For this study, 110 children between the ages of 10-13 wore sensors to detect their daily movements over a one-week period. The children were also brought into the lab on two separate occasions to complete both a stressful task and a non-stressful control task, as well as physical stress reaction testing via cortisol in their saliva. Additionally, cognitive reactions to the stress tasks were recorded by brainwaves using an EEG.
During stress testing, the children had to read an open-ended story and then had five minutes to prepare using their notes to tell the rest of the story to a jury. This task was followed by an arithmetic task in which they had to repeatedly reduce a number in the high three digits by a certain value over 5 minutes. The control task was conducted on a separate occasion, it also involved reading a story, but this time they only discussed general questions with one researcher without any pressure to perform.
“We wanted to determine whether physical activity makes children more resilient under laboratory-controlled circumstances,” explains project director Sebastian Ludyga. The results showed that the participants who got more than an hour of exercise per day, as the World Health Organization (W.H.O.) recommends, did in fact produce less cortisol in the stress task than the children who were less active.
“Regularly active children seem to have a reduced physiological stress reaction in general,” notes Manuel Hanke, lead author of the study. Even in the control task, which involved an unfamiliar situation, making it still somewhat unsettling for the participants, there was a difference in cortisol levels between more and less active children — though overall cortisol levels were lower than in the stress task.
“When children regularly run, swim, climb, etc., the brain learns to associate a rise in cortisol with something positive. The body’s reaction always has a cognitive component as well: this positive association helps to prevent the concentration of cortisol from rising to too high a level in exam situations as well,” said Sebastian Ludyga.
“Stress can interfere with thinking. Some of us are familiar with this in its most extreme form — a blackout,” Hanke explains.
