The Impact of Heat Exposure and Sleep Restriction on Firefighters’ Work Performance and Physiology during Simulated Wildfire Suppression
Abstract
:1. Introduction
2. Materials and Methods
2.1. Participants and Screening
2.2. Experimental Protocol
2.3. The Physical Work Circuit
2.4. Physiological Measures: Heart Rate, Core Temperature, Hydration, and Polysomnography
2.5. Perceptual Responses
2.6. Statistical Analyses
3. Results
3.1. Physical Task Performance
3.2. Heart Rate
3.3. Core Temperature and Hydration
3.4. Perceptual Responses
4. Discussion
5. Conclusions
Acknowledgments
Author Contributions
Conflicts of Interest
References
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SR | HOT + SR | |
---|---|---|
N | 17 | 13 |
Age (y) | 39 ± 15 | 41 ± 17 |
Weight (kg) | 93.8 ± 20.2 | 83.8 ± 14.3 |
Height (m) | 1.78 ± 0.07 | 1.76 ± 0.04 |
BMI (kg·m−2) | 29.6 ± 5.5 | 27.0 ± 4.3 |
Service (y) | 10 ± 6 | 14 ± 12 |
Males: Females | 15:2 | 12:1 |
Habitual daily caffeine intake (mg) | 150 ± 80 | 155 ± 83 |
Habitual weekly physical activity (sessions per week) | 2.4 ± 2.2 | 3.0 ± 2.9 |
Task | Parameters | Work to Rest Ratio | Times Completed | Performance Measure | Simulates |
---|---|---|---|---|---|
Rake | Rake the contents of a box (2 m × 0.8 m) filled with 29 kg of large and small tyre crumbs from one side to the other using a rake-hoe. | 90 s work 60 s rest 90 s work | 1 | Number of completed boxes raked (movement of material from one side to the other). | Clearing ground debris to create a mineral earth firebreak [28] |
Lateral repositioning | Hold a weighted hose (length 3.5 m) and walk in an 11-m arc. Two platforms (68 × 28 × 15 cm) served as obstacles. One platform was required to be stepped on, the other stepped over. | 30 s work 30 s rest × 4 | 4 | Number of semi circles completed (later converted to distance covered). | Moving a charged hose sideways from a fixed point, whilst negotiating fireground debris (e.g., fallen logs, tree roots; [11]). |
Hose rolling | Roll up a 16-m (folded in half to a length of 8 m) hose to an operational standard. Must be rolled along the ground. Firefighter must move along the length of the hose rather than pulling towards them. | 60 s work 60 s rest 60 s work | 1 | Absolute number of hoses rolled during the allocated work period. | Rolling up a hose for storage [11]. |
Charged hose advance | Drag a 2-m weighted hose attached to a 15-kg weighted tyre up and down a marked distance of 8 m. | 65 s work 55 s rest 65 s work | 1 | Absolute number of completed hose drags from one end of the 8-m line to the other. | Walking forward with hose filled with pressurised liquid towards a fire front [11]. |
Black out hose work | Drag a 2-m weighted hose connected to a 15-kg bag around the perimeter of a 10-m square (2.5 × 2.5 m) pausing for 3 s at each corner (timed by a metronome). | 90 s work 60 s rest 90 s work | 2 | Number of full rotations around the square (later converted to distance covered). | The stop-start movements that firefighters perform when extinguishing smouldering debris, during post-fire clean up [11]. |
Task | Work Performance (m or m2) | Average Heart Rate (% of HR Max) | RPE | Thermal Sensation | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Day | Day | Day | Day | |||||||||||
1 | 2 | 3 | 1 | 2 | 3 | 1 | 2 | 3 | 1 | 2 | 3 | |||
Black out hose | SR | Mean | 167.9 | 167.0 | 167.4 | 67 | 62 | 62 | 12.0 | 12.3 | 12.3 | 4.5 | 4.7 | 4.7 |
SD | 16.0 | 17.1 | 18.6 | 7 | 5 | 7 | 1.3 | 1.2 | 1.2 | 0.8 | 0.7 | 0.6 | ||
HOT + SR | Mean | 149.4 | 139.3 | 140.2 | 71 | 63 | 61 | 12.0 | 11.9 | 12.1 | 5.4 | 5.3 | 5.6 | |
