A Quantification of the Physiological Demands of the Army Emergency Responder in the Australian Army

Transcription

1 MILITARY MEDICINE, 178, 5:487, 2013 A Quantification of the Physiological Demands of the Army Emergency Responder in the Australian Army Paul J. Tofari, BExSc (Hons); Alison K. Laing Treloar, BExSpSc (Hons); Aaron J. Silk, BHMSc (Hons) ABSTRACT The Australian Defence Force is reviewing the physical demands of all employment categories in the Australian Army to establish valid and legally defensible assessments. The current assessments, performed in physical training attire, are not specific to job demands. Moreover, the fitness standards decrease based on age and are lower for females, and as job requirements are constant, these assessments are counterintuitive. With regard to the Army Emergency Responder employment category, tasks of physical demand in the present study were selected through consultation with subject-matter experts. Participants consisted of 10 qualified Army Emergency Responder soldiers and three noncareer firefighters under instruction. Real-life firefighting scenarios were witnessed by researchers and helped form task simulations allowing measurement of heart rate and oxygen consumption. Peak oxygen consumption ranged from 21.8 ± 3.8 to 40.0 ± 3.4 ml kg 1 min 1 during cutting activities and a search and rescue task, respectively, representing values similar to or higher than the current entry standards. Manual handling tasks were also assessed, with the heaviest measured being two soldiers lifting a 37.7-kg Utility Trunk to 150 cm. The findings provide a quantitative assessment of the physiological demands of Army Emergency Responders, and highlight the need for change in current fitness assessments. INTRODUCTION Physical fitness standards of the Australian Army decrease as age increases, and are lower for females. However, since job-related physical demands remain relatively constant regardless of who performs the task, this method of assessing physical competency is intuitively inappropriate. To address this, the Australian Defence Force (ADF) is currently reviewing physical and physiological demands of employment categories in the Australian Army to establish valid and legally defensible fitness standards for physically demanding jobs. This requires a full and accurate understanding of physical and physiological demands, with findings of such investigations aimed at assisting the review of physical fitness assessments and standards within the ADF. Personnel employed as Army Emergency Responders provide a firefighting and emergency response capability to the ADF. Common and critical physically demanding tasks include ground-level vehicle or aircraft fire suppression, urban search and rescue, stair-climbing while carrying equipment, use of cutting tools, and several other manual handling tasks. However, the ability to accurately quantify physiological demands of firefighters in general is hindered because of the dangerous and often toxic working environment in which Defence Science and Technology Organisation, 506 Lorimer Street, Fishermans Bend, Melbourne, VIC This research, in part, has been presented at an international conference: Tofari PJ, Treloar AK, Silk AJ, and Taylor NAS. (2011). A quantification of the physiological demands of fire suppression. In: Häkkinen K, Kyröläinen H, and Taipale R. Proceedings of the Second International Congress on Soldiers Physical Performance. Jyväskylä, Finland, on May 4 7, ISBN: P The opinions expressed in this article are those of the authors and do not reflect the official policies or positions of the Defence Science and Technology Organisation (Australia) or the Department of Defence. doi: /MILMED-D they operate. These factors affect the collection of accurate measures of metabolic demand (i.e., oxygen consumption), which rely on respiratory gas analysis. Consequently, previous investigators have relied on surrogate indices of metabolic demands, such as heart rate 1 and pulmonary ventilation. 2 The accuracy of predicting metabolic demand from heart rate is adversely affected by external factors, such as heat and stress; both are present in the firefighting environment. 