FMRI Asessed Neural Activation in Blood Flow Restricted Handgrip Exercise

Abstract

PURPOSE: Blood-flow-restricted (BFR) exercise is reported to improve strength and elicit muscle hypertrophy, although little is known about its neural effects. The purpose of this study was to investigate brain neural responses to BFR exercise and control conditions during handgrip exercise. METHODS: Twenty-five subjects completed dynamic handgrip exercises during BFR and control conditions on two different days separated by 72 hours. fMRI scans were acquired during both exercise conditions. The exercise protocol consisted of five 30-second sets of squeezing a non-metallic handgrip exerciser (a reported 13.6 kg resistance), doing as many repetitions as possible, with 20-second rest intervals between sets. RESULTS: There was a significant main effect of exercise condition in the neural activity in the premotor dorsal (F = 5.71, p = 0.022), premotor ventral (F = 8.21, p = 0.007), and right ventral striatum (F = 7.36, p = 0.01) areas. When considering anatomical regions of interest, we found no significant differences between exercise conditions in the bilateral primary sensory cortex (p = 0.82), primary motor cortex (p = 0.33), supplementary motor area (p = 0.66), cerebellum (p = 0.70), insular cortex (p = 0.45), anterior cingulate cortex (p = 0.24), or thalamus (p = 0.66). Significant linear trends (p = 0.001) over the five exercise sets were found in the bilateral anterior cingulate cortex, right middle frontal gyrus, and the right primary sensory cortex. The right primary sensory cortex, left primary sensory cortex, and the right anterior cingulate cortex showed a main effect of set (p = 0.02). CONCLUSIONS: Less total work was completed during BFR exercise with similar brain neural activation as a higher volume control exercise. BFR exercise has direct effects on the central nervous system.