Post-Shower Cardiovascular and Oxygenation Responses During an Antarctic Inland Traverse: A Single-Participant Repeated-Measures Study

Introduction Polar field hygiene may require transitions between severe cold, warm-water exposure, and sheltered recovery. Physiological responses to this sequence are poorly described. Methods A healthy 35-year-old man completed 13 approximately 5-min showers using approximately 10 L of water at 40 °C late in a 78-day inland Antarctic traverse. Systolic and diastolic blood pressure, heart rate, and peripheral oxygen saturation (SpO 2 ) were measured after 20 min of seated rest before showering, at the first post-shower measurement obtained within 5 min of shower completion, and every 5 min thereafter for 60 min. Analyses included exploratory Friedman tests, Holm-adjusted Wilcoxon signed-rank comparisons with baseline, and Spearman correlations with barometric pressure and outdoor temperature. Results Mean (SD) altitude was 3042.8 (707.5) m, barometric pressure 668.9 (59.8) hPa, and outdoor temperature −25.8 (5.1) °C. Mean systolic/diastolic blood pressure was 122.5/83.8 mm Hg at baseline, 127.2/87.4 at the first post-shower measurement, and 118.9/81.3 at 60 min. Mean heart rate was 90.6, 88.0, and 78.8 beats/min, respectively. Mean SpO 2 was 90.9%, 91.2%, and 90.9%. Temporal variation was detected only for heart rate ( P < .001); after Holm adjustment, heart rate was lower than baseline from 10 through 60 min. No environmental correlation remained significant after Holm adjustment. Conclusions During measured post-shower recovery, blood pressure showed no sustained elevation and SpO 2 no sustained decline, whereas heart rate decreased during seated recovery. Changes during showering and transfer were not captured; these observations do not establish safety.