3 In contrast, pulmonary ventilation is not affected by heat, and has been shown to better predict oxygen uptake compared to heart rate. 4 Meanwhile, Bilzon et al 5 collected oxygen consumption data pertaining to the physiological demands of shipboard Navy firefighting, but these data do not quantify the demand of traditional ground-based fire suppression and urban search and rescue. Previous research has detailed the physiological demand of civilian firefighting tasks; however, limited work has been performed in a military setting The current physical fitness assessments for an Army Emergency Responder (2.4-km run, push-ups, and sit-ups) vary greatly from those of other civilian and defence organizations. For example, applicants for the Melbourne (Australia) Metropolitan Fire Brigade are currently required to complete level 9.6 of the 20-m multistage shuttle-run test (estimated oxygen consumption of 45 ml kg 1 min 1 ) as well as a ladder climb and a series of firefighting tasks to assess their muscular strength and endurance during these specific tasks. Firefighters of the Melbourne (Australia) Metropolitan Fire Brigade are not retested once they have passed their recruitment physical testing. Testing for the Canadian firefighters (Candidate Physical Assessment Test) is also performed only at recruitment and is comprised of eight separate firefighting events including carrying equipment, forced entry, and performing a ceiling breach. Similar to their civilian counterparts, the Canadian Forces firefighters perform a test MILITARY MEDICINE, Vol. 178, May

2 incorporating ten separate firefighting tasks completed in a maximum of 8 minutes at an average oxygen consumption of 34.1 ml kg 1 min Therefore, to address the current lack of task specificity in personnel recruitment, this study quantified the physical and physiological demands of the Army Emergency Responder. The outcomes of this study are intended to assist the development of relevant physical employment standards for this specific employment category in the Australian Army. METHODS Subjects As the Army Emergency Responder employment category does not currently contain females, ten qualified male Army Emergency Responders (28.4 ± 6.4 years, 83.7 ± 11.4 kg, and predicted maximum aerobic power 49.7 ± 5.3 ml kg 1 min 1 from multistage fitness test 12 ) participated in the study. In addition, because of facility constraints, 3 healthy male participants (34.3 ± 19.7 years, 72.1 ± 4.1 kg, and maximum aerobic power 58.3 ± 6.6 ml kg 1 min 1 ) under instruction from firefighters of Fire and Rescue New South Wales participated in the urban search and rescue. These subjects were not career firefighters, but were provided necessary training to safely and competently perform the task. All participants provided written, informed consent to procedures approved by the Australian Defence and other relevant Human Research Ethics Committee. Simulation Development To attain accurate and valid physical demand measures of identified critical and demanding tasks, realistic task simulations were developed. These were modeled from staged scenarios with input from subject-matter experts and designed to replicate movement patterns required during the task but excluded environmental dangers such as heat, smoke, and fire; allowing sensitive measurement equipment to be used. To maintain realistic task intensity, Army Emergency Responders were asked to perform each task at the same intensity they would in an emergency situation. Subject-matter experts were on hand to ensure integrity of the simulation performance. Fire Suppression A live-fire scenario incorporating the extinguishing of three vehicles was performed by four Army Emergency Responders. They arrived at the site of the fire in their firefighting vehicle and unloaded equipment, including hoses, hose connections, and breathing apparatus. Two soldiers wore complete firefighting ensemble (including breathing apparatus) and acted as branch operator (lead soldier) and backup man. This observation focused on these two soldiers dragging and operating the charged fire hose (51-mm diameter) toward the burning vehicles and proceeding to extinguish them by intermittently repositioning themselves while adopting different postures and positions. Video footage of the scenario allowed further analysis of movement patterns and changes in body positions. Participant feedback aided with subjectively identifying the most challenging aspects of the task. Subsequent discussions with subject-matter experts enabled a fire suppression simulation to be developed. A subset of soldiers participated in the fire suppression simulation (n = 5; 29.6 ± 7.7 years; 88.3 ± 12.9 kg, predicted maximum aerobic power 52.7 ± 4.3 ml kg 1 min 1 ). The simulation consisted of carrying and maneuvring a charged hose (51-mm diameter), intermittently advancing or repositioning while the hose was on and adopting static standing and kneeling postures with differing spray patterns (jet stream and fog stream) along a set course consisting of 6 stations (Figure 1). The first static position was held for approximately FIGURE 1. Schematic of the fire suppression simulation developed following the observation of a live-fire scenario. The simulation emulates the various movement patterns, postures, and hose configurations used in a real-life situation. Numbers indicate a static position, whereas letters represent a period of movement. 488 MILITARY MEDICINE, Vol. 178, May 2013

