Physiological and Perceptual Responses to Heat Acclimatisation and Acclimation in Elite Triathletes

  • Laura Needham

Student thesis: Doctoral Thesis


Tokyo 2020 was predicted to be one of the most thermally challenging games in the history of the modern Olympics; this presented a considerable challenge to endurance events, especially the triathlon (Kakamu et al., 2017). The risk of the environmental conditions (mean wet bulb globe temperature (WBGT) of 33 °C at 09:00 h) meant that there was a significant risk of the triathletes developing exertional heat illness (EHI) and/or a likely reduction in performance (Guy et al., 2015). The British triathletes had a history of inadequate heat preparation for hot and humid races, thus Tokyo posed a significant risk to health and performance. The aim of the research in elite level triathletes (n = 6) was: i) to examine the thermoregulatory responses in races; ii) evaluate heat alleviation strategies (acclimatisation vs. acclimation) employed; iii) critically reflect on changing heat preparation practice.
A within-subject repeated measures research design was adopted, using the individual participants as their own controls. Gastrointestinal temperature (Tgi) was recorded via ingestible capsules in five races. A Standard Heat Exposure (SHE) was designed and implemented to strategically evaluate physiological and perceptual adaptations to acclimatisation and acclimation interventions. For the reflective process, Moon’s (2013) five-stage framework was used.
The thermoregulatory responses were generally characterised by a mean (SD) increase in Tgi of 1.0 (0.2) °C during the swim and 0.5 (0.6) °C on the bike. Followed by an uncompensable increase in Tgi during the run, resulting in a mean peak Tgi of 40.1 (0.6) °C. All elite triathletes’ SHE results pre to post acclimation demonstrated (SD) 5
(2) meaningful changes in the seven key physiological (starting and peak Tgi, exercising and peak heart rate [HR] and sweat rate [SR]) and perceptual (peak thermal stress sensation [TSS] and rating of perceived exertion [RPE]) adaptations when compared to 1 (1) seen with acclimatisation.
The thermoregulatory profiles collected from races facilitated ‘‘buy in’’ from coaches and athletes and helped inform heat preparation e.g., individual peak Tgi for laboratory-based training. Acclimation was shown to be more effective for perceptual and physiological adaptations in elite level triathletes. Although acclimatisation provided opportunities to target behavioural adaptations such as pacing strategies and hydration, that were not possible in the acclimation programme.
For Tokyo 2020, a mixed acclimatisation and acclimation approach that targeted physiological, perceptual, and behavioural adaptations was developed. Critical reflections revealed the practitioner was required to have high levels of contextual knowledge and strong relationships with athletes, coaches, and key stakeholders. The practitioner’s self-awareness regarding their values and behaviours played a critical role in understanding their practice, and how these contributed to changing practice and policy. British triathletes adopted the proposed heat alleviation strategies for Tokyo 2020 and Team GB won three of the seven available triathlon medals: including Olympic Gold in the mixed team relay.
Date of Award20 Feb 2024
Original languageEnglish
Awarding Institution
  • University of Portsmouth
SupervisorMike Tipton (Supervisor), Jo Corbett (Supervisor) & Gemma Milligan (Supervisor)

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