Characterising the physical demands of critical tasks across the Royal Australian Air Force

Abstract

BACKGROUND:

Militaries have historically utilised generic physical fitness tests to assess physical readiness, but there has been a recent shift to develop physical employment standards (PES) based on actual job demands.

OBJECTIVE:

The purpose of this investigation was to characterise the physical demands of critical tasks performed by Royal Australian Air Force (RAAF) personnel to inform PES development.

METHODS:

Job task analysis were performed for 27 RAAF trades. Criterion tasks were identified through a systematic approach involving workshops and field-observations. The identified tasks were assessed for dominant physical capacity and grouped into movement-based clusters. Psychophysiological measures were collected from personnel performing the tasks.

RESULTS:

Of 87 criterion tasks, 92% were characterised as manual handling dominant. Across these 87 tasks the principal physical capacities were: muscular strength (59%), muscular endurance (52%) and cardiorespiratory endurance (39%). The most common movement clusters were Lift to Platform (44%) and Lift and Carry (38%). Lift to Platform tasks required lifting to a median height of 1.32 m (1.20 –1.65 m) and a median mass of 25.0 kg (21.0 –28.9 kg) per person. Median carry mass was 25.0 kg (22.4 –36.1 kg) per person and distance was 26.0 m (17.5 –50.0 m). Median task mean ’Vdot;O₂, HR and RPE were 1.8 L.min^- 1 (1.5–2.2 L.min^- 1), 137 b.min^- 1 (120–144) and 13 (12–14).

CONCLUSIONS:

The high proportion of manual handling criterion tasks emphasises the importance of these activities and the underlying physical capacities for RAAF personnel. Current fitness assessments are unlikely to predict job task performance.

Keywords

Physical employment standards job task analysis physical demands analysis muscular strength muscular endurance cardiorespiratory endurance lift lift and carry military

1 Introduction

Historically, military organisations have utilised generic physical fitness tests that are based upon age and sex-adjusted cut points to provide an evaluation of functional physical capacity and suitability to enter or continue military service. It is increasingly understood that these generic assessments of physical fitness, such as, push-ups, sit-ups, and unloaded running do not accurately evaluate the range of physical attributes that are critical for military service. Indeed, generic assessments are typically poor predictors of occupational performance, having low content validity and provide limited insight into workplace physical readiness [1 –6].

Manual handling is a predominant requirement within the Australian Army comprising 79% of the physically demanding tasks [7]. However, generic physical fitness assessments such as push-ups, pull-ups, and sit-ups have been clearly shown to be poor predictors of performance for discrete manual handling tasks such as lifting items to a 1.5 –1.55 m truck tray [2, 5] and repetitive army manual handling task simulations such as loading an artillery gun or bombing up a main battle tank [2]. For prolonged weight-bearing tasks such as load carriage, weak to moderate associations have been observed with absolute and or relative ’VO₂_max from unloaded running assessments [1 , 3–6]. Additionally, generic physical fitness assessments impose a systematic bias against heavier personnel, whom are often observed to have performed better in the job task [1 , 9]. The body mass bias and lack of association with occupational task performance necessitate physical fitness assessments that reflect the critical and physical demands upon military personnel.

Prior to determination of physical assessment protocols, it is necessary to first understand the nature and characteristics of the critical and physically demanding job tasks for an occupational or role [10, 24]. This evaluation stage is particularly important in the military given the diverse occupations and roles, many of which require the performance of unique physically demanding tasks. Accordingly, many military organisations have developed physical employment standards (PES) in recent years [10]. This evaluation requires a job task analysis be performed to determine the essential (or ‘criterion’) physically demanding tasks [7, 10]. A job task analysis normally consists of a series of workshops and observations to identify, quantify, characterise, and verify the criterion physically demanding task [7, 10]. Criterion tasks therefore represent the most physically demanding tasks that are considered essential for all personnel to complete safely within an occupation or role [7, 10].

Through the development of robust and valid physical assessment standards and cut-scores employers can discern those personnel who do not have sufficient relevant physical capacity to meet the critical demands of the occupational or role. Personnel who are not physically capable of performing job tasks are more susceptible to injury [11, 12] and can negatively impact the operational effectiveness of the team. This insight gained through PES development facilitates improved setting of recruiting and incumbent fitness standards, shaping of physical conditioning, informing training pipelines and policy.

