Introduction
Firefighting is an hazardous task requiring heavy workload that may be limited by air cylinder reserve. It is likely that increased fitness can lead to a better air economy and duration at a given heavy work intensity.
Objectives
1. The main purpose of this study was to measure if the fastest firefighters during a simulated work circuit (SWC) were those who consumed less air at a given intensity.
2. Secondly, this study aimed to measure if the fastest firefighters during a SWC were the most performant at a graded walking test (GWT).
3. Thirdly, the aim was to determine if there were any central and peripheral physiological parameters correlated with performance at a SWC.
Materials & Methods
Thirteen males firefighters (28.4 ± 5.1 years; 175.5 ± 4.5
cm; 84.4 ± 9.0 kg; VO2peak: 47.8 ± 5.1 mlO2·min-1·kg-1)
performed a graded walking test (GWT), a 10 METS treadmill test (T10) and a simulated work circuit (SWC) similar to the test described by Deakin et al. (1996). The
intensity of 10 METS represents the average VO2 of work
associated with completion of the fire fit test work simulation described by Deakin et al. (1996) at a specified performance standard of 8 minutes (Dreger and Petersen 2007).
Oxygen consumption (VO2), ventilation (VE), respiratory
equivalent for oxygen (VE/VO2) and respiratory exchange
ratio (RER) were measured during GWT using gas analyzer cart. Heart rate (HR) was measured during every test. Difference of concentration of hemoglobin (HbDiff) and tissue saturation index (TSI%) were measured by near-infrared spectroscopy (NIRS) during each test.
Relationship between performance in a simulated firefighting work circuit, work
economy and muscle oxygenation
Gendron P., Freiberger E., Laurencelle L., Trudeau F., Lajoie C.*
Département des sciences de l’activité physique de l’UQTR
Results
Table 1 : Pearson and Kendall's τ correlations matrix.
PSI, psi consumed.
*Significant at P < 0.05. **Significant at P < 0.01.
Table 2 : Pearson and Kendall's τ correlations matrix.
RER, respiratory exchange ratio; VE/VO2, ventilatory equivalent ratio for oxygen; VE, ventilation; HR, heart rate.
*Significant at P < 0.05. **Significant at P < 0.01.
Conclusions
1. These results demonstrated that the fastest
firefighters at SWC had a lower pulmonary air ventilation at a given work intensity. The observed increased work economy could allow firefighters in
better physical condition to perform a heavy workload
task in the heat longer.
2. Furthermore, the fastest firefighters at the SWC were the most performant at the GWT.
3. Finally, a better VO2peak and a better oxygen
extraction rate of skeletal muscle were correlated with better performance at the SWC.
1. Deakin, J.M., Pelot, R.P., Smith, J.M., Stevenson, J.M., Wolfe, L.A., Lee, S.W., et al. 1996. Development of a bona fide physical maintenance standard for CF and DND fire fighters: 119. Queen’s University, Kingston, Ont. 2. Dreger, R. W., & Petersen, S. R. (2007). Oxygen cost of the CF-DND fire fit test in males and females. Applied Physiology, Nutrition, and Metabolism, 32(3), 454-462.
Pearson and Kendall's τ correlations matrix.
PSI, psi consumed. *Significant at P < 0.05. **Significant at P < 0.01. PSI, psi consumed. *Significant at P < 0.05. **Significant at P < 0.01.
SWC completion time PSI 500 1000 1500 2000 2500 3000 Global τ N 13 13 13 11 11 9 r -0.339 -0.397 -0.454 -0.512* -0.571* -0.630* 1.000** SWC completion time Grade (%) Global τ 2 4 6 8 10 12 RER 0.341 0.406 0.599* 0.613* 0.717** 0.653* 0.867* VE/VO2 0.258 0.237 0.312 0.442 0.657** 0.734** 0.867* VE 0.117 0.157 0.232 0.392 0.484* 0.440 0.867* %HRmax 0.259 0.429 0.508* 0.758** 0.761** 0.692** 0.733* -70 -60 -50 -40 -30 -20 -10 0 300 320 340 360 380 400 420 [Hb Dif f] (A.U.) SWC completion time (s) HbDiff at SWC Max [HbDiff]; r = 0.725, P < 0.01. Mean [HbDiff]; r = 0.768, P < 0.01. -40 -35 -30 -25 -20 -15 -10 -5 0 300 320 340 360 380 400 420 TSI % SWC completion time (s) TSI% at SWC Max TSI%; r = 0.617, P < 0.05. Mean TSI%; r = 0.604, P < 0.05. 300 400 500 600 700 800 900 1000 300 320 340 360 380 400 420 T ime to us e 1850 ps i (s ) SWC completion time (s)
Time to use 1850 psi vs SWC completion time
r = -0.495, P < 0.05. 36 38 40 42 44 46 48 50 52 54 56 58 300 320 340 360 380 400 420 VO 2 peak (ml· kg -1 ·min -1 ) SWC completion time (s)
VO2peak vs SWC completion time
r = -0.924, P < 0.001. 600 650 700 750 800 850 900 950 1000 300 320 340 360 380 400 420 GWT tim e t o ex haus tion (s) SWC completion time (s)
GWT time to exhaustion vs SWC completion time
