How and Why Yoga Helps with Pain

by Ram

Self Portrait with Bandaged Ear by Vincent van Gogh

Say, a heavy object fell on your big toe, or you cut your finger while peeling vegetables, or you applied alcohol over a bruise, or while walking down the street you twisted your ankle and immediately let out a shout—in all these situations, you have experienced an unpleasant feeling due to a tissue damage. When something harmful or irritating affects a part of our body, there is a biological response to try to remove it. This response takes the form of the unpleasant feeling/sensation called pain (see Yoga for Pain Management). 

The International Association for the Study of Pain defines pain as “an unpleasant sensory and emotional experience associated with actual or potential tissue damage.” You may ask why should anyone experience pain? Well, pain is part of the body’s inherent protective mechanism to:

• motivate you to pull out from a damaging situation and prevent further damage to the tissue
• allow the damaged tissue to rest and begin the healing process
• avoid similar encounters

Thus, you may appreciate the fact that pain is beneficial in a true sense when, for example, your back sustains a blow and the injured tissues need care and protection. Individuals who suffer from congenital insensitivity to the pain response are easily injured and most of them die at an early age. On the flip side, pain is a major symptom in several medical conditions that can interfere with a person's quality of life and general functioning as well see Interview with Shari and Bonnie on Pain Management). In these cases, pain turns out to be the most common reason for individuals to visit their physician.

Several classes of pain exist based on the initial stimulus and the site of damage:

1. Nociceptive pain (pain due to excess heat or cold; pain due to mechanical damage as in crushing, tearing; pain due to chemicals: pepper powder in the eyes; alcohol on bruises), 
2. Inflammatory pain (pain associated with acute or chronic inflammation—see Chronic Inflammation and Yoga)
3. Neuropathic pain (pain due to damage to nerves as in burning, tingling, stabbing, pins and needles, etc.)
4. Pathological pain (pain due to abnormal function such as arthritic pain, fibromyalgia, headaches, etc.)
5. Cancer pain (Cancer pain is complex as it constitutes a varied combination of pain types)

Just like inflammation, the phenomenon of pain is generally transient, and recedes when the stimulus is removed or the damaged tissue has healed. In a perfect setting or perfect body, pain occurs just as it should when needed, and turns off when the stimulus is withdrawn and the tissue has healed. However, there are certain abnormal pathological conditions where pain is a constant feature and persists for a long time. This is chronic pain that lasts beyond the expected period of healing. Unfortunately, chronic pain brings with it other health issues including constant fear, worry, anxiety, depression, and memory deficits. It is unclear if chronic pain triggers these co-morbidities or vice versa.

The entire process, starting from the initial stimulus to the actual pain response and the waning of the pain, involves several specialized receptors, neurochemicals, and transmission of the pain information through specialized channels. For example, if you cut your finger while chopping vegetables, this response triggers numerous events: a) mechanical stimulation from the sharp object, b) injury to the tissue, c) release of certain chemicals at the site of damage, d) signals from damaged tissue and the chemicals stimulate nerve endings found in the skin, muscle, joints, bone and viscera, e) information travels from the nerve endings to the spinal cord, for suitable action to be generated. The end result is the damaged area gets flooded by various inflammatory molecules and chemicals, including Histamine, Arachidonic acid, and Substance P, all of which trigger the pain response. Furthermore, when these pain signals traverse through certain areas of the brain, they stimulate a set of autonomic responses resulting in increased heart rate and blood pressure, rapid breathing and sweating.

Several factors can influence the pain perception including:

Age. As brain areas degenerate with age, brain circuitry also diminishes, so older people have lower pain tolerance and face severe problems dealing with pain.

Gender. In general, women have lower pain threshold and a higher sensitivity to pain. This could be due to hormonal changes that may be modifying the pain perception system.

Memory. Our past experience dealing with pain can influence neural responses to the incoming pain stimulus. 

Whether for acute or chronic pain, interventions include pain relievers/killers, including over-the-counter medicines like acetaminophen, nonsteroidal anti-inflammatory drugs (NSAIDs-Advil, Motrin), or prescription painkillers that are opium-like powerful drugs. Is there an alternate way to overcome pain, especially chronic pain? There are several studies that report the benefits of yoga in curbing pain. Yoga helps in the following ways: 

1. Yoga asanas trigger increased flow of oxygen to the brain and muscle tissues that improves energy levels and sense of wellbeing.
2. Yoga asanas help to release muscle tension and stretch the muscles thereby reducing the intensity of the pain
3. Yoga asanas can create more mental clarity thereby decreasing the level of perceived suffering
4. Yoga stress management practices, including meditation, focused relaxation, and relaxing asanas, help you cope with stress that can have a feedback effect on improving pain.

Furthermore, in animal models, research studies show that physical activity and a socially enriched environment reduce pain behavior. Similarly, studies in humans reveal that the practice of meditation and/or yoga reduces pain perception. Patients with chronic pain have accelerated, age-associated gray matter loss and decreased insular connectivity. The gray matter together with the associated insular areas plays important roles in emotion, perception, motor control, and self-awareness. It is not clear if pain triggers the gray matter loss and insular connectivity or vice versa.

In a recent study Insular Cortex Mediates Increased Pain Tolerance in Yoga Practitioners, a group of researchers concluded that yoga may prevent age-related gray matter loss and also increase intra-insular connectivity, thereby increasing the pain tolerance. The research study involved 14 experienced yoga practitioners and 14 individuals who did not have any practice of mind-body techniques (individuals were matched for gender, age, body mass index, left/right handedness, education, and exercise level other than yoga). The cold pain tolerance test involved immersing the hand in cold water until they could no longer tolerate the cold pain. The researchers conducted brain-imaging scans to examine the structural and functional differences in gray matter and white matter between the two groups. They also noted the strategies adopted by the individuals to tolerate the pain. The results were not very surprising: 

1. Yoga practitioners tolerated cold pain more than twice as long as the non-yoga individuals.
2. Researchers found a significant difference in gray matter volume in brain areas associated with pain processing, pain regulation, and attention.The increase in gray matter volume was associated with increases in the insular connectivity that correlated with the higher pain tolerance
3. Yoga practitioners had increased white matter (this would indicate extension of nerve fibers and improved nerve signaling). 
4. Yoga practitioners used various cognitive strategies to withstand the pain (such as observing the pain sensation but not reacting and using breath-relaxation techniques to accept the sensation) while most non yoga individuals were unable to think of such strategies. 

While definitive causal conclusions cannot be made, it is worthwhile to note that regular, long-term yoga practice seems to help individuals to deal with unpleasant sensory and emotional experience associated with pain. Take home message: Yoga In, Pain Out!

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