Physical fitness, physical activity and screen time are tied to adolescents’ brain function

Physical fitness, physical activity and screen time are associated with brain mechanisms underlying mental health and learning, according to two recent studies from the University of Eastern Finland and Kuopio University Hospital. Research into the effects of lifestyle and physical fitness on adolescent brain function remains limited to date.

“Our new findings highlight the importance of an active lifestyle, good physical fitness and moderate screen time for brain development in adolescence,” says Doctoral Researcher Hannamari Skog from the Institute of Biomedicine at the University of Eastern Finland.

The quality of screen time matters

In the first study, published in Frontiers in Neuroscience, participants’ physical fitness and lifestyle habits were monitored from childhood. The researchers found that better physical fitness was associated with increased excitability and stronger inhibition of the motor cortex in adolescence—with excitability and inhibition regulating brain development and learning processes.

The second study, published in Neuroscience, examined the associations of screen time and physical activity with brain function. According to the results, the amount of screen time is not the sole critical factor for brain development, but the way people engage with various digital devices also plays a significant role.

“Passive engagement with digital devices, such as scrolling on the phone or watching TV and videos, weakened adolescents’ cortical inhibition, that is, the so-called ‘braking system’ of the brain,” Skog says.

Conversely, active engagement with digital devices was associated with increased cortical excitability, as was participation in organized sports in sports clubs.

According to Skog, it is beneficial for adolescents to have access to organized sports:

“Besides supporting social well-being, participation in organized sports also seems to promote adolescents’ brain health. Screen time should be kept within reasonable limits, and it should preferably involve digital media that stimulates activity and movement.”

The studies, conducted as part of the Physical Activity and Nutrition in Children study (PANIC) and the FitBrain study, involved 45 healthy Finnish adolescents aged 16–19, including 25 girls and 20 boys.

Cardiorespiratory fitness was assessed via a direct maximal cycle ergometer test, muscular strength via a standing long jump test, speed and agility via a 10 x 50 meter shuttle run test, and upper limb coordination via a box and block test. Questionnaires were used to evaluate screen time and participation in organized sports, supervised exercise other than sports, and unsupervised physical activity.

Transcranial magnetic stimulation, TMS, was used to measure, e.g., the brain’s response to stimuli induced by a magnetic pulse, and the brain’s ability to inhibit or suppress activity as needed. These measurements reflect excitatory and inhibitory brain function regulated by neurotransmitters such as glutamate and GABA. These same neurotransmitters influence brain plasticity, and their dysregulation is associated with problems with attention, and with mental health disorders.