2007, Piran, Slovenia

2007, Piran, Slovenia 2007, Piran, Slovenia

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Environmental Ergonomics XII Igor B. Mekjavic, Stelios N. Kounalakis & Nigel A.S. Taylor (Eds.), © BIOMED, Ljubljana 2007 Table 1. Rectal (Tcore) and skin (Tsk) temperatures, heart rate (HR), perceived exertion (RPE) and subjective thermal comfort (TC) during exercise before (EX1CON) and after (EX2CON) passive heating. 422 EX1CON EX2CON START END START END Tcore (°C) 37.5 (0.2) 37.9 (0.2) a Tsk (°C) 31.9 (1.3) 33.5 (1.7) a HR (bpm -1 ) 90 (13) 172 (11) a RPE 13.0 (1.1) 15.8 (1.8) a TC 6.7 (0.7) 7.4 (0.8) a a - Significantly different to Start value (p < 0.05) b - Significantly different to corresponding EX1 CON value (p < 0.05) 39.1 (0.4) b 34.8 (2.3) b 125 (14) b 18.2 (1.6) b 8.3 (1.0) b 39.2 (0.4) b 34.5 (2.7) 180 (14) ab 18.8 (1.4) b 8.2 (1.0) Effect of Head-Cooling The effects of passive heating with and without head-cooling on exercise are displayed in Table 2. Head-cooling unexpectedly blunted the rise in Tcore during passive heating by ~0.4°C. This was not an intention of the study, and resulted in Tcore being lower at the start of EX2HC when compared to EX2CON. Head-cooling had no effect on Tsk or heart rate during exercise, but did improve both RPE and TC. Five subjects completed EX2HC, and of the remaining subjects four out of five cycled for longer in EX2HC than during EX2CON, although this effect was not significant (p > 0.05). Table 2. Rectal (Tcore) and skin (Tsk) temperatures, heart rate (HR), perceived exertion (RPE) and thermal comfort (TC) during exercise after passive heating with (EX2HC) and without (EX2CON) head-cooling. EX2CON EX2HC START END START END Tcore (°C) 39.1 ± 0.4 39.2± 0.4 38.6 ± 0.5 b 38.8 ± 0.6 a Tsk (°C) 34.8 ± 2.3 34.5 ± 2.7 34.7 ± 1.4 34.3 ± 1.3 HR (bpm -1 ) 125 ± 14 180 ± 14 a 127 ± 14 182 ± 14 a RPE 18.2 ± 1.6 18.8 ± 1.4 16.7 ± 1.3 b 17.7 ± 1.6 ab TC 8.3 ± 1.0 8.2 ± 1.0 6.8 ± 1.0 b 7.4 ± 1.0 a a - Significantly different to Start value (p < 0.05) b - Significantly different to corresponding EX1 CON value (p < 0.05) DISCUSSION These results confirm that elevating Tcore by passive heating detrimentally affects exercise capacity and perceptual responses during exercise in the heat. These results support the suggestion that hyperthermia is a causative element of the reduced exercise capacity and increased perception in the heat. The addition of head-cooling to passive heating attenuated the negative impact of an increased Tcore on perceptual responses during exercise in the heat, although no such effect was found for exercise capacity. This result is most likely due to head-cooling blunting the rise in Tcore.

Acute and chronic heat exposure REFERENCES Armada-da-Silva, P.A.S., Woods, J., Jones, D.A., 2004. The effect of passive heating and face cooling on perceived exertion during exercise in the heat. Eur. J. Appl. Physiol. 91, 563- 571. Mündel, T., Hooper, P.L., Bunn, S.J., Jones, D.A., 2006. The effects of face-cooling on the prolactin response and subjective comfort during moderate passive heating in humans. Exp. Physiol. 91, 1007-1014. Nunneley, S.A., Reader, D.C., Maldonado, R.J., 1982. Head-temperature effects on physiology, comfort, and performance during hyperthermia. Aviat. Space. Environ. Med. 53, 623-628. 423

Acute and chronic heat exposure<br />

REFERENCES<br />

Armada-da-Silva, P.A.S., Woods, J., Jones, D.A., 2004. The effect of passive heating and face<br />

cooling on perceived exertion during exercise in the heat. Eur. J. Appl. Physiol. 91, 563-<br />

571.<br />

Mündel, T., Hooper, P.L., Bunn, S.J., Jones, D.A., 2006. The effects of face-cooling on the<br />

prolactin response and subjective comfort during moderate passive heating in humans.<br />

Exp. Physiol. 91, 1007-1014.<br />

Nunneley, S.A., Reader, D.C., Maldonado, R.J., 1982. Head-temperature effects on<br />

physiology, comfort, and performance during hyperthermia. Aviat. Space. Environ. Med.<br />

53, 623-628.<br />

423

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