Part I: What is stress and how does it affect us?

Part II: Can yoga mitigate the effects of stress (distress) on our health and wellbeing? An exploration of evidence and practical application (August 2012)

Perhaps one of the most remarkable things about living on the planet at this time is our unparalleled access to the rest of the world. We are literally tapped in to a global web of technology, communication, information and ideas. The beauty of this is that our knowledge is growing exponentially every day, and with that our hunger to see, feel and understand more. The flip side of this is that knowledge doesn’t equal wisdom – and while we feed our increasing hunger for stimulation, our body pays the price.

The health costs of being overwhelmed or “stressed” are increasingly examined, especially as growing numbers of the population are self-identifying as being stressed out, anxious or depressed. According to the Canadian Mental Health Association, 20% of the population will personally experience some form of mental illness in their lifetime. Further to this, Health Canada has noted that “Stress” is a risk factor in heart disease, some bowel diseases, herpes, and mental illness, as well as a complicating factor in diabetes.

Yoga teachers and practitioners often claim that practicing yoga (asana, meditation, pranayama and svadhyaya) modifies both stress levels and the deleterious effects of stress on the body. Fortunately, Yoga Therapists are more consistently conducting evidence-based research, through which we can examine these claims. This research will allow us to intelligently apply yoga practices to the individual and ideally achieve measurable results.

What is Stress?

“Stress is a biological term which refers to the consequences of the failure of a human or animal to respond appropriately to emotional or physical threats to the organism, whether actual or imagined. It includes a state of alarm and adrenaline production, short-term resistance as a coping mechanism, and exhaustion. Common stress symptoms include irritability, muscular tension, inability to concentrate and a variety of physical reactions, such as headaches and elevated heart rate.”[i] (Hans Selye)

The fascinating aspect of this definition is that it identifies that our stressors can be “real or imagined”. This indicates that there will be a physiological response even if we are only imagining a stressful scenario.

Hans Selye (founder of the Canadian Institute of Stress) further outlined Stress via his model of General Adaptation Syndrome, which looks at how we manage or tolerate stressors over time;

Stage 1: Alarm: Activation of the Sympathetic Nervous System and secretion of Cortisol.

Stage 2: Resistance: The body attempts to adapt to a persistent stressor and resources gradually deplete.

Stage 3: Exhaustion: The resources of the body are depleted and normal function is impaired. Long term damage may result from extended stimulation of the organs and impairment of the immune system. This may present as: ulcers, depression, diabetes, digestive disorders, cardiovascular disease and mental illness.

Interestingly, Selye found that stress can be divided into two general categories:

Eustress: stress that enhances function (i.e.: Exercise).

Distress: depresses function and leads to the presentation of physical and mental disorders.

Stress is modified through perspective (our perception of events), relaxation of the sympathetic nervous system and facilitation of the parasympathetic nervous system.

Symptoms of Stress:

Dr. Earle, the current director of the Canadian Institute for Stress advises that anyone experiencing two or more of these symptoms on a regular basis should take steps to decrease stressors in their lives.

Stress and the Brain:

According to McEwen (2008), the brain determines what is stressful as well as our physical and behavioural response to actual/potential stressors.[ii]

The brain initiates three general pathways in order to defend itself against stress:

1. Hormones: uppers, modulators and downers (i.e.: epinephrine, nor-epinephrine and cortisol)
2. Inflammatory Cytokines: They may be Pro- or Anti-inflammatory
3. Sympathetic Nervous System: “Fight, Flight, Freeze, Play Dead response” Versus Parasympathetic Nervous System: “Rest and Digest response”.

Sympathetic Nervous System

• The sympathetic nervous system (SNS) supports the whole body in its flight or fight function by gearing up the internal organs and musculature for emergencies.[iii]
• This stimulation of the nervous system occurs when our senses detect either danger or the need to be alert.
• Epinephrine (adrenalin) is released from the adrenal medulla in response to the SNS.  It activates the body globally when stimulated.[iv]
• Cortisol is also released, which is a corticosteroid hormone produced by the adrenal cortex. It increases blood pressure and blood sugar, and reduces immune responses.
• The heart rate increases.
• Respiration rate increases.
• Glucose is released from the liver for energy.
• Pupils dilate.
• Arterioles constrict in the digestive system and skin so that blood is shunted away from these areas (increases blood pressure). The hands and feet become cold due to the vasoconstriction.
• Sweat glands flood the surface of the body making the skin clammy.
• Arterioles in the heart dilate.
• Sphincters in the GI tract constrict.
• The senses become sharper.
• These physical changes increase your strength and stamina, speed your reaction time, and enhance your focus – preparing you to either fight or flee from the danger at hand.

Parasympathetic Nervous System

• The Parasympathetic Nervous System (PNS) is the complementary partner to the SNS in the autonomic nervous system.  It is the “Rest & Digest” response.
• In contrast to the SNS which is global, the PNS is organ specific.[v]
• In relation to the SNS the PNS only balances out functions of respiration and heart rate.  Otherwise it presides over specific organ functions.
• Stimulates digestion by facilitating peristalsis, and production of saliva and digestive enzymes.
• Stimulates sexual arousal.
• Slows heart and respiratory rate.
• Facilitates elimination.
• Parasympathetic activity has anti-inflammatory effects.

Part II: Can yoga mitigate the effects of stress (distress) on our health and wellbeing? An exploration of evidence and practical application (August 2012)