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Prior self-control exertion decreases pre-frontal cortex oxygenation during a CO2 rebreathing challenge but does not affect perceptions of dyspnoea or tolerance time.
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  • James Brown,
  • Ruth Boat,
  • Neil Williams,
  • Michael Johnson,
  • Graham Sharpe
James Brown
Nottingham Trent University

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Ruth Boat
Nottingham Trent University
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Neil Williams
Nottingham Trent University
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Michael Johnson
Nottingham Trent University
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Graham Sharpe
Nottingham Trent University
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Abstract

Introduction: Recently, we showed that males high in trait self-control experience less dyspnoea and persist for longer in a carbon dioxide (CO2) rebreathing challenge than males low in trait self-control. As self-control can also vary within individuals (state self-control), the aim of the present study was to investigate whether prior self-control exertion influenced perceptions of dyspnoea and tolerance to a CO2 rebreathing task in healthy young males. We also used functional near-infrared spectroscopy (fNIRS) to assess haemodynamic activity of the pre-frontal cortex as it is the primary brain region associated with exertion of self-control. Methods: Participants completed a congruent Stroop task (control condition) and an incongruent Stroop task (prior self-control exertion) followed by a CO2 rebreathing challenge until the limit of tolerance. Changes in oxyhaemoglobin (ΔO2Hb) and deoxyhaemoglobin (ΔHHb) from baseline, were assessed continuously in the Stroop task and CO2 rebreathing challenge. Dyspnoea intensity and unpleasantness were rated every 30s. Results: There was no effect of prior self-control exertion on perceptions of dyspnoea or tolerance time in the CO2 rebreathing challenge (all P > 0.05). Average ΔO2Hb from baseline was higher in the difficult Stroop task (prior self-control exertion, 4.25±1.80µM) than the easy Stroop task (control condition, 2.82±1.45µM, P = 0.011). During the subsequent CO2 rebreathing challenge, ΔO2Hb was attenuated following prior self-control exertion.(6.47±2.87µM) compared to the control condition (7.82±2.68µM, P = 0.012). Conclusions: Pre-frontal cortex oxygenation was lower in a subsequent CO2 rebreathing challenge following prior self-control exertion. There was no effect of prior self-control exertion on dyspnoea.