3 4 minutes, with the other five held for 1 minute each. These actions and changes in body positions were a close simulation to the live-fire scenario observed. During the simulation, two soldiers wearing full firefighting ensemble operated the hose, a branch operator and a backup man, which again replicated the live-fire scenario and is common practice during real-life fire suppression situations. The physiological demands of performing the role of branch operator were of specific interest. Urban Search and Rescue An urban search and rescue scenario was performed by professional firefighters (Fire and Rescue New South Wales). This scenario was conducted in a multistorey, hot-fire cell environment (heated to 70 C), filled with smoke and with all lights extinguished. During this task, firefighters, wearing full firefighting ensemble including self-contained breathing apparatus, entered the building in pairs dragging a charged fire hose (38-mm diameter). They performed a search of the area with and without the hose, requiring them to ascend and descend flights of stairs. During the activity, firefighters individually performed casualty evacuations (two casualties; 30 and 70 kg, representing a child and an adult, respectively) down the stairs (Table I). A replication of the urban search and rescue scenario was performed by three participants (34.3 ± 19.7 years, 72.1 ± 4.1 kg, maximum aerobic power 58.3 ± 6.6 ml kg 1 min 1 ) and conducted using the same facility without heat and smoke present, although lighting remained extinguished. The simulation replicated the tasks and movement demands of the training scenario. The removal of fire and smoke allowed for sensitive physiological measurement equipment. Stair Climbing Carrying Equipment Army Emergency Responders are frequently required to enter multistorey buildings carrying equipment. Because of the relative simplicity of this task, it was deemed unnecessary to view a staged scenario. Therefore, to assess the metabolic demands of this task, a simulation was created based on parameters (equipment, duration, etc.) described to the researchers by subject-matter experts. Four soldiers (29.3 ± 8.6 years, 83 ± 12.7 kg, predicted maximum aerobic power 49.1 ± 5.3 ml kg 1 min 1 ) wearing full firefighting ensemble performed the simulation in pairs carrying one of three different equipment configurations. Firstly, soldiers ascended four flights of stairs (total vertical distance of 5.95 m) carrying the positive pump ventilator (36 kg) in pairs and continued another 28.5 m along a corridor to the prearranged end point. Once they had reached the end, they set down the positive pump ventilator and descended the staircase in preparation for the second ascent. The next ascent required individually carrying either two rolled hoses (13.6 kg each) or one rolled hose and one Halligan tool (7.6 kg). During the stair ascent, the lead soldier checked the structural rigidity of the staircase. This technique involved TABLE I. Example Timeline of a Subject Performing the Urban Search and Rescue Simulation Time (Minutes) Activity Summary 0:00 1:50 Start Exercise: Enter Building With Charged Hose Commence Search (Simulate Absent Vision) 1:50 2:50 Searching Under Stairs (Without Hose) 2:50 3:07 Searching on Flat Surface (With Hose) 3:07 3:26 Climbing Stairs With Charged Hose 3:26 4:00 Searching on Flat Surface (With Hose) 4:00 4:40 Stop Search and Place Hose on Ground 4:40 5:27 Searching on Flat Surface (Without Hose) 5:27 5:50 Climbing Stairs Without Hose 5:50 6:17 Searching on Flat Surface (Without Hose) 6:17 6:44 Locating Casualty One (70 kg) 6:44 8:07 Pick Up Casualty 8:07 9:00 Dragging Casualty (Over a Step and on Flat Surface) 9:00 9:40 Dragging Casualty (Flat Surface) 9:40 10:40 Dragging Casualty (Backward Down Stairs) 10:40 11:17 Dragging Casualty (Flat Surface) 11:17 12:10 Exit Building With Casualty One 12:10 12:35 Reenter the Building (Without Hose, But Following Hose) 12:35 13:10 Climbing Stairs Without Hose 13:10 13:35 Walking on Flat Surface (Without Hose) 13:35 13:50 Locating Casualty Two (30 kg) 13:50 14:25 Pick Up and Drag Casualty (Flat Surface) 14:25 16:00 Dragging Casualty (Backward Down Stairs) 16:00 16:20 Exit Building With Casualty Two 16:20 16:40 Reenter the Building (Without Hose, But Following Hose) 16:40 17:00 Climbing Stairs Without Hose 17:00 17:35 Retrieve Charged Hose and Descend Stairs 17:35 18:20 Exit Building With Charged Hose 18:20 18:30 Place Hose on Ground 18:30 19:36 Tidying Hose and Finish Simulation stamping the front foot on the next step, as would occur in a real-life scenario. There was no fire or smoke present during this simulation. Using Cutting Tools A vehicle accident scenario was performed by four Army Emergency Responders (same subjects as stair climbing activity) requiring the safe extrication of a casualty (75.3-kg dummy). This scenario consisted of four soldiers arriving at the scene wearing full firefighting ensemble. They proceeded to unpack their vehicle and stabilize the casualty, so they could begin cutting the vehicle for the casualty extraction. The scenario was performed slowly and deliberately, because of caution required when cutting and extracting the casualty to ensure no additional harm. Following the observation, discussions were undertaken with the soldiers who performed the task and with subject-matter experts, all agreeing that the most physically demanding aspect of the scenario was using the cutting equipment. To investigate the demand of operating the common cutting tools (quick-cut saw and cutters), 5-minute simulations MILITARY MEDICINE, Vol. 178, May

4 were created based on the scenario observation, which was further qualified by subject-matter experts. While wearing the complete firefighting ensemble, soldiers used the quick-cut saw (11.5 kg) continually for 5 minutes. The 5-minute simulation using the cutters (11.7 kg) consisted of performing one cut every 30 seconds, totalling 10 individual cuts. The cutters were carried throughout this scenario. Cutting rates were controlled by researchers to ensure they were maintained at the predetermined intensity. Manual Handling In addition to developing and conducting task simulations previously detailed, a profile of manual handling requirements was established. Discussions with Army Emergency Responders enabled the identification of what equipment was commonly lifted and handled as part of the job. Information was measured regarding the common lift heights for items, synonymous with their storage position on a vehicle. Individual items were weighed and this was recorded along with the number of lifters involved. The individual contribution to lifts performed in a team was calculated based on the work of Sharp et al. 13 Rice et al 14 assessed the maximal lifting capacity of men and women to a variety of lifting heights. This research allows us to rank the difficulty of manual handling tasks based on load of the item and the height to which it is lifted. Physiological Demand Measurement During the performance of all tasks, apart from the manual handling investigation, participants were fitted with a heart rate monitor (sampling at 5-second intervals; Polar Team 2 Pro, Polar Electro OY, Kempele, Finland) and wore a portable, open-circuit, expired gas analysis and ventilation system (Metamax 3B; Cortex Biophysik,Leipzig,Germany).The combination of these measurements provided a comprehensive understanding of the physiological demands of the tasks investigated. equivalent to 67.9 ± 0.6% and 80.0 ± 1.3% of maximum heart rate, respectively. The fire suppression simulation took 10:38 minutes (range: 9:55 to 11:20 minutes) to complete at an average oxygen consumption of 2.0 ± 0.2 L 1 (23.2 ± 3.3 ml kg 1 min 1 ) and peak consumption of 2.8 ± 0.3 L min 1 (31.8 ± 3.2 ml kg 1 min 1 ). The mean oxygen consumption for this activity represents 44.1% (±5.3) of the soldiers maximal consumption. A dataset from one simulation performance is displayed in Figure 2. The peaks correspond to periods within the simulation where the branch operator was required to move forward with a charged hose, while spraying a jet stream. During the fire suppression simulation, soldiers achieved the highest mean and peak heart rates of all activities in this study (155 ± 12 and 170 ± 17 beats min 1, respectively), equal to 77.0 ± 7.0 and 86.8 ± 5.3% of maximum heart rate, respectively. The average and peak oxygen consumption of stair climbing carrying equipment was measured as 2.2 ± 0.3 L min 1 (25.9 ± 0.7 ml kg 1 min 1 ) and 3.1 ± 0.4 L min 1 (37.1 ± 1.8 ml kg 1 min 1 ), respectively. This activity, on average, lasted for 9:04 minutes (range: 8:40 to 9:30 minutes), and soldiers maintained a work rate of 53.2% (±6.2) of their maximal oxygen consumption for the entire duration. For the cutting simulation, oxygen consumption peaked at 1.8±0.3Lmin 1 (21.8±3.8mLkg 1 min 1 ), and the soldiers work rate averaged 35.4% (±9.8)ofpeakoxygenconsumption for the duration of the activity (5:00 ± 0:18 minutes), representing the lowest intensity of all tasks. Table II provides a summary of physiological demands of the four tasks assessed. All the tasks in the current work incorporated load carriage, as well as wearing the full firefighting ensemble. This load carriage necessitates a levelofmuscularstrengthand endurance to allow successful task completion. Although Data Treatment/Statistical Analysis Heart rate and oxygen consumption data were synchronized and analyzed as per time stamping of events. Outliers created from equipment measurement errors (i.e., data spikes due to interference) were removed from the analysis via manual observation. Descriptive data