TABLE 2.
Physiological and perceptual measures during heat stress testing before, and after, HEAT acclimation (HEAT) or temperate exercise (CONTROL).
| CONTROL | HEAT | P | |||
|---|---|---|---|---|---|
| Preintervention | Postintervention | Preintervention | Postintervention | ||
| Heart Rate (/min) | |||||
| Resting heart rate | 70 ± 11 | 70 ± 8 | 71 ± 9 | 62 ± 8 | 0.07 |
| Peak heart rate | 166 ± 16 | 168 ± 16 | 165 ± 18 | 152 ± 18 | 0.003 |
| Temperature (°C) | |||||
| Resting temperature (RECTAL) | 37.1 ± 0.2 | 37.1 ± 0.2 | 37.1 ± 0.2 | 36.8 ± 0.3 | 0.006 |
| Peak temperature (rectal) | 38.5 ± 0.3 | 38.6 ± 0.4 | 38.5 ± 0.2 | 38.2 ± 0.3 | 0.01 |
| Mean temperature (rectal) | 37.8 ± 0.2 | 37.9 ± 0.3 | 37.9 ± 0.2 | 37.6 ± 0.2 | 0.0007 |
| Peak temperature (skin) | 36.5 ± 0.5 | 36.6 ± 0.6 | 36.5 ± 0.4 | 36.1 ± 0.3 | 0.03 |
| Mean temperature (Skin) | 35.8 ± 0.6 | 36.1 ± 0.6 | 35.9 ± 0.4 | 35.6 ± 0.4 | 0.006 |
| PSI | |||||
| Peak PSI | 7.3 ± 0.7 | 7.5 ± 1.2 | 7.2 ± 1.2 | 6.3 ± 1.2 | 0.02 |
| Mean PSI | 5.3 ± 0.6 | 5.5 ± 0.8 | 5.4 ± 0.9 | 4.7 ± 0.9 | 0.02 |
| Sweat | |||||
| Sweat loss (L) | 1.82 ± 0.48 | 1.96 ± 0.65 | 1.67 ± 0.36 | 2.05 ± 0.54 | 0.24 |
| Sweat sodium (mg·L−1) | 35.3 ± 12.0 | 42.7 ± 10.8 | 44.1 ± 6.8 | 45.5 ± 5.8 | 0.10 |
| Total nonurinary fluid loss (mL) | 1363 ± 360 | 1476 ± 486 | 1249 ± 273 | 1535 ± 408 | 0.24 |
| Perceptual markers | |||||
| Peak TSS | 7.1 ± 0.8 | 6.8 ± 0.5 | 6.4 ± 1.2 | 6.1 ± 0.7 | 0.88 |
| Mean TSS | 6.4 ± 0.7 | 6.2 ± 0.6 | 6.0 ± 0.6 | 5.8 ± 0.7 | 0.67 |
| Peak TC | 4.2 ± 1.0 | 3.9 ± 0.9 | 3.6 ± 0.8 | 2.2 ± 1.0 | 0.04 |
| Mean TC | 3.3 ± 0.8 | 2.7 ± 0.8 | 2.9 ± 1.0 | 1.7 ± 1.0 | 0.09 |
| Peak RPE | 15.3 ± 3.0 | 15.2 ± 2.2 | 15.0 ± 2.9 | 12.7 ± 2.3 | 0.03 |
| Mean RPE | 13.2 ± 1.6 | 13.0 ± 1.5 | 12.4 ± 2.7 | 12.0 ± 1.8 | 0.81 |
| Hydration status | |||||
| Urinary specific gravity | 1.010 ± 0.008 | 1.011 ± 0.008 | 1.014 ± 0.008 | 1.012 ± 0.007 | 0.43 |
| Urine Osmolarity (mOsmol·kg−1) | 407 ± 284 | 443 ± 277 | 490 ± 307 | 478 ± 357 | 0.88 |
| Change in body mass (%) | 1.1 ± 0.5 | 1.2 ± 0.8 | 0.9 ± 0.5 | 1.5 ± 0.6 | 0.11 |
| Fluid intake (mL) | 523 ± 283 | 546 ± 318 | 589 ± 430 | 475 ± 209 | 0.31 |
| Body composition | |||||
| Body mass (kg) | 76.1 ± 15.0 | 75.4 ± 16.3 | 69.7 ± 10.3 | 71.8 ± 8.9 | 0.46 |
| Body fat (%) | 19.5 ± 4.7 | 18.4 ± 5.2 | 16.1 ± 4.5 | 14.7 ± 4.6 | 0.36 |
| Total body water (%) | 56.1 ± 2.8 | 56.3 ± 3.4 | 57.1 ± 3.4 | 58.6 ± 2.6 | 0.22 |
Bold denotes P value < 0.05.
Hydration measures and body composition values were measured before the heat stress test. P values relate to the main interaction, by two-way ANOVA, of HEAT and CONTROL groups, preintervention, and postintervention.