SD | 17.8 | 19.4 | 15.4 | 12 | 9 | 8 | 1.6 | 1.9 | 1.8 | 0.9 | 1.0 | 0.9 | ||
Charged hose advance | SR | Mean | 99.9 | 104.4 | 108.0 | 75 | 70 | 70 | 14.2 | 14.3 | 14.5 | 5.4 | 5.5 | 5.3 |
SD | 12.3 | 16.1 | 17.6 | 8 | 7 | 8 | 2.1 | 1.7 | 1.8 | 1.0 | 1.0 | 0.9 | ||
HOT + SR | Mean | 91.3 | 88.9 | 89.9 | 82 | 73 | 70 | 15.3 | 14.7 | 15.2 | 6.0 | 5.9 | 6.1 | |
SD | 18.2 | 19.5 | 19.8 | 13 | 11 | 10 | 2.0 | 2.1 | 2.3 | 0.7 | 0.8 | 0.9 | ||
Lateral hose repositioning | SR | Mean | 650.5 | 656.5 | 679.7 | 67 | 62 | 63 | 11.2 | 11.4 | 11.4 | 4.3 | 4.5 | 4.6 |
SD | 76.7 | 76.8 | 73.3 | 7 | 6 | 7 | 0.9 | 1.0 | 1.0 | 0.7 | 0.5 | 0.5 | ||
HOT + SR | Mean | 573.8 | 560.7 | 550.6 | 70 | 63 | 61 | 10.8 | 11.1 | 11.9 | 5.2 | 5.2 | 5.5 | |
SD | 59.1 | 69.2 | 67.1 | 11 | 9 | 8 | 0.8 | 0.7 | 0.9 | 0.8 | 0.8 | 0.7 | ||
Hose rolling | SR | Mean | 16.9 | 19.0 | 20.5 | 68 | 63 | 64 | 11.6 | 12.1 | 12.4 | 4.3 | 4.5 | 4.6 |
SD | 3.6 | 3.9 | 5.0 | 8 | 7 | 8 | 1.3 | 1.0 | 1.0 | 0.7 | 0.6 | 0.6 | ||
HOT + SR | Mean | 17.4 | 19.5 | 19.9 | 72 | 65 | 63 | 11.9 | 11.9 | 12.8 | 5.3 | 5.4 | 5.7 | |
SD | 4.5 | 6.0 | 5.6 | 12 | 10 | 9 | 2.3 | 1.7 | 1.9 | 1.0 | 0.9 | 0.8 | ||
Rake | SR | Mean | 4.6 | 4.9 | 5.1 | 75 | 69 | 70 | 14.0 | 14.0 | 14.0 | 5.2 | 5.3 | 5.2 |
SD | 0.6 | 0.8 | 0.8 | 8 | 6 | 8 | 1.7 | 1.2 | 1.3 | 0.8 | 0.8 | 0.9 | ||
HOT + SR | Mean | 4.6 | 4.8 | 4.8 | 80 | 71 | 68 | 14.7 | 14.5 | 14.4 | 6.3 | 6.1 | 6.4 | |
SD | 1.1 | 1.2 | 1.2 | 13 | 11 | 9 | 2.1 | 2.2 | 2.1 | 0.9 | 0.9 | 0.9 | ||
Static hose hold | SR | Mean | - | - | - | 66 | 59 | 59 | 12.7 | 12.7 | 12.6 | 5.0 | 5.1 | 5.0 |
SD | - | - | - | 8 | 6 | 6 | 1.3 | 1.4 | 1.4 | 0.8 | 0.8 | 0.9 | ||
HOT + SR | Mean | - | - | - | 75 | 64 | 60 | 13.4 | 13.2 | 13.4 | 6.1 | 6.0 | 6.2 | |
SD | - | - | - | 14 | 12 | 9 | 3.2 | 2.5 | 2.5 | 0.8 | 0.8 | 0.7 |
Day | ||||||
---|---|---|---|---|---|---|
1 | 2 | 3 | ||||
SR | HOT + SR | SR | HOT + SR | SR | HOT + SR | |
Core Temperature | ||||||
Daily core temperature (°C) | 37.61 ± 0.21 | 37.85 ± 0.23 | 37.47 ± 0.29 | 37.66 ± 0.28 | 37.46 ± 0.25 | 37.58 ± 0.27 |
Hydration | ||||||
Urine specific gravity | 1.015 ± 0.006 | 1.012 ± 0.008 | 1.011 ± 0.004 | 1.011 ± 0.008 | 1.011 ± 0.005 | 1.009 ± 0.007 |
Fluid in volume (mL) per circuit | 1395 ± 344 | 2108 ± 367 | 952 ± 349 | 1443 ± 228 | 823 ± 602 | 1523 ± 318 |
Urine out volume (mL) per circuit | 676 ± 293 | 609 ± 405 | 671 ± 316 | 651 ± 255 | 602 ± 298 | 681 ± 278 |
Motivation | ||||||
Effort sensation per circuit (%) | 76 ± 11 | 81 ± 12 | 75 ± 11 | 77 ± 12 | 76 ± 9 | 76 ± 11 |
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Vincent, G.E.; Aisbett, B.; Larsen, B.; Ridgers, N.D.; Snow, R.; Ferguson, S.A. The Impact of Heat Exposure and Sleep Restriction on Firefighters’ Work Performance and Physiology during Simulated Wildfire Suppression. Int. J. Environ. Res. Public Health 2017, 14, 180. https://doi.org/10.3390/ijerph14020180
Vincent GE, Aisbett B, Larsen B, Ridgers ND, Snow R, Ferguson SA. The Impact of Heat Exposure and Sleep Restriction on Firefighters’ Work Performance and Physiology during Simulated Wildfire Suppression. International Journal of Environmental Research and Public Health. 2017; 14(2):180. https://doi.org/10.3390/ijerph14020180
Chicago/Turabian StyleVincent, Grace E., Brad Aisbett, Brianna Larsen, Nicola D. Ridgers, Rod Snow, and Sally A. Ferguson. 2017. "The Impact of Heat Exposure and Sleep Restriction on Firefighters’ Work Performance and Physiology during Simulated Wildfire Suppression" International Journal of Environmental Research and Public Health 14, no. 2: 180. https://doi.org/10.3390/ijerph14020180