Results of the Tract-based spatial statistics analysis and diffusivity measures for individual swimmers and soccer players. Top: the diffusion tensor for each voxel was estimated by the multivariate linear fitting algorithm, and the tensor matrix was diagonalized to obtain three pairs of eigenvalues and eigenvectors. Voxelwise summary parameters included radial diffusivity and axial diffusivity. Group analyses were performed using whole-brain threshold-free cluster enhancement to obtain significant differences between groups at P < 0.05. After accounting for multiple comparisons using the family-wise error rate, the voxels highlighted in red demonstrate significantly increased radial diffusivity (A) and axial diffusivity (B) values for the soccer group compared with swimmers. Bottom: voxels with a significant group difference as revealed by Tract-based spatial statistics (top) were merged to a single cluster. Circles indicate individual values, squares indicate mean values, and error bars indicate 95% confidence intervals. Diffusivity measures were obtained for each individual and plotted for the two study groups. Linear regression showed no significant association of age or years of training with (A) radial diffusivity (P = 0.13 and P = 0.12, respectively) or (B) for axial diffusivity values (P = 0.22 and P = 0.54, respectively). Used with permission from .