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CC BY V4.0, Open Access
Journal article
Influence of prior alkalosis or acidosis on physiological responses during passive hyperthermia
Experimental physiology, Early View
2026
PMID: 41757424
Abstract
This study manipulated the blood pH of participants to be mildly acidic or basic prior to passive hyperthermia to examine its effects on thermoregulatory and chemo-regulatory responses, including ventilatory parameters, rectal temperature (Tre) and thermal perception. Twelve healthy males attended three experimental sessions in a double-blind, randomised, counterbalanced design. Passive hyperthermia was induced by hot water immersion at 40°C following the consumption of corn starch (placebo; PLA), ammonium chloride (AC) or sodium bicarbonate (SB). Compared with PLA, SB consumption increased blood pH and HCO3−, whilst AC decreased both blood pH and HCO3− (all P < 0.001). Specifically, minute ventilation was unchanged following SB (11.0 ± 3.7 L min−1) but higher following AC (13.2 ± 5.3 L min−1) compared with PLA (11.9 ± 5.1 L min−1; P = 0.002). Changes in ventilatory equivalent for O2 and CO2 were greater in AC and lower in SB compared with PLA (P < 0.05). Tre increased similarly across all conditions (P = 0.089), whilst immersion times approached a difference (SB: 51.1 ± 10.2 min, AC: 52.9 ± 8.1 min, and PLA: 56.8 ± 6.8 min; P = 0.06). Thermal sensation was higher in AC compared with PLA and SB (all P < 0.001), with no difference between PLA and SB (P = 0.45). Thermal discomfort was not different between AC and SB (P = 0.66), both of which were higher than PLA (all P < 0.001). The magnitude and characteristics of ventilatory response during hyperthermia were influenced by prior alkalemia or acidosis, coinciding with differences in thermal perceptions.
Details
- Title
- Influence of prior alkalosis or acidosis on physiological responses during passive hyperthermia
- Authors/Creators
- Jacky Soo - Murdoch UniversityShernise Ng - National University of SingaporeChris Abbiss - Edith Cowan UniversityOlivier Girard - The University of Western AustraliaMohammed Ihsan - Physical Education Department, College of Education, United Arab Emirates University, Al Ain, United Arab Emirates
- Publication Details
- Experimental physiology, Early View
- Publisher
- John Wiley & Sons Ltd on behalf of The Physiological Society.
- Number of pages
- 11
- Identifiers
- 991005869302607891
- Copyright
- © 2026 The Author(s).
- Murdoch Affiliation
- Murdoch University
- Language
- English
- Resource Type
- Journal article
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