Differential Effects of Blood-Flow Restriction and High-Intensity Resistance Training on Cortical Thickness and White Matter Integrity in Older Men: A Three-Group Randomized Controlled Trial.

Objectives: While longitudinal studies have linked parietal lobe structure and muscle mass, no resistance exercise studies have evaluated whether interventions can have a positive impact on parietal lobe structure. Therefore, we investigated the effects of high-intensity resistance training (HIRT) and blood-flow restriction training (BFRT) on cortical thickness and white matter integrity in the parietal region, as well as in other regions, in an exploratory manner. Methods: A total of 63 older men were assigned to BFRT, HIRT or control groups for 12 weeks of intervention. A total of 48 participants completed brain and thigh magnetic resonance imaging before and after intervention. Cortical thickness was assessed using FreeSurfer, fractional anisotropy (FA) values were calculated using ExploreDTI, thigh muscle anatomical cross-sectional area was measured from MRI. Results: A significant difference in cortical thickness was observed only in HIRT group in the left parietal cortex-inferior parietal, supramarginal and posterior cingulate. Exploratory analyses revealed cortical thickness changes in other left-hemisphere regions, including the temporal (bankssts, inferior temporal), frontal (medial orbitofrontal, precentral, rostral middle frontal), and occipital (lateral occipital) cortices. In contrast, the BFRT group showed significant FA value change in parietal region - in left inferior parietal, left precuneus and right superior parietal. Exploratory analyses showed FA value change in additional regions in the BFRT group, including the left frontal (caudal middle frontal and superior frontal), left temporal (fusiform), right occipital (lateral occipital), and in the HIRT group, in the left frontal region (pars opercularis). Conclusions: HIRT and BFRT were associated with beneficial brain structural changes, although through distinct neurobiological mechanisms, with HIRT primarily influencing cortical thickness and BFRT predominantly affecting white matter microstructure.