The complex associations between adiposity, fitness, mental wellbeing and neurocognitive function after exercise: A randomized crossover trial in preadolescent children.

The aim of the present study was to examine the associations of adiposity and fitness on the preadolescent brain's response to acute exercise. In a sample of 58 children (ages 8-10; 19 females), demographic measures of age, sex, IQ, puberty, and socioeconomic status were considered. Children participated in a randomized crossover study, whereby they completed two different interventions; seated rest or treadmill walking, counterbalanced across participants. Associations between adiposity measures (standardized body mass index [BMI-Z], whole body percent fat [%Fat], visceral adipose tissue [VAT]), cardiorespiratory fitness measures (VO₂max and Fat-Free VO₂) were assessed on self-reported measures of mental wellbeing, and cognitive performance (response accuracy, reaction time) and neuroelectric (P3 amplitude and latency) indices of a Go/NoGo task following both exercise and rest interventions. Higher adiposity (whole-body percent fat, BMI-Z) was associated with higher trait anxiety (P's≤0.05) and disordered eating (P's≤0.05) scores. Higher fitness (VO₂max) was associated with lower childhood depression scores (P=0.02). Regression analyses yielded specific post-exercise neurocognitive associations with adiposity-related (VAT, BMI-Z), and fitness-related (FF-VO₂) outcomes, after controlling for post-rest neurocognitive outcomes. VAT was positively associated with post-exercise P3 ERP Latency for the Go task (P≤0.001); BMI-Z was negatively associated with P3 ERP amplitudes for the Go task (P's≤0.005); FF-VO₂ was negatively associated with P3 ERP latency for the Go/NoGo task (P's≤0.05), and positively associated with NoGo task accuracy (P≤0.001). Overall, adiposity and fat-free fitness measures yield sensitive and differential associations with neurocognitive performance after exercise and after rest interventions.