Abstract: | The effects of hyperoxia on submaximal exercise with the self-contained breathing apparatus (SCBA) were studied in 25 males. Each participant completed a graded exercise test for the determination of ventilatory threshold (VT) and then a submaximal practice trial with a normoxic gas mixture. The normoxic (20.93 ± 0.22% O2 ; SUB21) and hyperoxic (40.18 ± 0.73% O2; SUB40) submaximal trials were then administered in a random order. All exercise tests were completed on separate days while wearing firefighting gear and the SCBA. Compared with SUB21, hyperoxia significantly reduced minute ventilation ([Vdot]E ), mask pressure (Pmask), heart rate, blood lactate concentration, perceived exertion, and perceived breathing distress. As expected, hemoglobin saturation remained higher (p<0.05) during SUB40. The reductions in both [Vdot]E and Pmask with hyperoxia imply a reduction in the work of breathing during exercise. Total gas consumption was 10.3 ± 8.1% lower during SUB40 when compared to SUB21, another finding that has significant practical implications for occupational safety. |