of some other stress hormones Trigger Organ CRH Adrenal (hypothalamus cortex to pituitary); ACTH (to adrenal glands) Hormone Effect Glucocorticoids Promotes breakdown of eg cortisol proteins to produce glucose Decreases white blood cells at injuries Reduces allergic reaction Result More energy for muscles Antiinflammatory agent Antiallergenic agent Pancreas Glucagon Raise levels of glucose in blood More energy available Pituitary gland ADH (antidiuretic hormone) Reduces water loss from kidneys Helpful in case of blood loss Pituitary gland Prolactin Suppresses reproductive system Diverts resources for immediate survival Post-stress response When the body perceives the danger is over the parasympathetic nervous system is activated and the sympathetic inhibited. This produces the opposite effects to the stress response and allows the body to recover and recuperate. So the processes that were stopped (eg digestion, growth, reproduction, energy storage, immune system) can start again. Chronic stress The stress response and recovery are normal and essential features of human life. It is the malfunction of the system that causes problems not the actual stress: in fact if we have too little stress our bodies cannot develop correctly (see Deane 2003: 313-16). But reactions to constant stressors or expectation of stress will lead to a continuous stress response, without the benefit of a restorative post-stress period. This in turn can contribute to many different kinds of illness and other health problems (eg depression, heart disease, emotional growth) as Robert Sapolsky demonstrates in his book Why Zebras Don’t Get Ulcers (Sapolsky 2004). Massage and the stress response Massage reduces release of stress hormones (eg cortisol) and catecholamines (epinephrine, norepinephrine) that prepare the body for fight or flight and stimulates the parasympathetic nervous system to bring the body towards a resting state (Field 2000: 219). One of the most important nerves for this is cranial nerve X – the vagus nerve. This controls heart rate, respiration, emotional response and the action 2005 Jessica Bale 21 Why does massage make you feel good? of the digestive system. When mechanoreceptors in the upper body are stimulated, they send messages to the medulla and pons which increase vagal activity by slowing heart rate, easing respiration and controlling the actions of the major organs to promote energy conservation and recuperation (Cassar 2004: 71). This means that massage is useful in situations where the body is stuck in a stress response or has a sluggish return to normal after stress. The results of regular massage to reduce the stress response can range from a renewed ability to relax and not become irritable or outraged at every little thing, through having a good nights sleep, reduction in symptoms of poor digestion, increase in sex drive and protection from repeated infections. Different massage strokes – different effects? I think it is clear that massage makes you feel good and can have long term health benefits. It can also make you feel unwell if used uncaringly or inappropriately or if your body has an unusual reaction to it. My experience has been that most people feel better generally and often in specific ways following a massage therapy session. In the table below I have discussed how the different strokes can be used to elicit different effects depending on the needs of the client. I have not discussed each technique in detail. 2005 Jessica Bale 22 Why does massage make you feel good? Table 5 Effects of massage strokes (based on Cassar 2004) Stroke Mechanical and reflex effects Effect on relaxation Effect on pain Other effects Effleurage Moves blood along blood vessels Nerve endings of sensory receptors of superficial tissues are stimulated so reflex pathways in the CNS react – muscles in the area relax the brain interprets touch as beneficial not threatening – muscles in this area relax Stimulates parasympathetic nervous system Stimulates release of neurotransmitters eg endorphins, histamine, serotonin Moves contents of hollow organs eg colon Certain regions have reflex effect eg enhances peristalsis in gut Relaxed muscles send messages to brain which stimulates the parasympathetic nervous system to relax body for rest and recuperation, reversing the stress response Serotonin produces calm and contented feelings Can induce alpha rhythm brain waves which are a meditative