presented are mean ± SD. RESULTS The search and rescue simulation took 20:12 minutes (range: 19:18 to 21:12 minutes) to complete at an average and peak oxygen consumption of 1.9 ± 0.2 L min 1 (26.4 ± 1.8 ml kg 1 min 1 ) and 3.1 ± 0.2 L min 1 (42.9 ± 1.0 ml kg 1 min 1 ), respectively. Soldiers were working at an average of 45.7% (±6.2) of peak oxygen consumption. The search and rescue simulation elicited a mean and peak heart rate response of 130 ± 10 and 153 ± 13 beats min 1, respectively, FIGURE 2. Individual oxygen consumption and heart rate data during the performance of the fire suppression simulation. The simulation, a fire hose drill, involved carrying and maneuvering a charged hose (51-mm diameter), intermittently advancing or repositioning while the hose was on and adopting static standing and kneeling postures with differing spray patterns. Data are 5-second averages. 490 MILITARY MEDICINE, Vol. 178, May 2013

5 TABLE II. Metabolic Demands (Assessed via Oxygen Consumption) for Four Common and Critical Tasks of the Army Emergency Responder Duration (Minutes: Mean Oxygen Consumption Mean Oxygen Consumption Peak Oxygen Consumption Peak Oxygen Consumption Task Description Seconds) (L min 1 ) (ml kg 1 min 1 ) (%) (L min 1 ) (ml kg 1 min 1 ) (%) Urban Search and Rescue 20: (0.22) (1.48) 45.7 (6.2) 3.09 (0.19) (1.04) 74.1 (6.5) Stair-Climbing Carrying 09: (0.32) (0.65) 53.2 (6.2) 3.03 (0.41) (1.91) 75.1 (6.2) Equipment Fire Suppression 10: (0.24) (3.34) 44.1 (5.3) 2.78 (0.27) (3.20) 60.5 (6.2) Using Cutting Tools 05: (0.28) (5.53) 35.4 (9.8) 1.80 (0.29) (5.62) 46.4 (11.0) Data presented are mean (SD). the muscular strength and endurance requirements were not directly measured, equipment used throughout the study, as well as other common pieces of equipment utilized in the employment category, were weighed to provide a greater understanding of these requirements. A specialized vehicle (i.e., an emergency vehicle or fire truck) that carries various trade equipment and tools is used in the performance of many Army Emergency Responder duties and tasks, necessitating lifts to and from varying heights of the vehicle. The most difficult lifts undertaken were the Utility Trunk (2 person lift, 20.9 kg each to a 150-cm platform) and the positive pump ventilator (2 person lift 20 kg each to a 148-cm platform). A complete equipment list is contained in Table III. Many of these items were handled on a daily basis, with others used only during emergency response situations. On the basis of the current measurements, the most demanding task performed by the Army Emergency Responder is urban search and rescue. This task requires soldiers to maintain 45.7% of their peak oxygen consumption for 20:12 minutes. All soldiers are required to contribute to any equipment lift; hence an Army Emergency Responder should be able to participate in a 2-person lift of a Utility Trunk (20.9 kg individual contribution) to 150 cm. Furthermore, during an emergency response where soldiers are required to ascend stairs, there is a requirement to lift and carry equipment, the heaviest being two hoses (13.6 kg each) up four flights of stairs. DISCUSSION The current research assessed the physical and physiological demands of common and critical tasks required of soldiers within the Australian Army Emergency Responder employment category. Observation of key tasks via staged scenarios, consultation with subject-matter experts, and analysis of movement patterns allowed for the development of accurate task simulations. These simulations, devoid of environmental hazards (smoke and fire), made it possible to collect measures of metabolic demand that would normally be unattainable when these hazards are present. TABLE III. Common Items Lifted and Handled By Soldiers in the Army Emergency Responder Employment Category During Daily Activities and Emergency Situations Item Description Weight (kg) Number of Lifters Weight Per Lifter (kg) Lift Height (cm) Various Items Pump Positive Pump Ventilator Floating Fire Pump Quick-Cut Saw Cutters Spreaders Utility Trunk Hoses and Attachments Hose (90 mm +30 m) Hose (51 mm +30 m) Distribution Valve Intake Valve Nozzle Clothing Self-contained Breathing Apparatus* Turn Out Gear* 3.9 NA 3.9 Boots* 2.5 NA 2.5 Helmet* 1.6 NA 1.6 *Items are worn on the soldiers person; Weight per lifter is calculated using the equation outlined in Sharp et al 5. MILITARY MEDICINE, Vol. 178, May

