Activation of the insular cortex is affected by the intensity of exercise

The purpose of this investigation was to determine whether there were differences in the magnitude of insular cortex activation across varying intensities of static and dynamic exercise. Eighteen healthy volunteers were studied: eight during two intensities of leg cycling and ten at different time periods during sustained static handgrip at 25% maximal voluntary contraction or postexercise cuff occlusion. Heart rate, blood pressure (BP), perceived exertion, and regional cerebral blood flow (rCBF) distribution data were collected. There were significantly greater increases in insular rCBF during lower (6.3 ± 1.7%; P < 0.05) and higher (13.3 ± 3.8%; P < 0.05) intensity cycling and across time during static handgrip (change from rest for right insula at 2-3 min, 3.8 ± 1.1%, P < 0.05; and at 4-5 min, 8.6 ± 2.8%, P < 0.05). Insular rCBF was decreased during postexercise cuff occlusion (-5.5 ± 1.2%; P < 0.05) with BP sustained at exercise levels. Right insular rCBF data, but not left, were significantly related, with individual BP changes (r² = 0.80; P < 0.001) and with ratings of perceived exertion (r² = 0.79; P < 0.01) during exercise. These results suggest that the magnitude of insular activation varies with the intensity of exercise, which may be further related to the level of perceived effort or central command.