New insights into the understanding of exercise tolerance and regulation
: a place for cardiac interoception

  • Jake B. Butterworth

Student thesis: Doctoral Thesis


Perception of physiological states, termed interoception, is proposed to influence the regulation of exercise intensity including decisions associated with pacing and task ending. Importantly, individuals are known to differ in their accuracy and awareness of interoceptive signals at rest. However, the potential influence of these differences on exercise regulation and tolerance remains poorly understood. Moreover, individual differences in sensitivity to interoceptive signals may be partially influenced by a person’s physiological characteristics such as resting heart rate, which may be modified following prolonged exercise engagement. This thesis aimed to examine the influence of interoception on exercise regulation and tolerance.

Study 1 examined the influence of aerobic fitness parameters on cardiac interoception. Greater accuracy in heartbeat perception corresponded with significantly greater aerobic fitness. Partial correlations supported this finding, indicating significant positive relationships between markers of aerobic fitness (power output (PO) and oxygen consumption at ventilatory thresholds and peak) with heartbeat perception accuracy and awareness when controlling for age, gender, and body composition, but not resting heart rate. Extending on these findings, Study 2 examined the influence of a 4-week exercise intervention on aerobic fitness and interoception. The exercise intervention did not significantly influence changes in either aerobic fitness or interoceptive abilities. These null effects indicated that repeated exposure to augmented interoceptive feedback alone was not sufficient to alter a person’s interoceptive abilities. In Study 3, the influence of interoception on time-to-task failure (TTF) in a constant-load exercise task (80% POpeak) was examined. Interoceptive accuracy did not significantly influence TTF. Furthermore, physiological responses and ratings of perceived exertion (RPE) were not significantly different between good and poor heartbeat perceivers, suggesting that interoceptive accuracy did not affect exercise tolerance. Finally, Study 4 examined the regulation of exercise work rates at perceived light (RPE10 on the Borg 6-20 scale) and hard-to-very hard (RPE16) efforts between good and poor heartbeat perceivers. Good perceivers exhibited greater changes in PO between conditions compared with poor perceivers with differing pacing strategies evident between groups over the first 5-minutes of both conditions. Additionally, good perceivers experienced lower physiological strain (i.e., heart rate and respiratory exchange ratio) in RPE10 but not RPE16, suggesting that interoception may influence sensitivity to allostatic demand at low intensities.

In conclusion, these findings suggest that interoception is influenced by adaptations associated with aerobic fitness but is not modifiable following short-term exercise interventions. Moreover, differences in interoceptive accuracy may influence the regulation of self-paced exercise but do not affect exercise tolerance under constant load.
Date of AwardJan 2021
Original languageEnglish
Awarding Institution
  • University of Brighton
SupervisorJeanne Dekerle (Supervisor), Nicholas Smeeton (Supervisor) & Hugo Critchley (Supervisor)

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