6 The highest metabolic demands measured in this study were during urban search and rescue (26.3 ± 12.4 and 40.0 ± 3.4 ml kg 1 min 1, average and peak, respectively) and stair-climbing while carrying equipment (25.9 ± 0.7 and 37.1 ± 1.8 ml kg 1 min 1, average and peak, respectively). These data are comparable to previous research assessing the physiological demands of firefighting. Gledhill et al 8 observed oxygen consumption of 44 ml kg 1 min 1 in firefighters while carrying equipment up high-rise stairs, an operation that lasted 128 seconds. It is unclear whether the task in the work of Gledhill et al 8 was performed within a series of other tasks, or how many stories were climbed. Holmer and Gavhed 9 reported similarly high oxygen consumption (43.8 ml kg 1 min 1 ) as Gledhill et al 8 for a stairclimbing task carrying equipment. However, Holmer and Gavhed 9 incorporated stair climbing (three flights of stairs) as part of a series of other firefighting tasks, not in isolation as the present work. It should be noted that building heights are generally 3 to 4 stories high in Australian Army garrison bases, hence accounting for the slightly reduced demand compared to the high-rise task. This study also provides data pertaining to the oxygen demand of fire suppression while maneuvring and using a charged fire hose. Bilzon et al 5 presented oxygen consumption data for a boundary cooling hose task performed by Naval firefighters wearing a full ensemble, with the peak being 23 ml g 1 min 1. This is lower than the ml kg 1 min 1 observed in the current study; however, the Naval firefighting task, although requiring dynamic hose movement, was performed statically for a shorter duration (4 vs. approximately 12 minutes).in addition, the hose was set to ragged spray providing less pressure than the high-pressure stream used herein. This finding underlies the importance of accurate task simulations replicating specific movement patterns of tasks. There are currently no employment-category-specific physical entry standards in the Australian Army. As such, the current generic employment standard for aerobic power is based on a 2.4-km running test performed in physical training attire. To maintain employment as an Army Emergency Responder, a soldier must complete the run in a specified time. This run-time standard reduces with age, and is lower for females. 15 To be deemed fit for service, males and females aged 25 years and under require a predicted maximal aerobic powerof45.6mlkg 1 min 1 and39.3mlkg 1 min 1,respectively, equivalent to run times of 11:18 minutes for males and 13:30 minutes for females. By the age of 36, this standard for males and females is reduced to 42 ml kg 1 min 1 and36mlkg 1 min 1 (12:42 and 15:00 minutes), respectively. Therefore, if the current 2.4-km running test is performed maximally, as intended, soldiers above the age of 36 will not possess the physiological capacity to perform their job, as data from the present study have indicated peak oxygen consumption above 42 ml kg 1 min 1. Furthermore, the current research defines a requirement to work at 26.3 ml kg 1 min 1 for approximately 20 min. This task will become increasingly difficult as the current aerobic assessment standard reduces for age and is lower for females; yet demands of critical and physically demanding tasks are independent of both factors. Although no females participated in this study, previous research indicates that relative oxygen consumption does not differ between males and females during firefighting tasks. 11 As a result, the current aerobic power assessment for this employment category is deemed inappropriate as there will ultimately be a small margin between a soldier s maximal aerobic power and job requirement or, in some instances, the latter will surpass the former. Wu and Wang 16 have shown that a person s ability to sustain work decreases exponentially as intensity increases, and working under fatigue, induced by this intensity, creates a greater likelihood of injury. 17,18 Furthermore, it is assumed that the work intensity during actual firefighting may be higher than that measured in the current work because of inherent job hazards. Therefore, an assessment measuring a soldier s ability to become an Army Emergency Responder should incorporate a safety margin between a soldier s capacity and job requirements. Previous research has indicated a safety margin of 5% is appropriate to ensure soldiers are capable of repeat performance in their job. 19 This safety margin would also allow for worst case scenarios, such as when a colleague becomes injured and needs rescuing. While performing the role of an Army Emergency Responder, soldiers must wear personal protective equipment weighing 22.5 kg (including self-contained breathing apparatus). In fact, carrying external load, including tools and equipment, is a vital part of their role. This factor should be considered when assessing the Army Emergency Responders aerobic power, as is the case in other fire services worldwide. 