Introduction: Heat acclimation (HA) reduces the thermoregulatory stress and consequently delays the risk of heat illness during heat stress. Evidence suggests heat shock proteins (HSPs) are contributors to heat adaptation at a physiological and cellular level and are key markers of thermotolerance. Specifically, Hsp72 and Hsp90α have been used as markers of the cellular response to stress The aim of this study was to explore the effect of short-term heat acclimation (STHA) on leukocyte Hsp72 and Hsp90α mRNA response in the elderly population compared with young individuals. Method: Nine, active younger (Y) individuals (Mean [SD]; age 22.2 [1.9] years; height 177 [0.05] cm; mass 75.4 [11.47] kg; 1 female) and six, active older (O) individuals (age 66.7 [2.6] years; height 178 [0.07] cm; body mass 76.8 [9.55] kg; 6 males) completed five consecutive days of HA in 35°C/50% R.H. The STHA protocol increased resting rectal temperature (Tre) by 1.5°C or to 38.5°C within the first 60mins and subsequently maintained Tre for a further 60mins. Leukocyte Hsp72 and Hsp90α mRNA responses assessed using reverse transcription polymerase chain reaction (RT-QPCR) were determined within and between the first and final day of HA, with comparisons made between groups using ANOVA. Results: Resting Tre and heart rate (HR) showed no improvements after STHA in the O group (+0.20±0.21°C, 1±9 b.min-1) but did so in the Y group (-0.21±0.29°C, -6±10 b.min-1). Thermal sensation decreased in O (-0.3±0.4) and Y (-0.3±0.4) with a significant change only in Y (p<0.05). Thermal comfort did not change in the O group (0±1) but decreased in the Y group (1±1). Changes in Hsp72 and Hsp90α mRNA transcription in response to each session in the older and younger group is currently being analysed. Conclusions: STHA appears less effective in active older individuals compared younger participants given reduced phenotypic adaptation.
|Publication status||Published - 2019|