ABSTRACT
This study evaluated the effects of hyperoxia (inspired oxygen fraction = 40%) on performance during a simulated firefighting work circuit (SFWC) consisting of five events. On separate days, 17 subjects completed at least three orientation trials followed by two experimental trials while breathing either normoxic (NOX) and hyperoxic (HOX) gas mixtures that were randomly assigned in double-blind, cross-over design. Previously, ventilatory threshold (Tvent) and VO2max had been determined during graded exercise (GXT) on a cycle ergometer. Lactate concentration in venous blood was assessed at exactly 5 min after both the experimental trials and after the GXT. Total time to complete the SFWC was decreased by 4% (p < 0.05) with HOX. No differences 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 significantly decreased rating of perceived exertion (RPE) was also recorded immediately 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 than HR at VO2max (p<0.05). Post-SFWC lactate values were higher (p<0.05) than post-VO2max. These results demonstrate that hyperoxia provided a small but significant increase in performance during short duration, high intensity simulated firefighting work.
Subject(s)
Hyperoxia , Occupational Health , Physical Exertion/physiology , Task Performance and Analysis , Adult , Cross-Over Studies , Double-Blind Method , Female , Fires , Heart Rate , Humans , Hyperoxia/physiopathology , Lactic Acid/blood , MaleABSTRACT
The purpose of this study was to investigate a protocol for the determination of VO2 max utilizing a motor-driven skate treadmill (ST). On separate days, 6 male hockey players completed a ST and a cycle ergometer (BK) VO2 max protocol. The results showed no significant difference between the ST and BK protocols for relative (60.4 +/- 5.09 vs. 59.0 +/- 8.31 ml.kg-1.min-1) and absolute VO2 max values (4.51 +/- 0.50 vs. 4.39 +/- 0.59 L.min-1), respectively. Significantly higher HR max was recorded during the ST protocol (202.3 +/- 4.27 vs. 200.7 +/- 4.55 b.min-1) (p < 0.05). Peak VE and VT were nonsignificant between the two conditions. However, peak f was higher for the ST protocol (63.0 +/- 7.56 vs. 60.2 +/- 7.76 breath.min-1) (p < 0.05). Although the physiological response to both protocols was similar, the ST protocol replicates a hockey stride, which may provide more applicable information for the development of training programs.