state Can induce deep sleep Reduced by increased venous flow removes inflammatory agents reducing nociceptor stimulation oedema reduced – built up fluids moved away mechanically and by increased circulation – reduces stimulation of nociceptors by pressure Blocks pain impulses travelling to spinal cord by pain gate mechanism Stimulates release of endogenous opioids (painkillers) Needs to be very slow and continuous for some minutes (within pain threshold) Reduces sensitivity and other tissue disturbances to improve function of related structures or organs Histamine dilates blood vessels to lower blood pressure Improves digestive action Improves breathing capacity Increases immune function Improves reproductive system function Improves vascular system function Stroking hands and arms over the body Light stroking 2005 Jessica Bale Venous return flow increased Toning effect on involuntary muscles of arterial walls 23 Why does massage make you feel good? Deep stroking Venous return and lymphatic drainage of deeper tissues increased Removal of lactic acid and other by-products of muscle activity relaxes muscle Stretch superficial fascia and reduce nodules and congestion Inhibitory effect on muscles and their sensory neurons (eg muscle spindles and Golgi tendon organs) motor impulses at neuromuscular endplates resulting in weaker contractions so muscles relax Petrissage Circulation increased in dermis and subcutaneous fascia Compresses deeper blood vessels against lower fascia which improves circulation here too (arterial and venous flow are affected) Muscular tissue and surrounding fascia is stretched which reverses shortening Lifting tissues off underlying structures with a twisting movement 2005 Jessica Bale Reduced by stretching muscle fibres increasing circulation releasing adhesions Fatigue reduced by increased circulation Improved vascular system function Imp[roved immune function 24 Why does massage make you feel good? releases adhesion between muscle bundles and layers Improved lymphatic drainage of muscle and superficial tissue – pump action Kneading Pressing tissues onto underlying structures using a kneading movement Friction Muscular tissue and surrounding fascia is stretched which reverses shortening releases adhesion Venous flow improved Causes vasodilation of superficial arterioles which improves local circulation Local circulation and temperature are increased in Working deeply deep and superficial tissues into muscles in by release of histamine like one place in small substance which dilates circles the capillaries the arterioles by an axon reflex mechanism Dispersion of calcifications around joints Releasing adhesions between tissue layers eg skin, fascia, muscle, tendon, aponeurosis, bursae, periosteum and ligaments 2005 Jessica Bale Muscles helped to relax more by heat releasing adhesions improvement in local circulation so they send messages to brain to relax body Reduced by removal of metabolites formed by repeated muscle contractions Needs to be very slow and continuous for some minutes (within pain threshold) Increased arterial circulation Reduces congestion, ischemia and fatigue by clearing by-products of muscle use Improves vascular system function Stimulation in the skin and fascia layers activates the pain gate mechanism – creating sufficient stimuli along quick fibres to block perception of pain Reduction in oedema reduces pressure on surrounding tissues Relaxed muscle is less painful Improved circulation Lowers blood pressure 25 Why does massage make you feel good? Heat is produced which helps stretch collagen fibres in fibrotic tissue Reduction of chronic oedema which tends to be more solid Percussion Cupped hand, side of hand and fisted hand movements rapidly and rhythmically over body Passive movements/ traction Increase local circulation Stimulate nerve endings – tiny muscular contractions increasing overall tone Nerve pathways are stimulated and restored Muscles, ligaments and Slowly and gently tendons are stretched moving or pulling Makes more space in joints a joint through its range of movement 2005 Jessica Bale Stimulates body Brain relaxes control of muscles Blocks pain messages by the pain gate mechanism creating sufficient stimuli along quick fibres to block perception of pain Can increase circulation in joints aiding healing and action Range of movement improved 26 Why does massage make you feel good? Conclusion The enormous