Heart rate variability and cognitive performance in response to physical and mental stress

Abstract

It is now well established that physiological and psychological stress affects autonomic function with prolonged bouts of physical and mental stress resulting in negative impacts on health, well-being and quality of life. Heart rate variability (HRV) reflects the continuous interplay between sympathetic and parasympathetic influence on heart rate and is a marker of autonomic function. Heart rate variability has become a popular measure of acute stressors such as exercise and cognitive performance tests. The aim of this thesis was to measure HRV response to acute bout of physiological (heat and exercise) and psychological (cognitive performance tasks) stressors known to affect autonomic function. Study 1 (Chapter 4) demonstrated that HRV is sensitive to alterations in ANS activation during heated water immersion (42 oC), furthermore, HRV is a repeatable measure with no significant difference between two separate exposures in any time, frequency and non-linear domain measures (P >0.05). Study 2 (Chapter 5) identified that while performing the AX-continuous performance task resulted in increased fatigue, as measured by the BRUMS scale, HRV was not sensitive to these changes. Study 3 (Chapter 6) found that HRV was sensitive to physiological stress imposed by exercise and heat (40oC, 55%), with exercise and heat combined causing larger changes in HRV measures (P <0.05) than just exercise and heat alone. The findings from Studies 1 and 3 suggest that HRV is a repeatable measure of physiological stress which is sensitive to the degree of stress. The lack of change in HRV during Study 2 could be due to the AX-CPT not being sufficiently strenuous to cause ANS activation, or that HRV was not sensitive to ANS changes during mentally demanding tasks.

Date of Award	2017
Original language	English
Awarding Institution	Aberystwyth University
Supervisor	Rhys Thatcher (Supervisor)