It’s well known that exercise makes us happier. This is usually attributed to a vague notion of “endorphins” and is generally left at that. In The Joy of Movement, health psychologist, Dr. Kelly McGonigal, paints a much richer picture. In it, she elucidates the extraordinary physiologic mechanisms that lead to exercise-induced psychological well-being.
Dr. Kelly McGonigal has one of my favorite brains. She’s optimistic yet rigorous and takes well-worn topics that seem basic and overplayed and flips them on their head (for an example of this check out her ted talk on why stress may be good for you).
In The Joy of Movement McGonigal takes the topic of exercise, which is so popular it can seem mundane, and through thoughtful narration and groundbreaking research, she makes exercise feel like the most cutting edge, novel intervention around.
These are the 4 most mind-blowing facts I learned from her book. I’m just skimming the surface here so I highly recommend grabbing your own copy.
Top 4 Ways Exercise Changes Your Brain:
#1 Beyond endorphins..exercise and the endocannabinoid system.
New research shows that the legendary “runner’s high” is likely not due to endorphins, but rather endocannabinoids. Endocannabinoids are the cannabis-like molecules produced within our bodies. Endocannabinoids are small enough to cross the blood-brain-barrier in order to confer psychological benefits.
The brain is rich in endocannabinoid receptors, particularly in the brain regions responsible for our stress response. When released following sustained moderate aerobic exercise, these molecules reduce anxiety, increasing feelings of contentment, increase dopamine, and make us feel more socially open and connected to others.
According to McGonigal, in order to experience the endocannabinoid release from exercise, you must do moderate-intensity movement (like fast walking, jogging, swimming, etc.) for at least 20 minutes. It is likely that we evolved with this built-in reward signal to motivate us to endure sustained walking and running during our history as persistence hunters-gathers, who often had to move all day in order to eat and survive.
As our country tries to square marijuana’s potential medicinal properties with its ambiguous legal status, exercise offers a readily accessible, natural way to play with our own endogenous cannabinoid molecules and reap its medicinal rewards.
#2 Your muscles are endocrine glands that release “hope molecules”
In our muscle obsessed culture, it feels odd to say that muscles are underrated. Yet, in addition to their more well-known properties, new research shows that your skeletal muscles also function as endocrine glands that produce mood-boosting hormones some scientists emphatically call “hope molecules”. These are released into the bloodstream every time the muscles contract. This class of molecules is known as myokines there are many different types being discovered that provide different health-boosting effects.
Some myokine-related benefits that McGonigal highlights in the book include, protection and regeneration of neurons, stress resilience, decreased brain inflammation, and neutralizing a neurotoxic chemical caused by chronically elevated stress hormones before it reaches the brain.
Knowing that every muscle contraction provides my brain and body with a steady drip of mood and health-boosting molecules motivates me to seize every opportunity to move.
#3 Your step count is directly correlated with anxiety and depression.
The average American takes 4,774 steps a day. I read this stat in McGonigal’s book while in a somewhat depressive mood at the end of a long workday. My pedometer read 4,200.
Research has shown that the average daily step count required to induce feelings of anxiety and depression and decrease satisfaction with life is 5,649. When adults were randomly assigned to reduce their daily step count, 88 percent become more depressed, indicating a causal link between walking and mood.
There are many compelling reasons to shoot for a goal of 10,000 steps a day but if mood regulation and brain health are a priority, make 6,000 your bare minimum goal.
#4. Outdoor exercise = instant meditation
There is something about outdoor exercise. Many of us “hate the gym” and prefer getting outside to crowded, dimly lit, TV-centric gyms. Beyond the obvious, McGonigal helps us understand why.
“Green exercise” aka movement done in outdoor spaces has been studied by psychologists. “Green exercise” appears to change our brains in unique ways. And unlike some of the endorphin or endocannabinoid benefits of exercise which take a little while to kick in, the benefits of “green exercise” appear to be more immediate. This may be because green spaces help our brain disengage from the default mode network (the DMN).
The default mode network is having a moment and you may have heard about it as it relates to depression, meditation, and psychedelics. Here’s a default mode network primer: according to McGonigal the DMN is the brain network when the human mind is not focused on anything and is allowed to wander. It’s the brain’s state at baseline. When in this state, the mind is mostly self-referential and focused on analyzing your social relationships and standing.
There is nothing inherently wrong with the default mode network, but it often has a negativity bias and when overactive it feels like anxious rumination. People with anxiety and depression tend to have an overactive DMN and as such, many of the latest cutting edge treatments for depression like Ketamine and transcranial magnetic stimulation deliver their benefits by decreasing overactivity in the default mode network. Additionally, tools like meditation and psychedelics also appear to reduce activity in the default mode network, which can lead to a feeling of selflessness, lack of self-consciousness, and a deeper connection to others and to nature. Similar to entheogens, meditation, and cutting-edge depression treatments, outdoor exercise naturally and quickly quiets the DMN. For those of us that have trouble “quieting our minds” this is an invaluable tool.
McGonigal dives deeper and proposes a fascinating new take on the default mode network. She proposes that the traditional DMN we hear about (the self-focused one) may not be the only “default” our brains have. Drawing on the work of Dr. Alexandra Rosati, a psychologist who studies how the human mind developed, she posits that we may have two distinct defaults. Which “default” we reside in is likely context dependent.
McGonigal cites two primary pressures that influenced our brain development throughout evolutionary history; social cohesion and the need to get food from our natural environment. The latter influence explain the “second default mode” that takes over in natural environments. She calls it “foraging cognition”. McGonigal posits that we likely evolved with these two default modes but as indoor, screen-focused modern humans, we don’t often access this second nature-focused default mode and over-activate the self-focused network. This is why getting outside and moving can feel like such a relief. We are meant to spend ample time in both states of mind.
This helps explain our current craze of seeking things like meditation, psychedelics and other entheogens, and pharmaceuticals that help us access our second neurological home. Unfortunately, psychedelics are still illegal and meditation takes some skill and commitment in order to reap the benefits. “Green exercise” appears to confer similar neurological and psychological benefits to these more controversial modalities naturally and for free. And luckily, we can bypass all the hype, zip past the regulatory barriers and soothe our ruminative brains immediately. Simply step outside, move your body, and gaze at your surroundings.