The effect of chronotype and circadian variation on physical performances in football : do we have the right tools?

Abstract

Circadian rhythms, the near 24 hour oscillations involved in the regulation of a vast number of physiological processes, have been recognised to have an effect on physical performance. This effect is characterised by an evening peak in short-term, maximal performances. Inter-individual variations in circadian rhythms have also been identified and are referred to as chronotypes. Often subjectively assessed on a scale of morningness-eveningness, individuals' chronotypes are based on the time of the natural preference for sleep, arising, as well as the performance of physically and mentally engaging tasks. The primary method of chronotype identification is through the Morningness-Eveningness Questionnaire (MEQ), developed in 1976 and validated through the circadian rhythm of oral temperature. While the effect of chronotype on physical performances and dose-responses to these have previously been examined, evidence is conflicting and limited by the predominate use of general populations and individual components of physical performance. The primary aim of this thesis was to assess the effect of chronotype on elite, team sport athletes' physical performance metrics (Study 1, Chapter 3) as well as pre-training wellness and dose-response to field based training (Study 3, Chapter 5). In order to accurately ascertain this, it became apparent that the development and validation of an athlete specific chronotype index was necessary (Study 2, Chapter 4). The current methodology used to chronotype individuals may not be appropriate for an athlete population. This will be the first body of research, to the author's knowledge, to produce and validate an athlete specific chronotype index. The series of investigations to be performed in this thesis will be the first to examine the effects of chronotype upon physical performance metrics in team sports, as well as the first to implement a new and valid chronotype tool to observe the effect of chronotype upon the dose-response to physical performance.

Date of Award	2021
Original language	English