The Effect of 16-Minute Thermal Stress and 2-Minute Cold Water Immersion on the Physiological Parameters of Young Sedentary Men

Abstract

This study aimed to determine the effect of 16 minutes of thermal stress followed by 2 minutes of cold water immersion on the physiological parameters of fifty-five sedentary men (mean age 20.15±1.30 years), who were exposed to 16 minutes of sauna (temperature: 90-91°C; relative humidity: 14-16%) followed by 2 minutes of cold water immersion (12°C). The participants' somatic characteristics were determined before entering the sauna, and their body mass and blood pressure were measured before and after sauna treatment. Physiological parameters were monitored during the 16-minute sauna session and the 2-minute cold water immersion (CRIO) or shower. The subjects perspired 0.21-0.27 litres during the 18-minute session. Heart rate values did not differ significantly between groups during the 16-minute sauna session, but significantly (p<0.001) lower HR values were noted in the CRIO group than in the control group (68.6:105.7 and 57.5:90.7 bpm). The values of SBP and DBP did not differ significantly between groups before the sauna but were significantly (p<0.001) lower in the CRIO group after sauna (SBP – 122.0:127.3 mmHg, DBP – 89.9:76.3 mmHg). In both groups, the participants remained within the easy effort range during most of the 18-minute session (650.9 and 492.6 s). A 16-minute sauna session followed by 2 minutes of cold water immersion induces a significantly greater decrease in HR and BP (SBP and DBP) than a 16-minute sauna session followed by 30 seconds in the shower and a 90 s resting period. During cold water immersion, HR values often decrease to the bradycardia range. Heart rate increased steadily in both groups.