The effects of hyperoxia on performance during simulated firefighting work

This study evaluated the effects of hyperoxia (inspired oxygen fraction = 4 0%) on performance during a simulated firefighting work circuit CSR;VC) con sisting of five events. On separate days, 17 subjects completed at least th ree orientation trials followed by two experimental trials while breathing either normoxic (NOX) and hyperoxic (HOX) gas mixtures that were randomly a ssigned in double-blind, cross-over design. Previously, ventilatory thresho ld (Tvent) and YO(2)max had been determined during graded exercise (GXT) on a cycle ergometer. Lactate concentration in venous blood was assessed at e xactly 5 min after both the experimental trials and after the GXT. Total ti me to complete the SFWC was decreased by 4% (p < 0.05) with HOX. No differe nces were observed in individual event times early in the circuit, however HOX resulted in a 12% improvement (p < 0.05) on the final event. A signific antly decreased rating of perceived exertion (RPE) was also recorded immedi ately prior to the final event. No differences were observed in mean heart rate or post-exercise blood lactate when comparing NOX to HOX. Heart rates during the SFWC (both conditions) were higher than HR at Tvent, but lower t han HR at VO(2)max (p < 0.05). Post-SFWC lactate values were higher (p < 0. 05 than post-VO(2)max. These results demonstrate that hyperoxia provided a small but significant increase in performance during short duration, high i ntensity simulated firefighting work.