Exercise has been shown to have positive effects on the brain and behavior throughout various stages of the lifespan. However, little is known about the impact of exercise on neurodevelopment during the adolescent years, particularly with regard to white matter microstructure, as assessed by diffusion tensor imaging (DTI). Both tract-based spatial statistics (TBSS) and tractography-based along-tract statistics were utilized to examine the relationship between white matter microstructure and aerobic exercise in adolescent males, ages 15-18. Furthermore, we examined the data by both (1) grouping individuals based on aerobic fitness self-reports (high fit (HF) vs. low fit (LF)), and (2) using VO2 peak as a continuous variable across the entire sample. Results showed that HF youth had an overall higher number of streamline counts compared to LF peers, which was driven by group differences in corticospinal tract (CST) and anterior corpus callosum (Fminor). In addition, VO2 peak was negatively related to FA in the left CST. Together, these results suggest that aerobic fitness relates to white matter connectivity and microstructure in tracts carrying frontal and motor fibers during adolescence. Furthermore, the current study highlights the importance of considering the environmental factor of aerobic exercise when examining adolescent brain development.
Keywords: AD; AF; ATR; Adolescence; Aerobic exercise; BMI; CST; DTI; DWI; Diffusion tensor imaging; FA; FACT; FDR; FMRIB Software Library; FSL; Fmajor; Fminor; HF; IFO; ILF; IQ; L; LF; LME; M; MNI; Montreal Neurological Institute; PDS; PLQ; Personal Lifestyle Questionnaire; Pubertal Development Scale; R; RD; ROI; SE; SES; TE; TI; TR; Tractography; UNC; VO(2) peak; White matter; YAAQ; Youth Adolescent Activity Questionnaire; anterior thalamic radiations; arcuate fasciculus; axial diffusion; body mass index; corticospinal tract; diffusion tensor imaging; diffusion-weighted images; echo time; false discovery rate; fiber assignment by continuous tracking; forceps major; forceps minor; fractional anisotropy; general intelligence; high-fit; inferior fronto-occipital fasciculus; inferior longitudinal fasciculus; inversion time; left; linear mixed-effects; low-fit; mean; peak aerobic uptake; radial diffusion; region of interest; repetition time; right; socioeconomic status; standard error; uncinate fasciculus.
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