M3 blood pressure monitor

The average of three blood pressure readings using an Omron M3 blood pressure monitor and an Omron cuff (32–42 cm) while at rest at one-minute intervals was used.
CRF, an index of metabolic and cardiovascular profile, was assessed using the 3 min Step Test [24 (link)] which has been found to strongly correlate with VO₂max and have excellent discriminative validity in a pediatric population [25 (link)]. Participants step up and down on a 30.5 cm step at an established rhythm set of 24 steps per minute using a digital metronome KORG Micrometro. Heart rates (HR) are monitored prior to the test, during the 3 min of exercise load (step-test), immediately after, and one minute post [24 (link)] using the electronic analyzer, TM 100 Pro Tech Med Heart Rate Monitor. Post-effort HR values were analyzed and recorded for one minute. Scores were automatically generated based on the arithmetic mean of HR following Jacks et al. formula [26 (link)] to categorize CRF as very poor, poor, satisfactory, good, very good, or excellent.

Orthostatic hypotension was measured and defined according to clinical guidelines (Freeman et al., 2011 (link)) as a reduction of ≥20 mmHg in systolic blood pressure (SBP) or ≥10 mmHg in diastolic blood pressure (DBP) when compared with values obtained at baseline, before the immersion period. Seated blood pressure was recorded using an automated sphygmomanometer (M3 blood pressure monitor; Omron, Kyoto, Japan) whilst seated on a chair or during the final 5 min of immersion. Baseline blood pressure was recorded in triplicate at the start of the protocol following a 5 min period of quiet rest. Participants were instructed to stand up gradually upon the sensation of cuff inflation, with a single measure of standing blood pressure taken. Upon standing, participants reported symptoms of dizziness on the same 0–10 scale used for indices of heat illness (Coris et al., 2006 (link)), with standing dizziness being recorded as the maximum dizziness reported. Owing to the transient nature of standing dizziness, participants reporting scores ranging from 7 to 10 were given the option to continue if their symptoms had subsided by the time they had to re‐enter the water.