Stress and Anxiety Reduction (My Boss is a Mastodon)

From an evolutionary perspective, human brains evolved with an effective system to protect ourselves. In the face of danger, the brain calls the body to action with physiological responses enabling quick action. Your heart rate increases, blood pressure rises, and you feel a surge of energy. Commonly known as the fight or flight response, this automatic reaction loads the body and brain with adrenaline and cortisol in order to rapidly respond to threats. It works great for acute (temporary) stressful situations like running from predators, and kept us alive to see another day. The problem today is the response hasn’t quite learned the difference between a charging mastodon and a room full of peers waiting to hear your presentation. (And there’s where the urge to run out of the conference room came from.) If stress was meant to get us moving, it’s not a stretch to conclude that exercise is nature’s antidote to stress. And we have the science to support that assumption.

In our hunter-gatherer days, stresses were quickly resolved. We either got away or we didn’t. Today’s stresses are often prolonged and call for a cool head instead of a body ready for action. A looming deadline at work, a strained relationship, financial worries; the daily pressures of life are unavoidable. These pressures induce muscle tension, insomnia, sickness, and exhaustion on the mind and body, and can activate a vicious cycle in which the mind becomes stressed, inducing physical sickness, which, in turn, causes more stress. Just ask a bullied baboon. 

A study of baboons by Robert Sapolsky and his colleagues at Stanford University reveal the damages of chronic stress. Normally, baboons on the lower end of the social hierarchy keep their distance from dominant males. But, in a year of a booming baboon population, villagers in Kenya caged many of the animals to keep them from destroying their crops. The subordinate baboons were locked up with the dominate males (unable to exercise), and many died—apparently from stress. The unfortunate animals had ulcers, colitis and enlarged adrenal glands. Most notable, when their brains were examined scientists found extensive degeneration of neurons in their hippocampus, the area of the brain responsible for learning and memory. The chronic stress had grave effects on both their bodies and minds. Stress leads to the release of the steroid hormone cortisol. In the short term, cortisol helps the brain cope with the stress and actually improves cognitive performance. However, if too much of it hangs around for too long, cortisol begins destroying the connections between the nerve cells and leads to cell death, damaging the hippocampus and resembling the effects of aging on the brain, as was seen in the bullied baboons. Research has also clearly shown that chronic stress in humans prematurely ages the brain. (Bear, Connors and Paradiso, Neuroscience, Exploring the Brain, second edition 2001, pg 506)

Luckily, exercise can save the day. Exercise releases a host of neurochemicals and growth factors that reverse this process. May we introduce you to one of those neurochemicals; Meet BDNF (brain-derived neurotrophic factor), a superhero in the brain’s fight against stress. Present in the hippocampus, BDNF builds and maintains the cell circuitry of the brain, protects neurons against cell death and, this is significant, creates new neurons. Not long ago we thought we were born with a certain number of brain cells and that was it. The discovery that BDNF leads to neurogenesis (the birth of new brain cells) is, well, mind blowing. And exercise is one of the few ways known to increase BDNF in the hippocampus. John Ratey, clinical professor of psychiatry at Harvard Medical School and author of Spark: The Revolutionary New Science of Exercise and the Brain compares BDNF to ‘Miracle-Gro’ fertilizer for the brain. When researchers sprinkle BDNF on neurons in a petri dish, it causes them to sprout and grow new branches. Ratey explains: 

“At every level, from the microcellular to the psychological, exercise not only wards off the ill effects of chronic stress; it can also reverse them.  Studies show that if researchers exercise rats that have been chronically stressed, that activity makes the hippocampus grow back to its pre-shriveled state.  The mechanisms by which exercise changes how we think and feel are so much more effective than donuts, medicines and wine.  When you say you feel less stressed out after you go for a swim, or even a fast walk, you are.” (Ratey, Spark, pg 79)

Exercise not only counteracts the negative effects of current stress, it inoculates against future stress. Technically, exercise is itself a form of stress for body and brain, although mild. Just like muscles in the body, neurons in the brain are broken down and then built up again stronger than they were before. The stress of exercise helps the brain grow and become more resilient, enabling us to better handle the challenges of modern life. Michael Lehmann, PhD, at the National Institute of Mental Health illustrated this buffering effect of exercise in an experiment with mice. For three weeks, a group of mice were confined to small cages where little movement was possible. Then they were subjected to intimidation by more aggressive mice through a clear partition, and for a few minutes a day, the partition was lifted and the alpha mice had a chance to bully in person, sometimes needing to be restrained from harming the submissive mice. After two weeks, unsurprisingly, the submissive mice showed signs of depression and anxiety by hiding more and exploring less. In contrast, another group of mice lived in enriched environments for three weeks before they were introduced to the bullies. Here they could explore tubes and exercise on running wheels. Amazingly, these mice showed no signs of depression or anxiety when exposed to the aggressive mice. Exercise and mental enrichment seems to have a buffering effect on how we will respond to future stressors. (Lehmann, The Exercise Effect apa.org). 

Anxiety and depression are the ugly offspring of chronic stress. Relentless stress shifts brain chemistry making positive and realistic thoughts less accessible. (Ratey, Spark, loc 1076). Forty percent of adults will suffer from an anxiety disorder at some point in their lives. (https://www.anxiety.org/what-is-anxiety) Excessive feelings of uneasiness and apprehension, often with no discernable reason, seem unmanageable, leaving anxiety sufferers feeling out of control. Exercise effectively distracts the mind and interrupts the flow of worrying. Research shows it reduces muscle tension which reduces feelings of anxiety, and it eases the triggers of panic attacks. Symptoms of anxiety include heart palpitations, rapid breathing, and sweating--many of the same physical feelings of exercise. When a person experiences these physical sensations during exercise while they are controlling them, they connect them to a non-threatening situation conditioning the mind to feel safe (Ratey, Spark, pg 106-107).