Brain mapping after prolonged cycling and during recovery in the heat

The aim of this study was to determine the effect of prolonged intensive cycling and postexercise recovery in the heat on brain sources of altered brain oscillations. After a max test and familiarization trial, nine trained male subjects (23 +/- 3 yr; maximal oxygen uptake = 62.1 +/- 5.3 ml.min(-1).kg(-1)) performed three experimental trials in the heat (30 degrees C; relative humidity 43.7 +/- 5.6%). Each trial consisted of two exercise tasks separated by 1 h. The first was a 60-min constant-load trial, followed by a 30-min simulated time trial (TT1). The second comprised a 12-min simulated time trial (TT2). After TT1, active recovery (AR), passive rest (PR), or cold water immersion (CWI) was applied for 15 min. Electroencephalography was measured at baseline and during postexercise recovery. Standardized low-resolution brain electromagnetic tomography was applied to accurately pinpoint and localize altered electrical neuronal activity. After CWI, PR and AR subjects completed TT2 in 761 +/- 42, 791 +/- 76, and 794 +/- 62 s, respectively. A prolonged intensive cycling performance in the heat decreased beta activity across the whole brain. Postexercise AR and PR elicited no significant electrocortical differences, whereas CWI induced significantly increased beta 3 activity in Brodmann areas (BA) 13 (posterior margin of insular cortex) and BA 40 (supramarginal gyrus). Self-paced prolonged exercise in the heat seems to decrease beta activity, hence representing decreased arousal. Postexercise CWI increased beta 3 activity at BA 13 and 40, brain areas involved in somatosensory information processing.