Table 2. Exercise characteristics and fluid balance parameters at baseline and after day 1 and day 3
BaselineDay 1Day 3P‐value
Exercise characteristics
Exercise duration (hh:mm)8:10 ± 1:598:28 ± 1:530.29
Average HR (bpm)112 ± 14
Exercise intensity (% of HR max)70.8 ± 8.9
Walking speed (km/h)4.8 ± 0.74.7 ± 0.70.22
WBGT (°C)21.1 ± 1.517.6 ± 2.5b <0.001
Relative humidity (%)71.4 ± 14.967.5 ± 19.60.08
Fluid balance
Fluid intake (mL/h)309 ± 121300 ± 1330.48
Water (%)50.7 ± 22.248.1 ± 21.00.26
Other (%)49.3 ± 22.251.9 ± 21.00.26
Urine osmolality (mOsm/mL)c890 (589–1113)998 (719–1159)945 (649–1264)0.36
Hemoglobin (mmol/L)15.2 ± 1.415.5 ± 1.5a14.8 ± 1.5a, b <0.001
Hematocrit (L/L)44.8 ± 4.245.6 ± 4.4a43.5 ± 4.5a, b <0.001
Plasma volume change (%)–2.9 ± 8.55.8 ± 10.7b <0.001
Plasma sodium (mmol/L)141.2 ± 1.6143.4 ± 2.4a141.4 ± 2.0b <0.001
Prevalence of hyponatremia (n(%))0 (0%)0 (0%)0 (0%)1.00
Prevalence of hypernatremia (n(%))1 (1.7%)18 (30%)a2 (3.3%)b <0.001
Body mass change (kg)−0.8 ± 1.0−0.4 ± 0.5b 0.001
Body mass change (%)−0.9 ± 1.2–0.4 ± 0.7b 0.005
Dehydration; ≥2% body mass loss (n(%))12 (20%)0 (0%)b <0.001
Inflammation
Plasma IL‐6 (pg/mL)0.5 (0.3–0.6)5.2 (3.4–8.4)a2.0 (1.5–3.5)a, b<0.001
TNF‐α (pg/mL)1.53 (1.3–1.8)1.6 (1.4–1.9)a1.5 (1.3–1.7)a, b<0.001
  • Exercise characteristics and fluid balance at baseline, after exercise day 1 and day 3. Data were presented as mean ± SD or median (IQR). P‐values represents the results of the one‐way ANOVA or nonparametric alternative.

  • a Significantly different from baseline.

  • b Significantly different from day 1.

  • c A nonparametric alternative was used: Friedman test for time‐effect and Wilcoxon signed‐ranks test for differences between individual days.