How Sweat Helps You Keep Your Cool
Gillian White BSc, MSc, PhD Candidate Department of Exercise Sciences, University of Toronto
How Sweat Helps You Keep Your Cool
As summer winds down and we are faced with the grim reality of fall, stress levels can increase as we settle back into the grind. While everyone has an individual motivation for why they exercise, from looking good to improving health or maybe socializing, most people agree that it has a profound impact on how they manage stress. Experts often promote movement breaks during the day to maximize productivity, while some fitness regimes are predicated on the idea that they’re anxiety reducing (i.e. yoga).
Whether its yoga to relax, kickboxing to vent frustrations, running to clear your head, or lifting weight to feel powerful – getting a good sweat seems to have universally beneficial influences on how we perceive and cope with stress. In fact, tested against cognitive/psychological interventions and pharmaceutical interventions, exercise holds its own as an effective anxiety and depression management tool (Wipfli et al., 2008).
But how does breaking a sweat actually help us chill? Is it all in our head or does it somehow make us stronger when facing life stresses?
Behind the Chill
Exercise is a form of physical stress – it takes our body out of “homeostasis”, our sort of physiological happy place, and causes adaptations to occur in an effort to cope with this disruption in both the short-term and the long-term. The changes that occur seem to be at the level of the body, as well as the brain. An important effect of exercise as it relates to stress is its ability to lower our anxiety sensitivity in both the short-term and the long-term. This is shown frequently in research as reductions in what is referred to as state-anxiety (how anxious we feel in response to an acute stressor) and trait-anxiety (how anxious we feel in general) (Petruzello et al., 1991).
In just a 2-week aerobic exercise intervention, Smits et al. (2008) showed reduced anxiety sensitivity in 88% of participants! Aerobic exercise has been frequently reported to reduce anxiety symptoms, depressive symptoms, and stress reactivity. While the bulk of research shows effects of acute and chronic aerobic exercise, similar results have also been shown in resistance training studies for both acute and chronic bouts (Strickland et al., 2014).
Interestingly, Medina et al. (2014) showed that men seem to benefit more from the anxiolytic (anxiety reducing) effects of aerobic exercise than females. Conversely, females seem to benefit more from anxiolytic benefits of resistance training (Strickland et al., 2014) – so not to worry, there is a stress reducing exercise regimen for everyone! Further evidence shows greater benefits for older individuals (65-75 years of age) compared with younger individuals and additive effects of a mixed aerobic and resistance training program.
And while this is great news for those of us who enjoy exercise, it may be even more important for people who don’t engage in regular exercise. People who experience a high level of stress are less likely to be active (Stutts-Kolehmainen et al., 2014), but exercise reduces the adverse effects of stress – this effectively compounds their risk of acquiring a stress-related illness.
Related Article: Manage Chronic Pain with Exercise
Stress & Exercise Physiology
‘Stress’ gets thrown around almost like a four-letter word in our society. But is it a good thing or a bad thing? Stress causes physiological release of hormones that increase heart rate, metabolic rate, and inflammation as the crux of our ‘fight or flight’ response – readying the body for action against some threat. However, when these systems are up-regulated chronically, like with poorly managed work or life stress, they cause those same systems to become dysfunction, ultimately leading to stress-related illnesses. To this end, having a stress system that can be up-regulated quickly to deal with a stressor but down-regulated quickly when the stressor has been dealt with is crucial for minimizing the negative effects of stress.
This might be exemplified by those colleagues you know that make it seem so easy to have a really stressful day at the office but somehow are able to leave it behind when the clock hits 5pm (or 9pm, depending on your work life). Exercise can help us develop this resilient way of responding to stress by improving how we buffer stress, optimizing our physiological responses to stress, and by changing our brain to interpret stressors differently (Silverman & Deuster, 2014).
Exercise as a Stress Buffer
An active coping strategy is exercise. When our stress or fear systems in the brain are activated, exercise can promote brain activation linked to motor circuits instead of fear/anxiety circuits (Charney, 2004). Endorphins released during exercise improve mood, as do increases in other precursors for feel good neurotransmitters. Physical activity also improves perceptions of self-efficacy and self-esteem. Consequently, this ultimately increases our sense of personal resources available to cope with future stressors making them seem less significant.
Increased blood flow to our brain allows enhanced clearance of metabolic wastes that build up during times of high brain exertion (i.e. stress), improving our ability to think clearly and facilitate problem solving. Overall, exercise improves how we interact with stress in the short-term such that it takes a less negative toll on us and is dealt with more effectively.
