Childhood obesity is an epidemic affecting over 340 million youth worldwide, with rates continuing to increase each year. Importantly, childhood obesity does not occur in isolation, as rates of physical inactivity are also increasing, with children and teens being less physically active now than in the past. These areas of public health are incredibly interrelated, because children with obesity commonly become adults with obesity, and inactive children also tend to become inactive adults. As of 2018, four out of five adolescents, and three out of four adults, did not meet the recommended levels of regular physical activity in the U.S., with $117 billion in annual health care costs related to physical inactivity.
Childhood obesity, which can result from physical inactivity as well as many other lifestyle factors, has been associated with cognitive decline, neurological disorders and mental health issues. However, participation in physical activity can prevent obesity and consequently promote cardiorespiratory fitness, physical health and cognitive and brain function.
In our study published in Medicine & Science in Sports & Exercise®, we investigated the brain-fitness-adiposity relationship in children aged 8-11 years. Using a data-driven approach, we aimed to identify differences among obesity and cardiorespiratory fitness measures on resting state functional brain networks as acquired with functional magnetic resonance imaging (fMRI). The amount of adipose tissue in the body was derived by dual-energy-X-ray absorptiometry (DXA). Cardiorespiratory fitness was derived from VO2max testing. Relative VO2max measures were adjusted for lean body mass.
Our study was novel for two reasons. First, it utilized a data-driven approach to identify which physiological measures were associated with functional regions of the preadolescent brain, from the whole sample of 121 children. Second, our results identified evidence for a brain-fitness-adiposity relationship such that overall, a negative effect of adiposity-related brain patterns and a positive effect of fitness-related brain patterns were observed using a functional network parcellation of the brain. These networks, which have been associated with cognitive functions, have previously been established in association with either fitness or adiposity paradigms. However, the key takeaway from our study is that functional brain networks were found to be differentially associated with positive (e.g., cardiorespiratory fitness) and negative (e.g., obesity) health factors during childhood. Further, mediation analyses revealed that that cardiorespiratory fitness did not mediate the relationship between adiposity and functional brain networks. Additionally, adiposity did not mediate the relationship between cardiorespiratory fitness and functional brain networks. These findings suggest the negative effects of the brain-adiposity relationship and the positive effects of the brain-fitness relationship were independent of each other.
Our study provides novel findings that advance our understanding of the underlying functional brain networks associated with physiological health factors in preadolescent children, which is important for optimal brain health. As childhood obesity is a global health concern, considerable efforts should be taken to reduce the negative health outcomes, such as the negative associations with brain function, associated with childhood obesity. Notably, there are many environmental and health factors associated with the development of childhood obesity. However, targeting the issue of global physical inactivity with the promotion of exercise during childhood is one avenue whereby physiological health, such as cardiorespiratory fitness, can be improved and consequently promote brain health.
Nicole Logan, PhD, is an assistant professor of kinesiology in the University of Rhode Island College of Health Sciences. She has a background in psychology, neuroscience and exercise science, and earned her doctoral degree in psychology from Northeastern University. Dr. Logan’s research investigates how a variety of health factors, such as exercise, cardiorespiratory fitness, childhood obesity, mental health and developmental adversity, influence our cognition and brain function across the lifespan. Originally from New Zealand, she has been an elite international and NCAA water polo coach.
Viewpoints presented in SMB commentaries reflect opinions of the authors and do not necessarily represent ACSM positions or policies. Active Voice authors who have received financial or other considerations from a commercial entity associated with their topic must disclose such relationships at the time they accept an invitation to write for SMB.
