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

Six well-trained firefighters performed six treadmill runs at 70% of the ve locity 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 p erformed by subjects wearing only shorts (i.e. no fire jacket, J0). A simil ar protocol was applied subsequently to test the physiological effects asso ciated with the wearing of one of five different fire jackets: one leather (J1) and four textile-type jackets: VTN(TM) with membrane (J2), VTN(TM) wit hout membrane (J3), Vidal(TM) with Kermel(R) HTA (Haute Teneur en Aramide i .e. high density in Aramide) (J4); and Rolland(TM) with Kermel(R) HTA (J5). All sessions were performed in a randomized order and in laboratory condit ions. Exercise with the fireproof jackets resulted in higher tympanic tempe rature (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 an d J4. In conclusion, textile jackets induced less HR and Tty stresses than the leather one. The magnitude of the physiological responses induced by te xtile 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.