Abstract

The brain plays a central role in the control of a pacing strategy, yet the brain has a limited information processing capacity and energy supply (Harris et al. Neuron 2012;75:762–77). This study is the first to evaluate the impact of increasing the already required cognitive demands of self-pacing (Suzuki et al. NeuroImage 2004;23:1020–26) on 5 km running performance. Eleven participants (24±4 y; 178±6 cm; 75.0±7.2 kg; 53.1±2.7 ml·kg·min⁻¹) ran, in a randomised order and on separate days, three 5 km trials on a self-paced treadmill. This included i) a baseline trial (CON), ii) a trial during a continuous Wisconsin Card Sorting Task (WCST_5 km) and iii), a trial during a continuous Simplified Go/No-Go Task (SGNG_5 km). Electromyographic measures (EMG) of the Vastus Lateralis, task effort awareness (TEA), physical-ratings of perceived exertion (P-RPE) and feeling scale (FS) were obtained every 0.5 km. Finishing times from CON (1706±273 s) to SGNG_5 km (1750±282 s) were not significantly increased (p=0.18), yet an increase was found from CON to WCST_5 km (1783±293 s; p<0.01). EMG was reduced from CON to SGNG_5 km (p<0.01) and from CON to WCST_5 km (p<0.01). P-RPE was reduced from CON to WCST_5 km (p=0.049) and from SGNG_5 km to WCST_5 km (p<0.01). TEA was reduced from CON to SGNG_5 km (p=0.03) and WCST_5 km (p<0.01). FS during WCST_5 km was increased against CON (p<0.01) and SGNG_5 km (p=0.04). Percentage correct responses were not significantly reduced during SGNG_5 km against a baseline SGNG (p=0.06), yet a reduction was found during WCST_5 km against a baseline WCST (p<0.01). Increased cognitive load negatively affects pacing of a 5 km run suggesting a ‘draining’ effect occurs during the task. Brain areas associated with the WCST (prefrontal regions) may have a role in the implementation of pace regulation during self-paced running. This study provides a novel approach for future research investigating the role of the brain during endurance exercise performance.