Exercise as a Stress Response Optimizer
People who have a greater stress response to a physical stressors (i.e. exercise) also have a greater stress response to psychological stressors. This means someone whose heart rate and breathing skyrocket climbing stairs is more likely to have a greater change in heart rate and stress hormones, as well as a greater perception of stress during a work or life challenges. Simply put, the inverse of this is people who are physically fit have reduced sensitivity to psychological stress. Essentially, exercise is a form of physical stress. Thus, when we exercise regularly, it acts as stress inoculation. This means small doses of stress (exercise) build up our tolerance to future stress exposure (a hectic work week).
By habituating our brain’s stress interpretation and activation regions, we reduce our perceptions of stress and our body’s response to a given stressor. There are other changes that occur at a more molecular level that include levels of hormones in the blood and receptor populations but it all shakes out to the same conclusion that exercise teaches our body how to respond to future stresses better.
Exercise as a Brain Changer
As discussed in greater detail in many articles on this cite, exercise is a potent means of inducing neurogenesis, or brain cell growth. Specifically, regions of the prefrontal cortex and hippocampus seem to be sensitive to these neurotrophic effects of exercise. These regions are also involved in stress restraining in the brain. The restraint imposed by these regions basically reduces the brain’s perception of how threatening a stressor is. As a result, one experiences lower feelings of anxiety and lower physical responses to that stressor.
These brain regions also govern our executive function. As a result, this encompasses problem solving, working memory, and attention. Hence, this gives us the tools to be more effective and productive. Overall this helps reduce how stressed out we feel when life throws your curve balls or a mountain of work to get through.
Related Article: Will Exercise Help the Brain Grow: Exercise and Ketones
Maximizing Stress Reduction
So while we now know how exercise helps us cope effectively with stress, what workouts should we throw into the rotation when work or life is putting us through the ringer:
Aerobic (based on Wipfli et al., 2008):
Moderate to high intensity (60-80% of age predicted max heart rate: 220-age = HRmax) – avoid exercise that is overly strenuous or exhausting, which can steal energy resources needed for thinking or coping with stress and excessively increase stress hormones in the blood exacerbating feelings of stress and anxiety. An intensity level should still be high enough to give you a good sweat.
20 minutes – 1 hour – same as above – depending on your fitness level, start with shorter duration and progress toward longer workouts to avoid becoming exhausted or more stressed.
Resistance training (based on Strickland et al., 2014):
Moderate intensity (40-70% of 1 rep maximum) – excessive weights can excessively increase stress hormones in the blood and cause mental fatigue exacerbating stress.
45 minutes – 1.5 hours – Ensure adequate rest between sets.
Of course maintaining a healthy work-life balance to avoid stress in the first place is probably the best way to keep yourself from pulling your hair out. Use exercise to deal with stress better in the moment. Furthermore, for future challenges, it will help you keep your cool.
Related Article: Endocannabinoids: The Secret to Why Exercise Makes Us Feel So Good
Charney, D.S. (2004). Psychobiological mechanisms of resilience and vulnerability: implications for successful adaptation to extreme stress. American Journal of Psychiatry, 161(2):195-216.
Medina, J.L., DeBoer, L.B., Davis, M.L., Rosenfield, D, Powers, M.B., Otto, M.W., & Smits, J.A.J. (2014). Gender moderates the effect of exercise on anxiety sensitivity. Mental Health & Physical Activity, 7(3): 147–151.
Petruzzello, S.J., Landers, D.M., Hatfield, B.D., Kubitz, K.A., & Salazar, W. (1991). A meta-analysis on the anxiety-reducing effects of acute and chronic exercise. Outcomes and mechanisms. Sports Medicine, 11(3):143-82.
Silverman, M.N., & Deuster, P.A. (2014). Biological mechanisms underlying the role of physical fitness in health and resilience. Interface Focus, 4: 20140040.
Smits J.A., Berry, A.C., Rosenfield, D., Powers, M.B., Behar, E., & Otto, M.W. (2008). Reducing anxiety sensitivity with exercise. Depression and Anxiety, 25(8):689–699.
Stults-Kolehmainen, M.A. & Sinha, R. (2014). The Effects of Stress on Physical Activity and Exercise. Sports Medicine, 44(1): 81–121.
Wipfli, B.M., Rethorst, C.D., & Landers D.M. (2008). The anxiolytic effects of exercise: a meta-analysis of randomized trials and dose-response analysis. Journal of Sport & Exercise Psychology, 30(4):392.
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