"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 ofper day, as the World Health Organization 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.
Besides their analysis of the saliva samples, the researchers also examined cognitive reactions to the stress task by recording participants' brainwaves via electroencephalogram . The team plans to analyze these data next."Stress can interfere with thinking. Some of us are familiar with this in its most extreme form—a blackout," Hanke explains.
After about a minute, their notes were mostly exhausted but they still had to fill five minutes and think something up on the spur of the moment. This task was followed by a seemingly simple arithmetic task in which participants were asked to repeatedly reduce a number in the high three digits by a certain value over the course of five minutes.
The stress in this task is primarily caused by errors, which require the participant to restart the task from the beginning. In the control task, which was conducted on a separate occasion, the children also had to read a story, but they then discussed general questions about the story with a researcher without any pressure to perform. In both sessions, the researchers took saliva samples at