Which indices of cardiorespiratory fitness are more strongly associated with brain health in children with overweight/obesity?

PURPOSE: To compare the strength of associations between different indices of cardiorespiratory fitness (CRF) and brain health outcomes in children with overweight/obesity. METHODS: Participants were 100 children aged 8-11 years. CRF was assessed using treadmill exercise test (peak oxygen uptake [V̇O2peak ], treadmill time, and V̇O2 at ventilatory threshold) and 20-metre shuttle run test (20mSRT, laps, running speed, estimated V̇O2peak using the equations by Léger et al., Mahar et al., and Matsuzaka et al.). Intelligence, executive functions, and academic performance were assessed using validated methods. Total gray matter and hippocampal volumes were assessed using structural MRI. RESULTS: V̇O2peak /body mass (β = 0.18, 95% CI = 0.01-0.35) and treadmill time (β = 0.18-0.21, 95% CI = 0.01-0.39) were positively associated with gray matter volume. 20mSRT laps were positively associated with executive functions (β = 0.255, 95% CI = 0.089-0.421) and academic performance (β = 0.199-0.255, 95% CI = 0.006-0.421), and the running speed was positively associated with executive functions (β = 0.203, 95% CI = 0.039-0.367). Estimated V̇O2peak/Léger et al. was positively associated with intelligence, executive functions, academic performance, and gray matter volume (β = 0.205-0.282, 95% CI = 0.013-0.500). Estimated V̇O2peak/Mahar et al. and V̇O2peak/Matsuzaka et al. (speed) were positively associated with executive functions (β = 0.204-0.256, 95% CI = 0.031-0.436). CONCLUSION: Although V̇O2peak is considered the gold standard indicator of CRF in children, peak performance (laps or running speed) and estimated V̇O2peak/Léger et al. derived from 20mSRT had stronger and more consistent associations with brain health outcomes than other indices of CRF in children with overweight/obesity.