The evidence that physical activity is good for people of all ages both physically and mentally continues to mount. Finnish researchers have conducted an experiment showing that physically active children are likely more capable of handling everyday stress than their less active peers. Highly active children showed lower levels of cortisol, a hormone produced in response to stress, after exposure to arithmetic tests and storytelling. Their less active peers, on the other hand, showed surging cortisol levels, further underscoring the mental benefits of maintaining a healthy and active lifestyle.
The Stress Hormone
Cortisol, a hormone naturally produced by the adrenal cortex is involved in blood pressure maintenance, inflammation reduction, the stabilization of blood sugar levels, as well as contributing to a healthy immune system. Physical and psychological stresses release cortisol. In fact, cortisol is so closely linked with stress that it is also known as “the stress hormone.” At high levels, cortisol can be responsible for many symptoms commonly linked to heightened levels of stress, including:
- Stomach issues (including ulcers)
- Weakened immune system
- Memory and concentration impairment
For this experiment, led by Silja Martikainen, MA, of the University of Helsinki, Finland, the researchers monitored 258 children’s physical activity through wrist-worn accelerometers for a minimum of four days, and their levels of salivary cortisol over the same period. The researchers then divided the children into three groups according to their level of physical activity. Finally, the children were exposed to various storytelling situations and arithmetic puzzles in order to induce stress, and had their cortisol levels measured afterwards.
Although there was no difference in cortisol levels between physically active and sedentary children while in their home environment, things changed significantly when the children were exposed to medically and scientifically approved stress tests. Children in the highest physical activity category showed little to no increase in their measured cortisol levels after being exposed to stress, whereas the moderately and least active children showed significant to high increases. In other words, children who were physically active have a better physiological response to stress.
Limitations of Study
Some researchers caution that persistently heightened cortisol levels may be a better indicator of a child’s response to stress than the single-measurement comparisons used in this experiment, and that sugar intake, which is also linked to cortisol production, was not controlled for. Additionally, accelerometers may not adequately measure some physical activities, such as swimming or bicycling. Nevertheless, the study’s authors are confident their work demonstrates a physiological response to stress than may be mitigated through increased physical activity.
Higher levels of physical activity are associated with lower hypothalamic-pituitary-adrenocortical axis reactivity to psychosocial stress in children, Martikainen, S., et al., 2013 In : Journal of Clinical Endocrinology and Metabolism. 98, 4, p. E619-E627 9 p.
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