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Assessment of salivary cortisol dynamics in an infantry training exercise: a pilot study.
- Source :
-
BMJ military health [BMJ Mil Health] 2024 Apr 11. Date of Electronic Publication: 2024 Apr 11. - Publication Year :
- 2024
- Publisher :
- Ahead of Print
-
Abstract
- Introduction: Measuring cortisol during military training offers insights into physiological responses to stress. We attempted precisely timed, cortisol awakening response (CAR) and pre-sleep cortisol (PSC), and diurnal slope (peak morning minus evening cortisol), during a British Army exercise. We aimed to understand cortisol dynamics and evaluate the feasibility of CAR and PSC in this environment.<br />Method: Setting: high-intensity, 10-day infantry exercise. Participants: regular infantry soldiers exercising (EX, n=25) or headquarters-based (HQ, n=6). Participants undertook PSC and WAKE and WAKE+30 min samples after 1-2 days, 5-6 days and 9-10 days. Wrist-worn GENEActiv accelerometers were used to assess sleep duration in EX only. Samples taken ±15 min from prespecified time points were deemed adherent. Validated questionnaires were used to measure resilience and perceived stress. Cortisol and cortisone were measured simultaneously by liquid chromatography tandem mass spectrometry.<br />Results: From adherent participants' samples, CAR was positive and tended to decrease as the exercise progressed. From all available data, HQ demonstrated greater diurnal slope than EX (F=7.68, p=0.02), reflecting higher morning cortisol (F=4.72, p=0.038) and lower PSC (p=0.04). No differences were seen in cortisol:cortisone ratio. 26.1% of CAR samples were adherent, with moderately strong associations between adherence and stress (r=0.41, p=0.009) but no association between adherence and day of exercise (χ <superscript>2</superscript> =0.27, p=0.8), sleep duration (r=-0.112, p=0.43) or resilience (r=-0.79, p=0.75). Test-retest reliability ratings for CAR were Cronbach's α of 0.48, -11.7 and 0.34 for the beginning, middle and end of the exercise, respectively.<br />Conclusions: We observed a reduction in morning cortisol and decreased diurnal slope during a high-intensity military exercise, compared with the HQ comparator cohort in whom diurnal slope was preserved. A carefully timed CAR was not feasible in this setting.<br />Competing Interests: Competing interests: None declared.<br /> (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)
Details
- Language :
- English
- ISSN :
- 2633-3775
- Database :
- MEDLINE
- Journal :
- BMJ military health
- Publication Type :
- Academic Journal
- Accession number :
- 38604756
- Full Text :
- https://doi.org/10.1136/military-2023-002622