Issue link: https://www.massageandbodyworkdigital.com/i/108504
a normal range of 50–150 cells up to 800.8 As a result, we can claim that massage improves immune function. Still, the implications of basicscience research are not as tangible as in applied research. As yet, there is no definitive indicator of the mechanism behind massage therapy, and therefore no confirmation of our theories on how therapeutic touch works. As a result, we continue to use physiological markers to measure, rather than explain, the general benefits of massage. Cardiovascular markers such as blood pressure, heart rate, and heart rate variability show the effects of massage on anxiety, pain, and stress. Salivary cortisol levels may also demonstrate the benefits of massage on anxiety, pain, and stress, though whether or not massage plays a causative role in reducing cortisol is currently in question.9 Mechanisms for Gentle Touch In 2009, Merkel cells were confirmed as key in sensing light touch.10 Merkel cells are necessary for our hands to feel texture and shape, and to sense shifts as tissue softens and congestion eases. Without the ability to sense light touch, skilled handson therapy would not be possible. While studying the sense of touch, Duke University scientists pinpointed specific neurons that appear to regulate perception. The sensory neurons are characterized by thin spikes, and based on their volume, these protrusions determine the cell's sensitivity to force. This study discovered that the volume of filopodia—the spikes on class III neurons—influences the degree of sensitivity and that the filopodia can form, grow, or disappear in a matter of minutes.11 54 massage & bodywork march/april 2013 Duke professor W. Daniel Tracy says, "By learning more about touch sensing, we can begin to explore why these neurons become so responsive to stimuli and how it is that these signals become so painful. We might—in the long run—help people with chronic pain issues in new ways by looking at underlying molecular mechanisms." In a similar study at University of California at San Francisco, a world leader in brain research, scientists also identified the subset of nerve cells responsible for communicating gentle touch in fruit fly larvae. NOMPC, a particular protein found abundantly at the filopodia of class III neurons, was found to be the key to gentle-touch sensitivity in the flies.12 Identifying a neuron cell and its protein trigger in flies still leaves us with unanswered questions, such as what the analogous mechanism is in humans that confers gentle touch, or how NOMPC identifies touch or distinguishes between mechanical touch and human contact. But it helps researchers refine their strategies for studying gentle touch in humans. Most importantly, it prompts touch therapists to direct investigators to ask questions that can inform our practice. I continue to wonder how gentle, nonspecific touch can have similar effects on chronic pain as does deep touch targeted to the painful areas. Clinical Studies on Gentle Touch Let's look at some of the applied research studies on gentle touch and see what the results tell us. In a study at the University of Illinois at Chicago, a team of physical therapists worked with patients with multiple sclerosis (MS) to reduce grip force. Excessive gripping is common in those with MS and results in fatigue and decreased performance. Gentle touch applied to the affected hand was shown to significantly reduce the grip force required and regain control and coordination.13 In a study on preterm infants, the effects of two types of touch were analyzed in a neonatal intensive care unit in Iran: gentle human touch (GHT) and Yakson. With GHT, one hand is placed on the infant's head and one on the infant's abdomen. Yakson is a Korean technique using gentle touching and slow hand movement without pressure. Both were found to be equally beneficial in increasing sleep states and reducing fussy, awake states.14 And, in the above-referenced study comparing two types of massage therapy for chronic lowback pain, there was no clinically meaningful difference between the two types of massage in terms of relieving disability or symptoms.