Abstract
PurposeHypercapnic chemosensitivity traditionally captures the ventilatory response to elevated pressures of carbon dioxide in the blood. However, hypercapnia also contributes to subjective breathing perceptions, and previously we demonstrated a closer matching of perception to changes in ventilation in athletes compared to controls. Here we investigated any potential underlying hypercapnic chemosensitivity differences between groups, and explored whether these measures relate to ventilatory and perceptual responses during exercise as well as trait levels of affect.MethodsA hypercapnic challenge, incremental maximal exercise test and affective questionnaires were completed by 20 endurance athletes and 20 age-/sex-matched sedentary controls. The hypercapnic challenge involved elevating end-tidal PCO2 by 0.8% (6.1 mmHg) and 1.5% (11.2 mmHg) for 3 min each (randomised), with constant end-tidal oxygen. Ventilatory and perceptual responses to hypercapnia were compared between groups, and within each group the relationships between hypercapnic chemosensitivity (slope analyses) and exercising ventilation and perceptions were calculated using Spearman’s non-parametric correlations.ResultsWhile absolute ventilation differences during hypercapnia and exercise were observed, no group differences were found across hypercapnic chemosensitivity (slope) measures. Correlation analyses revealed the anxiety hypercapnic response was related to maximal exercise anxiety, but only in sedentary individuals.ConclusionVentilatory and perceptual hypercapnic chemosensitivity do not differ between athletes and sedentary individuals. However, ventilatory and anxiety hypercapnic chemosensitivities were related to ventilatory and anxiety responses during exercise in untrained individuals only. Athletes may employ additional strategies during exercise to reduce the influence of chemosensitivity on ventilatory and perceptual responses.
Highlights
Hypercapnia occurs when there is elevated pressure of carbon dioxide in the blood (PCO2)
Increased ventilation due to hypercapnia does not directly translate to increased perceptions of breathlessness and anxiety (Banzett et al, 1990; Li et al, 2006), and previously we demonstrated a stronger relationship between hypercapnia-induced changes in ventilation and breathing perceptions in athletes compared to sedentary controls at rest (Faull et al, 2016)
This raises the question as to whether there is an inherent difference in hypercapnic chemosensitivity in the ventilatory and/or perceptual domains in athletes, and how these responses at rest may translate to differences in ventilation and perceptions during exercise
Summary
Hypercapnia occurs when there is elevated pressure of carbon dioxide in the blood (PCO2). Increased ventilation due to hypercapnia does not directly translate to increased perceptions of breathlessness and anxiety (Banzett et al, 1990; Li et al, 2006), and previously we demonstrated a stronger relationship between hypercapnia-induced changes in ventilation and breathing perceptions (breathlessness and anxiety) in athletes compared to sedentary controls at rest (Faull et al, 2016). This raises the question as to whether there is an inherent difference in hypercapnic chemosensitivity in the ventilatory and/or perceptual domains in athletes, and how these responses at rest may translate to differences in ventilation and perceptions during exercise. Understanding these relationships will help shed light on the contribution of baseline ventilatory and perceptual hypercapnic chemosensitivities to our responses during incremental exercise
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