"Life is like riding a bicycle. To keep your balance, you must keep moving." Albert Einstein
Stress has become the demon of modern life. Lately, its presence looms large, especially with the hardships created by Covid, inflation, and the political as well as social upheaval in our culture. Stress has become so woven into our cultural consciousness that our understanding of what it is and how it affects us has become muddled. We are regularly reminded of the harmful effects of long-term exposure to stress, including cancer, heart disease, obesity, and Alzheimer’s disease. News feeds, documentaries, and social media all remind us of how stressful modern life can be. The rise in mindfulness practices such as meditation and breath training is a reflection of our collective effort to mitigate stress and establish calm in our lives.
What is lost in this obsession is that stress is not always harmful, and, in many ways, can be good for our health. We’ve all faced situations that require us to suddenly work harder and stay focused, from a looming work deadline to traffic on the beltway. These types of stressors are part of life, and exposure to them in the proper dose can help us develop coping skills that enable us to be more adaptable and resilient to future stressors. Stress is uncomfortable, but the right amount improves our performance, helps us stay focused, and fosters the vigilance required to navigate life with a balance of effort and ease.
Stress becomes harmful when the necessary effort and the demands of life chronically exceed our capacity to cope. A deadline, by itself, may be a motivating challenge, but becomes stressful if other unrelated pressures are added to the mix—your house is flooded, or your child is sick. There are no clear parameters that define when stress starts to erode one’s health. We all have our individual tipping points that fluctuate due to a number of factors, from a lack of sleep, illness, financial strains, or harmful thinking patterns. When it comes to stress, it is the dose that becomes the poison. Chronic, long-term exposure to feelings of being overwhelmed is the trigger that shifts stress from being beneficial to deadly.
Regardless of whether a stressor is psychological, emotional, chemical, or physical, the stress response follows the same biological pathway, creating the same measurable physiological response in the body regardless of whether a threat is real or imagined. In every stress response, the sympathetic nervous system (SNS) is stimulated, increasing our heart rate, elevating our breathing, and releasing hormones that get us ready to fight or flee. This heightened physiological state is uncomfortable and goes against the grain of the body’s preferred mode of operating, which is having all its systems humming along smoothly within an optimal range. Once the stress response is initiated, the body takes action to reestablish stability. Our body is designed to be stress responsive, with mechanisms that enable systems to be adaptable and resilient, able to respond efficiently to the predictable and unpredictable stressors of life. Provided we are not overwhelmed, regular exposure to the changes initiated by activation of the SNS strengthens the body’s ability to maintain stability when faced with adverse or stressful situations.
Exercise is a planned, intentional dose of stress designed to tip certain body systems out of balance with the intention of enhancing their capacity to regain stability in response to stressors. This may sound a bit obtuse, but it is quite understandable when put into practice. Imagine that you start a walk at a slow pace. At a low level of effort, the demands on the body are light and there is not much that needs to change. Your breathing is steady, you can talk without much effort, and your muscles are not necessarily challenged. Things change when you pick up your pace. Your breathing becomes labored, your heart rate rises, and your muscles start to work harder. Perhaps you start to sweat. You notice the change in effort and feel discomfort. However, after a period of time at an increased pace, you may notice that you don’t feel quite as uncomfortable. Perhaps you have fallen into a groove in which you are aware of the work but can sustain the effort. What happened? Your body responds to the change by ramping up the cardiovascular and respiratory systems so that you can continue the work at a recalculated steady state, one that is higher than resting but remains stable over time. With repeated exposure to this type of stress, our body’s capacity to respond to an increased workload is enhanced, eventually making that brisk pace seem less uncomfortable and easier to maintain.
Physical activity is critical for our health, but it differs from exercise in its intensity and intention. Exercise is a special subset of physical activity, with different forms targeting different body systems. Cardiovascular exercise—what is referred to as “aerobic” exercise—specifically conditions the heart, circulatory, respiratory, and metabolic systems. Aerobic exercise involves rhythmic movements that elevate the heart rate for a sustained period of time. The effort can be light, moderate, or high and includes activities such as walking, running, cycling, swimming, hiking, and even dancing. A key distinction between aerobic exercise and physical activity is the elevation of one’s heart rate and the increased demands placed on breathing, the circulatory system, and energy metabolism. A detailed description of all the physiological changes that occur with aerobic exercise—they are quite extensive and sophisticated--is beyond the scope of this blog. While we need not be aware of the exact physiological changes, it is important to recognize the increased demands aerobic exercise puts on our cardiovascular, respiratory, and metabolic systems, as these are the changes that distinguish it from physical activity and give it the power to improve our health.
Generally, most of us lack appreciation of the role these increased demands play in our well-being, obscured by our cultural focus on the calories associated with a given exercise. Caloric expenditure is a somewhat vague estimate assigned to a given activity based on algorithms related to age, heart rate, and estimated metabolic requirements. Specific measurements of caloric expenditure can only be obtained with sophisticated diagnostic equipment. Focusing only on calories overlooks the important role exercise plays in building our capacity to establish stability within change--it builds our immunity to stress. Applied in the right dose, the stress of exercise makes our heart more pliable, our blood vessels more supple, our breathing muscles more responsive, and our lungs more efficient. It stimulates numerous positive metabolic processes and significantly improves brain functioning. When we consider all the important and vital changes regular exercise stimulates, caloric expenditure fades into the background, becoming an inconsequential sidebar.
High intensity training is a form of aerobic exercise that has gotten a great deal of attention over the past several years. It involves short bursts of hard exercise, performed at a very high level of intensity, followed by a period of rest. This type of cardiovascular exercise is appealing because it can be done in a short period of time while delivering numerous benefits. The sudden change in intensity that is characteristic of high intensity training has been shown to enhance the heart’s resilience. This is measured as Heart Rate Variability, which reflects the heart’s ability to shift rapidly from high levels of work to recovery. The greater the variability, the more resilient the heart tissue. It has also been found to promote the production of so-called “good” cholesterol (HDL). The downside of this type of training is that it is highly dose dependent. When done more than once or twice a week, it makes us more susceptible to injury and burnout, and can lead to detrimental physiological changes related to stress overload. In small doses, however, this type of training builds the body’s ability to bounce back in the face of a challenge.
Perhaps one of the most underrated benefits of regular aerobic exercise is its downstream effect on our emotional and psychological health. Studies show that regular, moderate intensity aerobic exercise not only strengthens our body’s ability to manage stressors, it also enhances our mind’s self-regulation and coping skills. It seems that as our body systems become more adaptable and resilient, so do our thinking processes. And changes in the brain are not simply metaphorical, but neurophysiological. Regular aerobic exercise initiates the production of brain-derived neurotrophic factor (BDNF), which promotes the growth, functioning, and longevity of brain cells. BDNF protects the brain against the toxic effects of high stress while expanding our brain’s capacity to learn new coping mechanisms. In this way, our body can teach us something that our minds might resist.
A well-known Buddhist saying reminds us that the journey through life includes ten thousand joys and ten thousand sorrows. We can never know what those sorrows will be, but we can take steps to help build our capacity to adapt and bounce back from stressors, hardships, and even tragedy. Our bodies can serve as a powerful means to build our immunity to stress both physically and mentally. Aerobic exercise, with its focus on placing intentional stress on the body systems that are intimately related to our existence—the heart, lungs, and circulation--can be our best teacher in preparing us to face our sorrows. Are you up to the challenge?
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