complexity of the human body is just being discovered, yet we have been healing each other through touch since before humans evolved. I think that the current research into neurobiochemistry will explain a great deal about how this works and that investigation into the interaction of low energy fields between living beings will add another dimension to an already complicated subject. This important understanding of how massage works is fascinating and will build up the professional standing and practice of massage. But massage therapists will continue to learn from each other, their own experience and that of their clients to increase their practical understanding of what massage does and how to use it for the greatest benefit of their clients. Bibliography AMMA 2003a, American Medical Massage Association, Basic Concepts in Pain Physiology: For the medical massage and medical manual therapist, American Medical Massage Association, http://www.americanmedicalmassage.com/education/a36z4.html AMMA 2003b, American Medical Massage Association, A Comparison of the Somatosensory Effects of Therapeutic Massage and Medical Massage, American Medical Massage Association, http://www.americanmedicalmassage.com/education/a31z4.html Cassar 2004, Mario-Paul Cassar, Handbook of Clinical Massage: A complete guide for students and practitioners, Churchill Livingstone, 044307349X CNS Forum 2003, CNS Forum, The Na+/K+ ATPase, Lundbeck Institute, http:// www.cnsforum.com/imagebank/section/Other_Neurotransmission_Basics/default.aspx Field 2000, Tiffany Field, Touch Therapy, Churchill Livingstone, 0443057915 Gershon 2001, Michael D Gershon, The Enteric Nervous System: A second brain, Hospital Practice, http://www.hosppract.com/issues/1999/07/gershon.htm Hall 1992, Zach W. Hall (Ed), An Introduction to Molecular Neurobiology, Sinauer Associates Inc, 0878933077 Jones 1999, Nancy Aaron Jones and Tiffany Field, Massage and Music Therapies Attenuate Frontal EEG Asymmetry in Depressed Adolescents, Adolescence, Fall 1999, http://www.findarticles.com/p/articles/mi_m2248/is_135_34/ai_60302519 Juhan 2003, Deane Juhan, Job’s Body: A handbook for bodywork, Barrytown/Station Hill Press, Inc, NY, 1581770995 King 2005, Michael W. King, Common Vertebrate Hormones, Indiana University School of Medicine, http://web.indstate.edu/thcme/mwking/hormone-table.html Lundbeck Institute 2005a, Lundbeck Institute, Neurological Control, Lundbeck Institute, http://www.brainexplorer.org/neurological_control/Neurological_index.shtml Lundbeck Institute 2005b, Lundbeck Institute, Neurological Control, Lundbeck Institute, http://www.brainexplorer.org/neurological_control/Neurological_Neurotransmission. shtml# 2005 Jessica Bale Why does massage make you feel good? MNE 1998, Multimedia Neuroscience Education, Synaptic Transmission: A four step process, Williams College Neuroscience, http://www.williams.edu/imput/synapse/pages/ IB1.html Noonan 1999, Tim Noonan, The Effects of Massage on the Autonomic Nervous System, Tim Noonan, http://www.softspeak.com.au/maspap98.htm NPF 2005, National Pain Foundation, CRPS - Definitions, National Pain Foundation, CO, http://www.nationalpainfoundation.org/MyTreatment/articles/CRPS_PainDefinitions.asp Ornstein 1990, Robert Ornstein and Charles Swencionis (Eds), The Healing Brain: A scientific reader, The Guilford Press, 0898624630 Oschmann 2000, James L Oschmann, Energy Medicine: The scientific basis, Churchill Livingstone, 0443062617 Paulev 2000, Poul-Erik Paulev, Textbook in Medical Physiology and Pathophysiology: Essentials and clinical problems, Copenhagen Medical Publishers, http://www.mfi.ku.dk/ppaulev/content.htm Sapolsky 2004, Robert M. Sapolsky, Why Zebras Don’t Get Ulcers: The acclaimed guide to stress, stress-related diseases, and coping, Henry Holt & Co, 0805073698 Selye 1978, Hans Selye, The Stress of Life (revised edition), McGraw Hill Inc, 0070562121 SfN 1998, Society for Neuroscience, The Mind-Body Link, Society for Neuroscience, http://web.sfn.org/content/Publications/BrainBriefings/mind.body.html Thibodeau 2002, Gary Thibodeau and Kevin Patton, The Human Body in Health & Disease, Mosby, 0323013384 Werner 2003a, Ruth Werner, Depression and the Stress Response System, Part I of III, Massage Today Magazine, http://www.massagetoday.com/archives/2003/08/10.html Werner 2003b, Ruth Werner, Depression and the Stress Response System, Part III, Massage Today Magazine, http://www.massagetoday.com/archives/2003/12/12.html All website pages were accessed between July and December 2005. 