11 As the current Australian Army assessment does not incorporate external load, it does not inform assessors as to a soldier s ability to perform their work in realistic working conditions. Furthermore, an assessment such as this is inappropriate for measuring aerobic performance in load-carriage tasks due to body-mass bias. A heavier soldier performs their role carrying a lower percentage of their bodyweight in external load, making the job easier when compared to a light soldier. 20 However, lighter individuals generally perform better in a timed distance run wearing physical training attire (the current assessment) but not during aerobic activities incorporating load carriage. 21 Taking into account all the above information, an appropriate assessment of an Army Emergency Responder s aerobic power would incorporate soldiers wearing external load equal to their operational uniform (22.5 kg), a maximum aerobic power of at least 45 ml kg 1 min 1, and ability to maintain 27.6 ml kg 1 min 1 for a minimum of 20 minutes. This assessment would preferably incorporate simulations of job-specific tasks performed in series, representing realistic task scenarios. The recommended aerobic power standard incorporates a safety margin, generated by adding a 5% safety margin to measured urban search and rescue task 492 MILITARY MEDICINE, Vol. 178, May 2013

7 demands, and should remain constant throughout employment as an Army Emergency Responder, regardless of age or sex. Similar to the aerobic power standard, muscular strength and endurance assessments for the Army Emergency Responder are age biased and lower for females. To be fit for service, males and females aged 25 years and under must perform a minimum of 40 and 21 push-ups, respectively, in 2 minutes and 70 sit-ups to a cadence. Timed push-ups and sit-ups to a cadence are considered a test of muscular endurance, but are movement patterns that are not common or required in this employment category. Furthermore, these assessments are biased toward light individuals as they measure a soldier s capacity relative to bodyweight. 20 Previous research suggests a correlation between muscular endurance tests (push-ups and sit-ups) with firefighting job performance However, as discussed, these tests are biased to light individuals. Furthermore, the current push-up and sit-up assessments are not a feasible measure of strength, especially in this environment, as an Army Emergency Responder is required to lift role-specific equipment, and there is an absolute strength requirement (i.e., contribute to a lift of 37.7 kg to 150 cm) for the job. This strength requirement, similar to the aerobic requirement, will require a safety margin; so soldiers are not performing common lifts of their job at close to their maximal capacity. Additionally, this protects soldiers who may be fatigued while performing their role by not straining them maximally. Therefore, to assess the muscular strength of Army Emergency Responders, an assessment should incorporate a discrete lifting task ensuring soldiers are capable of safely performing their most difficult lift submaximally. Savage et al 25 outline a psychophysical approach to setting safe manual handling standards. Based on their method, a muscular strength assessment for Army Emergency Responders should comprise a discrete lift of 24.9 kg (in the form of a box lift and place) to 150 cm, based on lifting the Utility Trunk. An Army Emergency Responder is also required to lift and carry equipment for prolonged periods, such as two 13.6-kg hoses upstairs and along a corridor, a charged hose for approximately 10 minutes, and cutting equipment (11.7 kg) for 5 minutes. Current assessments measuring muscular endurance (push-ups and sit-ups), although providing some relationship to firefighting tasks, do not measure a soldier s ability to lift and carry equipment with the ecological validity of a task-specific assessment. An appropriate assessment would involve lifting and carrying an item in each hand (replicating the hose carry upstairs). In this instance, the safety margin can be incorporated in task duration (i.e., approximately 10 minutes), and again should remain constant throughout employment of the Army Emergency Responder, regardless of age and sex. This study, through the use of representative task simulations, enabled accurate quantification of the physical and physiological demands of the Army Emergency Responder employment category. On the basis of our findings, an assessment battery designed to establish job-specific physical fitness should incorporate wearing task-specific clothing, incorporating operational loads simulating common jobspecific equipment, and emphasizing activities that better replicate the working environment. In addition, specific muscular strength and endurance assessments, such as a discrete lift and place and a lift and carry assessment, should be incorporated. ACKNOWLEDGMENTS The project from which this research was derived was supported by the ADF. REFERENCES 1. 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