Respiratory gas exchange and physiological demands during a fire fighter evaluation circuit in men and women

We examined the oxygen uptake (VO₂) and carbon dioxide output (VCO₂) during completion of a circuit developed for testing fire fighters and related performance time to laboratory measures of fitness. Twenty-two healthy university students (ten women) were trained in the tasks then performed the circuit as quickly as possible. Breath-by-breath gas exchange and heart rate were continuously measured with a portable system. Median circuit time was 6:13 (min:s, 25–75% = 5:46–6:42) for men and 7:25 (25–75% = 6:49–10:21) for 8 women finishers (P = 0.023), and VO₂ averaged 68 and 64% VO₂max for the men and women during the circuit. Both men and women had high respiratory exchange ratios (>1.0) suggesting marked anaerobic energy contribution. Physiological variables associated with circuit time were assessed by backward stepwise regression yielding a significant model that included only peak work rate during arm cranking exercise as a function of circuit completion time across men and women combined (P < 0.001). For men, but especially for women, the time required for the simulated victim drag (68.2 kg mannequin) was positively correlated with total time to complete the other circuit elements (r = 0.51, r = 0.96 respectively). The simple correlation between circuit time and VO₂max (mL/kg/min) revealed poor relationships for men (r = −0.37, P > 0.05) and women (r = 0.20, P > 0.05). These data demonstrated that upper body fitness as reflected by peak work rate during arm cranking correlated with total circuit time for the men and women in our population sample.