2005 Jessica Bale Why does massage make you feel good? Notes These notes are additional information I have found interesting but difficult to incorporate into my main text because of their added level of complexity. 1 The Na+/K+ ATPase ‘Na+/K+ ATPase is a pump that uses the energy from the hydrolysis of ATP to actively pump sodium and potassium ions against their concentration. The binding of three sodium ions to internal binding sites on the cytoplasmic side of the pump and phosphorylation of the pump induces a conformational change that releases the Na+ ions into the extracellular space. The subsequent binding of two potassium ions to the pump within the synapse followed by dephosphorylation causes it to return to its original confirmation and release the potassium ions into the cytoplasm. This pump is found in almost all cells of the body and the ionic gradient that it creates is used to carry out numerous important cellular processes, such as the transport of other molecules across membrane eg the monoamines.’ (CNS Forum 2003) 2 Serotonin and the gut ‘The serotonin in enterochromaffin cells is stored in subcellular granules that spontaneously release the amine into the adjacent lamina propria, which is endowed with at least 15 distinct serotonin receptor subtypes … Additional serotonin is released when the cells are stimulated either by increased intraluminal pressure, vagal stimulation, anaphylaxis, acidification of the duodenal lumen, or exposure to norepinephrine, acetylcholine, cholera toxin, or a variety of other chemical substances. ‘We now have extensive data (from studies of the serotonin antagonist 5-HTP-DP and anti-idiotypic antibodies that recognize 5-HT receptors) confirming that 1) serotonin stimulates the peristaltic reflex when it is applied to the mucosal surface of the bowel, 2) serotonin is released whenever the peristaltic reflex is initiated, and 3) the reflex is diminished when the mucosal source of serotonin is removed. Consequently, there is wide support for the hypothesis, first proposed by Edith Bülbring in 1958, that entero 2005 Jessica Bale Why does massage make you feel good? chromaffin cells act as pressure transducers and that the serotonin they secrete acts as a mediator to excite the mucosal afferent nerves, initiating the peristaltic reflex … ‘Provided that the vagus nerve is intact, a steady stream of messages flows back and forth between the brain and the gut. We all experience situations in which our brains cause our bowels to go into overdrive. But in fact, messages departing the gut outnumber the opposing traffic on the order of about nine to one. Satiety, nausea, the urge to vomit, abdominal pain--all are the gut's way of warning the brain of danger from ingested food or infectious pathogens. And while the brain normally responds with appropriate signals, the ENS can take over when necessary, as for example when vagal input has been surgically severed.’ (Gershon 2001) 3 Massage affects EEG symmetry ‘EEG asymmetry, specifically greater relative right frontal activation, is associated with negative affect. Depressed adults show stable patterns of this asymmetry. The present study assessed the effects of massage therapy and music therapy on frontal EEG asymmetry in depressed adolescents. Thirty adolescents with greater relative right frontal EEG activation and symptoms of depression were given either massage therapy (n = 14) or music therapy (n = 16). EEG was recorded for three-minute periods before, during, and after therapy. Frontal EEG asymmetry was significantly attenuated during and after the massage and music sessions.’ (Jones 1999) 4 Pain gate mechanism ‘In the case of sudden pain, the sudden pain fiber stimulates neuron X, causing a pain signal to be relayed to the brain. The sudden pain fiber also stimulates an interneuron (Y) that inhibits neuron X, after a brief delay. Thus, neuron X sends a pain signal to the brain for only a short time. In contrast, the slow pain fiber stimulates neuron X and inhibits interneuron Y. Thus, Y does not inhibit X, and X continues to send a pain signal to the brain, producing a slow, diffuse pain.’ (Sapolsky 2004) In contrast, if there is a dull, throbbing pain, stimulating the fast fibre quickly stimulates the Y interneuron which shuts down the system for a while. 2005 Jessica Bale