Abstract
Oral (Tor) and tympanic (Tty) temperatures were examined as alternatives for rectal temperature (Tre) as a heat strain indicator. Subjects were 20 male volunteers (age=18–33yr). A workload was determined in chemical protective clothing (CPC) by having the subject walk on a treadmill until a VO2 uptake of 1.33 (L/minute (≈650 W) was reached. At a second session subjects donned CPC and walked on the treadmill at the previously determined workload until Tre reached 39°C, or heart rate reached 185 bpm, or volitional fatigue, i.e., one work cycle. Subjects then rested for 48 minutes. This cycle continued for 4 hours or until absolute fatigue at <4 hours. Heart rate, Tor, Tty, Tre, and mean skin temperature were recorded every 10 minutes and at the end of work. A paired t-test was used to determine if a significant difference in the magnitude of temperature increase in Tor and Tty as compared with Tre existed. No significant difference (p>0.05) was observed in Δ Tor against Δ Tre at 20, 30, 40, and 60 minutes of exercise, but Δ Tor failed to display nonsignificant mean differences consistently throughout the test. However, Δ Tty displayed no significant mean differences (p>0.05) against Δ Tre throughout the test. Tty significantly correlated with Tre at the 30- and 50-minute intervals (p≤0.05) and the end reading (p≤0.01.) A repeated measures analysis of variance showed no significant difference between Tty and Tre over time. It was concluded that Tty has potential as a heat strain indicator for workers wearing CPC in the field, but Tor does not.