Cognitive activity and cerebral oxygenation during a 20-km cycling time trial

Introduction Maintenance of cerebral oxygenation (O2Hb) within a stable range during endurance exercise is thought to contribute to successful performance (Nielsen & Seifert, 2011). This may be due to the importance of cognitive processes inherent within the ability to regulate pace (Renfree et al., 2013). Yet cognitive function has been suggested to be impaired during high intensity exercise (Dietrich & Audiffren, 2011). Using a dual-task paradigm this study explored the phenomenon of pacing through evaluating the impact of increased cognitive load at different stages of a cycling time trial (TT) on cerebral O2Hb, pacing and time to completion. Methods Twelve well-trained cyclists (31 ± 9 yrs, PPO 352 ± 29 W, VO2peak 57 ± 6 ml⋅kg⋅min-1) performed, in a randomised order, 4 simulated 20-km cycling TTs on separate occasions. These included a control simulated 20- km TT (TTCON) and 3 experimental conditions in which participants concurrently performed an executive cognitive task for the duration of the 1st half (TT1stHCL), the 2nd half (TT2ndHCL) and the whole duration of the TT (TTFullCL). Cerebral O2Hb was assessed at the dorsolateral prefrontal cortex (dLPFC). Blood lactate (BLa), effort (TEA), exertion (P-RPE) and affect (FS) were measured. Results Completion time during TTCON (2122s ±378) compared to all experimental conditions was significantly faster; TT1stHCL (2257s ±382; p<0.01, partial η2=0.93); TT2ndHCL (2205s ±407; p<0.01, partial η2 =0.64); TTFullCL (2307s ±411; p