Tympanic temperature and heart rate changes in firefighters during treadmill runs performed with different fireproof...

Six well-trained firefighters performed six treadmill runs at 70% of the velocity at VO2max (Maximal aerobic velocity MAV = 13.2+/-0.3 km h(-1)). A recovery time of 1 week was allowed between trials. The first session was performed by subjects wearing only shorts (i.e. no fire jacket, J0). A similar protocol was applied subsequently to test the physiological effects associated with the wearing of one of five different fire jackets: one leather (J1) and four textile-type jackets: VTN with membrane (J2), VTN without membrane (J3), Vidal with Kermel HTA (Haute Teneur en Aramide i.e. high density in Aramide) (J4); and Rolland with Kermel HTA (J5). All sessions were performed in a randomized order and in laboratory conditions. Exercise with the fireproof jackets resulted in higher tympanic temperature (Tty), heart rate (HR) and body mass loss (BML) changes compared to J0 (p<0.001). The magnitudes of these changes depended on the type of the jacket. Exercise in the leather jacket (J1) resulted in the highest Tty and HR, which differed significantly from values in all other conditions (p<0.001). The exercise-induced increases in Tty wearing jackets J3 and J5 were also significantly (p < 0.05) higher than those observed with jackets J2 and J4. In conclusion, textile jackets induced less HR and Tty stresses than the leather one. The magnitude of the physiological responses induced by textile jackets were correlated to jacket weight. J2 and J4 jackets were more effective in limiting hyperthermia and any potential detrimental effect on the exercise capacity.