In a previous post, I described the benefit of massage at the scene of the crime, so to speak, the site of the muscle injury. The mechanical deformation of tissue during massage causes reduction in local inflammation, increases the biogenesis of mitochondria, and accelerates the remodeling of the injured tissue.
But could that account for the emotional experience of massage? How could all these local effects cause the sense of relaxation and general well-being?
In short, they don’t.
It’s all in your head
To understand the general effects of massage, we need to examine the hormones and neurotransmitters that control mood. Now, like any physiological phenomenon, there are two sides to the effect of massage, not unlike the ancient Chinese concept of Yin and Yang.
Serotonin is a neurotransmitter that is secreted in the brain by specialized neurons (serotoninergic neurons). It regulates mood, hunger, and sleep and it promotes a sense of well-being and contentment.
Massage promotes the release of serotonin, which explains the positive mood effect, and the observation that despite vigorous manipulation people can fall asleep during a massage session.
There is another important effect of this substance. Blood platelets contain high concentrations of serotonin. When a tissue suffers any kind of trauma, such as small muscle tears caused by exercise, platelets accumulate at the injury site and release their serotonin.
This has several effects. It constricts the local small blood vessels—minimizing blood loss. It also attracts the cells that are involved in the healing process, accelerating the repair of the wounded tissue. (This is one reason why people with a low platelet count heal their wounds poorly.)
Dopamine is another neurotransmitter whose concentration is elevated by massage. The neurons that use dopamine as their chemical transmitter (dopaminergic neurons) make up the reward system in the brain. So massage induces the same sense of pleasure as sex, or a glass of wine, or on the darker side, a recreational drug such as heroin. No wonder some people are “addicted” to massage.
Oxytocin is the “love hormone”, and it is elevated in nursing mothers and people who fall in love. In general, it promotes the warm and fuzzy feeling. Alas, this effect is limited and fades with time, which may explain why most love affairs eventually cool off. Now, here is an intriguing observation. This hormone is released when massage is not vigorous, but rather gentle; the type you get in a spa, getting pampered.
Now to the other side of the Yin and Yang
Cortisol is a stress hormone. It causes constriction of blood vessels, leading to elevation of blood pressure. It also causes the death of NK cells (Natural Killer cells), a type of lymphocyte is the first line of defense against viral infection. It also inhibits several cells that are involved in wound healing. Massage reduces the levels of cortisol, reducing the physiological effects of stress, enhancing wound healing, and increasing immunity to viruses.
Epinephrine and norepinephrine (otherwise known as adrenaline and noradrenaline), are the hormones that mediate the fight-or-flight reaction to stress. Reduction of their levels results in lower heart rate, lower blood pressure, and elevated glucose metabolism. In short, all the good things we need for a sense of relaxation.
The objective evidence
How do you get objective evidence of a mood? Of feeling tense, or relaxed? These are highly subjective feelings and depend on self-reporting, which is notoriously unreliable. But we can get close to objective evidence by recording brain activity with an EEG.
Fluctuations in several types of brain waves associated with either relaxation or with waking up. Massage increases delta waves—the type of brainwaves linked with deep sleep—according to a study at the Touch Research Institute. Is this why it is so easy to fall asleep on the massage table?
As we said before, all physiological phenomena are the result of a balance between opposing influences. What massage does is tilt the balance away from stress and toward relaxation and healing. What’s not to like?
This post has been reposted from 02/07/12.