Reliability and face validity of a protocol for defining the inflection point in deep body temperature during cycling exercise in a high and low humidity

Ella Walker, Jo Corbett, James R. House, Mike Tipton

Research output: Contribution to conferenceAbstractpeer-review

Abstract

Reliability is an essential criteria if a test is to be considered valid. However, the reliability of critical environmental limits, have not been established. These limits are defined as where an ambient thermal burden is progressively incremented causing a point where deep body temperature increases without returning to stability, indicating that the conditions for thermal balance are no longer satisfied because of excessive dry heat gain or insufficient evaporative heat loss. Two studies were conducted to: i) determine the reliability of the deep body temperature (Tre) inflection point under conditions of low- and high-humidity (LH and HH); ii) to establish whether the Tre inflection point determined with an continuous type protocol provides a valid index of the transition from a compensable (CO) to uncompensable (UN) thermal environment.

Study 1 method: n=8 healthy males completed two tests commencing at 34 °C, 20 % RH (LH) and two commencing at 28 °C, 80 % RH (HH) at 60 W. There were two phases in each trial: a) CO phase - 60 minutes at 60 W; b) UN phase – immediately following the CO phase, ambient temperature (Tdb) was increased by 1 °C every 5 minutes, UN was confirmed by an inflection in Tre (Treinfl). Study 2 method: n=9 healthy males completed two visits at 34 °C, 20 % RH at 60 W. Visit 1) protocol: as above in Study 1 and Visit 2) protocol: Tdb was raised as per Study 1, but then held at a Tdb just beyond the Treinfl point in Visit 1).

Study 1 showed that Treinfl was identified successfully using the Dmax method (used by previous authors) with low CV (<10%), had good face validity, and was less subjective than a purely visual approach. Study 2 showed that when Tdb was clamped in Visit 2, Tre continued to increase for a further 40 -60 minutes.

Thus, it appears that the protocol is reliable in causing a Treinfl (Study 1) and that participants had achieved an uncompensable thermal state when the Treinfl occurred (Study 2). Therefore, previous authors were correct to conclude that their protocols provide insight into thermal and non-thermal factors which affect the point of uncompensability in adults and children.
Original languageEnglish
Pages196
Number of pages1
Publication statusPublished - 1 Nov 2017
EventThe 17th International Conference on Environmental Ergonomics (ICEE 2017, Kobe) - Kobe, Japan
Duration: 12 Nov 201717 Nov 2017

Conference

ConferenceThe 17th International Conference on Environmental Ergonomics (ICEE 2017, Kobe)
Country/TerritoryJapan
CityKobe
Period12/11/1717/11/17

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