Brain modulation for perceived exertion processing after different cycling exercise intensities: an fmri study

Abstract

Ratings of perceived exertion (RPE) during exercise is processed in the brain, however, the modulation of the associated areas at different intensities levels remains unclear. To verified the brain modulation while RPE processing immediately after cycling exercise performed at different intensities. 24 healthy adults (77.6±9.4 kg; 176±7.2 cm; 25.9±5.9 years old) performed an incremental load test on an adapted cycling ergometer attached to a MRI scanner. The workload started at 25 W and increased 25W after every four blocks of 30 s of cycling and 30 s rest. At the end of each block, participants had four seconds to report their RPE based on the 6-20 Borg scale presented on a screen. The RPE processing periods for RPE responses from 6 to 12 were labeled as LOW intensity while those from 13 to 18 were considered as HIGH intensity. To identify the common areas associated to RPE processing, the one sample t-test was used for each condition (all RPE, LOW and HIGH intensities). The statistical threshold established was family-wise error corrected (FWE<0.05). When grouping all RPE responses throughout exercise intensities, we found an activation of several areas related to motor control (primary motor cortex, primary somatosensory cortex and cerebellum), homeostatic regulation (insular cortex) and cognition for executive functions (dorsolateral and anterior prefrontal cortex), spatial cognition (superior parietal lobule), reflective self-awareness (precuneus), and others (T=5.33; FWE<0.05). For the inhibited areas, we observed brain structures located in occipital lobe, prefrontal cortex, and thalamus, angular gyrus, Wernicke’s area, associative visual cortex, premotor cortex and supplementary motor cortex (T=5.44; FWE<0.05). At LOW, the somatosensory cortex and cerebellum (T=6.46; FWE<0.05) were activated and at HIGH, only the cingulate gyrus was activated (T=6.53; FWE<0.05). By using a gold standard technique to analyze brain activity, we described here the modulation of brain areas to the RPE processing immediately after exercise cessation performed at different intensities. The integration of motor control, homeostatic regulation and cognitive related areas seems to, together, process the RPE responses after exercise