Publication
Impact of military training stress on hormone response and recovery
Publisher:
Public Library of Science (PLoS)
Date:
10-03-2022
DOI:
10.1371/JOURNAL.PONE.0265121
Abstract: Military personnel are required to train and operate in challenging multi-stressor environments, which can affect hormonal levels, and subsequently compromise performance and recovery. The aims of this project were to 1) assess the impact of an eight-day military training exercise on salivary cortisol and testosterone, 2) track the recovery of these hormones during a period of reduced training. This was a prospective study whereby 30 soldiers (n = 27 men, n = 3 women) undergoing the Australian Army combat engineer ‘Initial Employment Training’ course were recruited and tracked over a 16-day study period which included an eight-day military training exercise. Non-stimulated saliva s les were collected at waking, 30 min post waking, and bedtime on days 1, 5, 9, 13, 15 measures of subjective load were collected on the same days. Sleep was measured continuously via actigraphy, across four sequential study periods 1) baseline (PRE: days 1–4), 2) field training with total sleep deprivation (EX-FIELD: days 5–8), 3) training at simulated base c with sleep restriction (EX-BASE: days 9–12), and 4) a three-day recovery period (REC: days 13–15). Morning cortisol concentrations were lower following EX-FIELD (p .05) compared to the end of REC. Training in the field diminished testosterone concentrations (p .05), but levels recovered within four days. Bedtime testosterone/cortisol ratios decreased following EX-FIELD and did not return to pre-training levels. The sensitivity of testosterone levels and the testosterone/cortisol ratio to the period of field training suggests they may be useful indicators of a soldier’s state of physiological strain, or capacity, however inter-in idual differences in response to a multi-stressor environment need to be considered.