Our modern-day society is split between two types of people: The regular gym visitors and the ordinary mortals, who cancel their gym membership two months into the new year. We all know exercise is healthy for our body (there, I said it!) but we often disregard its effect on mental health, our ability to manage stress and cope with problems. If impaired, one can suffer from symptoms of low motivation, depressed mood, decreased self-esteem and even clinical depression. If you are feeling under the weather lately, this might be linked to your lack of exercise – but how exactly does that work?
Our lifestyle has outgrown the need for daily exercise (Big thanks to science and technology). However, our body hasn’t! We still possess the same genetic makeup as our Palaeolithic ancestors, who’ve travelled hundreds of miles while hunting and scavenging. The rising numbers of patients suffering from mental illnesses and neurodegenerative diseases like Alzheimer’s disease are tightly linked to our sedentary lifestyle. Exercise has been shown to benefit prevention and treatment of neurodegenerative diseases, as well as mental diseases such as depression and anxiety (Deslandes et al., 2009; Portugal et al., 2013). Some scientists even suggest that exercise might have similar biological effects on the brain as antidepressants and can boost the effectiveness of the primary therapies such as medication and psychotherapy (Bornebekk 2005; Peluso & Andrade, 2005; Portugal et al., 2013)
As of now, there is no singular underlying mechanism known. It’s much more likely that there are several mechanisms responsible for the positive effects of exercise on our brain:
You have probably heard of the “runners high”, which describes the euphoria athletes experience during an exhausting exercise session. This phenomenon is induced by the exercise-driven release of hormones called endorphins – which are hormones known to induce a sense of pleasure and relaxation as well as reducing stress and feelings of pain. The reported effects of elevated mood and stress and anxiety relief subjects experience upon undertaking exercise might be attributed to that surge of endorphins (Mikkelsen et al., 2017).
Longer lasting positive effects of exercise such as improved mood and an upsurge in self-esteem and vitality might be attributed to shifts in signalling molecule levels associated with motivation and happiness such as such as dopamine and serotonin. Also, the increase of serotonin and noradrenalin levels seems to act like antidepressants, counteracting imbalance of these neurotransmitters reported in depressive patients (Mikkelsen et al., 2017).
Neurotrophic factors – which are molecules that support the survival and growth of nerve cells – are produced in muscles of individuals who are physically active. These factors are for example: The brain-derived neurotrophic factor or insulin-like growth factor, which are known to modulate synaptic plasticity and neurogenesis and therefore, most likely outbalance effects of neurodegenerative diseases like Alzheimer’s and Parkinson’s disease (Deslandes et al., 2009).
There are several other physiological mechanisms like reducing the activity of the neuroendocrine system that controls reactions to stress, which could explain the effects of exercise on the brain. However psychological effects of exercise might have just as big impact as physiological ones: The feelings of achievement and self-esteem generated by being active as well as the social aspects of sports greatly contribute to the positive effects exercise poses on our mental health. Some scientists suggest that the mental “time out” during the exercise is responsible for the mood-altering effects.
Effects of Exercise on the Brain
Studies show that exercise results in several different changes in brain chemistry that might explain the described effects of acute and regular exercise on our mental health
A recent study showed that moderate exercise led to a 43% reduction of self-reported bad mental health days. However, there is such thing as exercising too hard! Training more than 3 hours per day led to a decrease of mental health even worse than doing no exercise at all (Chekroud et al., 2018).
Poor exercise conditions like over-exhaustion or dehydration push the body to break down amino acids to generate energy instead of carbs and fats. When the body uses amino acids as energy source, ammonium ions are accumulated. These molecules are neurotoxic; they decrease blood circulation in the brain and reduce the level of neurotransmitters like serotonin and dopamine (remember, those were the signalling molecules related to mood uplift). Therefore, overtraining leads to adverse effects like depressed mood, decreased self-esteem and motivation as well as loss of appetite and disturbed sleep (Peluso & Andrade, 2005; Portugal et al., 2013). But don’t worry, overtraining syndrome is typically easily curable by allowing the body a few weeks or months of rest (Chekroud et al., 2018).
There seems to be an inverted u-shaped relationship between exercise intensity and affective state. Optimal intensity of workout leads to the highest beneficial effects, while every action above that is registered by the body as a threat and therefore generates a negative affective state. This optimal intensity is near the ventilatory threshold, meaning: If you are still able to speak during workout, you should be fine.
While every person is unique and therefore needs their own exercise regimen, the US guidelines for physical activity might give you a pointer in the right direction: For adults between 18 and 64 years they suggest two sessions of strength exercise per week as well as a minimum of 150 minutes a week of aerobic exercise – which are activities that aim for endurance like jogging, riding a bike, dancing, or swimming (Deslandes et al., 2009). These directions are also the ones that most often come up in study designs and are therefore shown to be an effective treatment for clinical depression, reducing the risk of Parkinson’s disease, decrease the number of anxiety attacks as well as increasing general well-being (Chekroud et al., 2018).
Evidence differs on which intensity workouts are considered the most pleasurable. Either high intensity exercises like running or swimming laps, or medium intensity which are exercises where you can still have conversations like walking briskly or active forms of yoga. There probably is no right or wrong – most studies conclude that most pleasure is felt, and the best behavioural outcomes are achieved when the subjects were able to decide on the intensity of the workout themselves.
There is no “one-size-fits-all approach” when planning your exercise regimen, however, there is one universal trick to raise your performance while moving: Distraction! So, put on that motivational music and get exercising.
Your brain will thank you later!
Main literature
Bjørnebekk, A., Mathé, A. A., & Brené, S. (2005). The antidepressant effect of running is associated with increased hippocampal cell proliferation. The International Journal of Neuropsychopharmacology, 8(3), 357–368. https://doi.org/10.1017/S1461145705005122
Chekroud, S. R., Gueorguieva, R., Zheutlin, A. B., Paulus, M., Krumholz, H. M., Krystal, J. H., & Chekroud, A. M. (2018). Association between physical exercise and mental health in 1·2 million individuals in the USA between 2011 and 2015: A cross-sectional study. The Lancet Psychiatry, 5(9), 739–746. https://doi.org/10.1016/S2215-0366(18)30227-X
Deslandes, A., Moraes, H., Ferreira, C., Veiga, H., Silveira, H., Mouta, R., Pompeu, F. A. M. S., Coutinho, E. S. F., & Laks, J. (2009). Exercise and Mental Health: Many Reasons to Move. Neuropsychobiology, 59(4), 191–198. https://doi.org/10.1159/000223730
Mikkelsen, K., Stojanovska, L., Polenakovic, M., Bosevski, M., & Apostolopoulos, V. (2017). Exercise and mental health. Maturitas, 106, 48–56. https://doi.org/10.1016/j.maturitas.2017.09.003
Peluso, M. A. M., & Andrade, L. H. S. G. de. (2005). Physical activity and mental health: The association between exercise and mood. Clinics, 60(1), 61–70. https://doi.org/10.1590/S1807-59322005000100012
Portugal, E. M. M., Cevada, T., Monteiro-Junior, R. S., Guimarães, T. T., Rubini, E. da C., Lattari, E., Blois, C., & Deslandes, A. C. (2013). Neuroscience of Exercise: From Neurobiology Mechanisms to Mental Health. Neuropsychobiology, 68(1), 1–14. https://doi.org/10.1159/000350946
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