Can exercise really beat anxiety? Can it be used as medicine to treat both the mind and body? According to an expert in brain health, Dr. Jennifer Heisz, the answer is a resounding “Yes.” Dr. Heisz is a neuroscientist, the Director of the NeuroFit Lab at McMaster University, and the author of the book, Move The Body, Heal The Mind: Overcome Anxiety, Depression, and Dementia and Improve Focus, Creativity and Sleep. Her award-winning research includes examining the effects of exercise on brain function to promote mental health and cognition in young adults, older adults, and individuals with Alzheimer’s disease.
Join us as we interview Dr. Heisz to discuss what most people do not know about how anxiety affects the brain and body and how exercise can clinically improve mental health. We also discuss how physical activity can boost the brain and improve mood and tips on the easiest ways to start your exercise journey – right now.
Victoria Sambursky: You talk about the power of anxiety in your book. Your write, “Anxiety distorts the mind and disables the body.” Can you discuss how parts of the brain have difficulty shutting off, even when the threat’s over?
Dr. Jennifer Heisz: “There is a center in the brain called the amygdala that regulates emotional processing and fear. It’s a threat detection center, and it has a direct line to the stress response in the body. So, for example, we can have a fearful thought that will trigger a stress response in the body. But then what happens is that stress response alters the body; it pushes it out of homeostasis, which then gets registered as another stressor by the amygdala. So it feels like, ‘oh my gosh,’ something else is wrong. So it creates this vicious cycle. We typically have our prefrontal cortex, which usually can calm us down. But when we’re in the anxiety cycle, the amygdala isolates itself from the rest of the brain and blocks communication from rational brain regions. And so it becomes this island where the threat and the fear can go unchecked. It’s tough to turn that off or get out of that.”
VS: With this understanding of the power of anxiety, in your book, you state: “Regular exercise can tone the stress response, making us less reactive to psychological stressors, even amidst seemingly uncontrollable situations.” How is this possible?
JH: “When we think about stress and its critical function, it’s very helpful for the body. But when it’s chronic, it starts to damage the body’s cells and the brain’s cells. One vital thing that gets damaged is the stress “off-switch.” This happens in the hippocampus; it has one of the off switches for the stress response. So when it gets damaged – we can’t turn off the stress response as readily; it stays on. And so what exercise does, first of all, it helps it increase growth factors like brain-derived neurotrophic factors (BDNF). These molecules go to that stress-off switch in the hippocampus, and it bathes the cells with this nourishing substance that protects them from stress. And then, they can re-engage and turn off the stress response.”
Dr. Heisz goes on to discuss additional positive adaptations that happen during exercise. She states, “So exercise is technically a stressor, right? But it’s an acute stress that we turn on, we turn off, and we know when it’s going to end. It’s controllable. And so, when we activate and deactivate the stress response, it’s almost like lifting a muscle. The stress response grows stronger. And because we only have one stress response for all stressors, we’re better able to tolerate the physical stress of exercise – but also the psychological stressors in our life. So it has that transfer effect. We’re now less reactive to stressors and better able to recover from them.”
VS: The vagus nerve runs through the body to the brain. It plays a key role in helping the body manage involuntary functions like heart rate and digestion. In the chapter on how stress makes you sick, you state, “The vagus nerve is like a sixth sense. It detects increases in inflammation, shifts in stress hormones, and even microscopic changes in gut microbiota diversity. But when the vagus nerve doesn’t shut off, you feel threatened and think negatively.” How can exercise help regulate the vagus nerve?
JH: The vagus nerve is part of the autonomic nervous system. And so, when we’re under stress, the sympathetic branch dominates, and the parasympathetic gets suppressed. The sympathetic branch is the fight or flight response. The parasympathetic is rest or digest, and the vagus nerve is involved in the parasympathetic. What exercise helps to do is strengthen the parasympathetic to lift heavier and heavier sympathetic loads. As it does this, your heart races less, and it helps bring your heart rate back down to baseline faster. Exercise is also anti-inflammatory. So each acute bout of exercise does increase inflammation a little. But then, immediately after exercising, the muscles release myokines [hormones produced by skeletal muscle tissue], which clean up all that inflammation. This action makes them anti-inflammatory. So as we consistently exercise, the body becomes less and less inflamed. This is important because inflammation impacts the health of the body and impacts mood. One way that inflammation impacts mood is that it alters the production of serotonin [the “feel-good” hormone]. Inflammation causes tryptophan – an amino acid and a precursor for serotonin – to break down or dysregulate. Inflammation does this by leading this amino acid towards a neurotoxic pathway that results in physical damage to the cells of the hippocampus and the amygdala. As a result, they cannot function optimally – making it difficult to shut off the stress response. This can result in a depressed mood and anxiety.” Dr. Heisz also mentions that exercise’s anti-inflammatory properties make it an effective treatment strategy for those who are depressed and don’t respond to anti-depressants.
VS: Best tips to help people get out of their heads and start moving?
JH: “Exercising is hard. And there’s a reason for this. The brain is actually working against you because it wants to conserve energy. This is a relic of our evolutionary past, where we needed to expend a lot of energy hunting and gathering our food. And it was imperative that we conserve energy that we didn’t have. So the brain sees voluntary exercises as an extravagant expense. And it goes out of its way to talk you out of that. So I think acknowledging that that will always be there is essential. But then, after we exercise, we feel so good. So building up the trust that it will feel good is crucial. Another way to start is to remember that some movement is better than none. Consistency is vital to finding a form of exercise that you enjoy, that will help you keep coming back to it – and then prioritizing that type of exercise. You need to make time for it in your calendar and respect that time like any other appointment.”
In Dr. Heisz’s book, she also mentions that light to moderate exercises, like walking, are enough, especially for people with anxiety. She suggests aiming for exercise that feels comfortably challenging, so your heart rate is elevated but not racing. However, she also helps readers train for a more health-conscious brain and offers step-by-step workouts to help optimize both the mind and body for better creativity, sleep, and focus.