To date, the majority of military PES literature has focused on ground forces (e.g. Army), as they are considered to have some of the greatest physical demands such as load carriage and manual material handling. In contrast, there are limited published data on the physical demands of Air Force personnel, especially at an organisational level across trades, with research focused on specialist groups that do not necessarily represent the broader workforce. Treweek et al. [13] investigated eight criterion tasks of the Royal Air Force (RAF) Regiment branch which is a ground fighting force within the British RAF while Gruse et al. [14] examined criterion tasks for United States (U.S.) Air Force explosive ordnance disposal and battlefield airmen. Two reports detail the physical demands of 14 operational tasks considered core to all British RAF personnel [15, 16] and one report investigated criterion tasks of U.S. Battlefield Airmen [17]. Several studies have also investigated fitness assessments for Air Force but do not provide details of the job task analysis stage [18 –23]. No study has comprehensively evaluated the physical demands of essential tasks across a significant portion of an Air Force.

Currently, the Royal Australian Air Force (RAAF) assesses the physical readiness of personnel through the generic predictive tests of push-ups, sit-ups, and 2.4-km run, however, it is unclear how these tests relate to occupational performance. Quantifying the physical demands of tasks across the Air Force is required to then understand how effective the current tests are at assessing the physical suitability of Air Force personnel for different occupations and roles. The purpose of this investigation was to characterise and quantify the physically demanding criterion tasks across 27 trades within the RAAF. This will allow the development of appropriate physical assessments and standards, conditioning programs, and personnel selection, which in turn should result in a more productive and physically resilient workforce.

2 Methods

A job task analysis of the physically demanding tasks was undertaken for 27 of the most physically demanding trades (Table 1) within the RAAF. We followed the methodology identified previously [7] which is in alignment with internationally recognised best practice [10, 24]. Accordingly, this study reported on the following key stages: 1) Task identification, 2) Task quantification and characterisation, 3) Task verification and selection of criterion tasks, and 4) Clustering jobs across job functions.

2.1 Participants

636 full-time Australian RAAF personnel participated in this investigation (Table 2), 18% of whom were female which is below the 25% for the active-duty workforce. Participants provided written informed consent before the commencement of the experimental protocol, with ethical approval for the investigation provided by the Australian Defence Human Research Ethics Committee (Protocol 491-07).

Table 1
27 RAAF trades and criterion task representation per cluster

Lift to platform Lift-carry-lower Lift-carry-lift Push / Pull Lift and hold Drag Load carriage Dig / Hammer Lift to anatomical height (without carry) Seated lift Swimming

Aeronautical life support fitter X X X X

Aircraft technician X X X X

Aircraft structures technician X X

Aircraft surface finisher X X X

Armament – EOD technician X X X X X

Avionics technician X X X X

Combat controller X X X X X

Communications electronic technician X X X X

Cook X X

Crew attendant X X X X

Firefighter X X X

Ground mechanical engineer X X X

Ground support equipment X X X

Loadmaster X X X

Medical office, nursing officer, medical technician X X X X

Military working dog handler X X

Movements X X X

Non-destructive inspection technician X X X

Supply X

Airfield engineer X X X

Carpenter X X X

Electrician X X X X X

Plant operator X X

Plumber X X X X

Work supervisor X X

	Lift to platform	Lift-carry-lower	Lift-carry-lift	Push / Pull	Lift and hold	Drag	Load carriage	Dig / Hammer	Lift to anatomical height (without carry)	Seated lift	Swimming
Aeronautical life support fitter	X	X	X	X
Aircraft technician	X			X	X					X
Aircraft structures technician		X			X
Aircraft surface finisher	X		X	X
Armament – EOD technician	X	X	X			X	X
Avionics technician	X		X		X	X
Combat controller		X				X	X	X			X
Communications electronic technician	X	X	X	X
Cook	X		X
Crew attendant	X	X		X		X
Firefighter	X				X	X
Ground mechanical engineer	X	X		X
Ground support equipment	X	X			X
Loadmaster	X	X		X
Medical office, nursing officer, medical technician	X	X	X				X
Military working dog handler	X						X
Movements	X	X		X
Non-destructive inspection technician	X	X			X
Supply	X
Airfield engineer	X		X	X
Carpenter	X	X						X
Electrician	X	X	X		X				X
Plant operator	X		X
Plumber	X	X	X	X
Work supervisor					X	X

Table 2

Participant demographics/characteristics

	Task	Task quantification and	Task verification
	identification	and characterisation	selection of criterion tasks
Total participants	169	298	169
Male (%)	146 (86%)	252 (85%)	124 (73%)
Female (%)	23 (14%)	46 (15%)	45 (27%)
Age (years)	36.0±9.2	32.2±8.4	35.0±9.6
RAAF time in service (years)	12.5±8.4	8.6±6.7	11.9±9.1
Stature (cm)	NA	177.2±8.8	NA
Body mass (kg)	NA	83.4±14.1	NA
Push-ups	NA	29.2±13.2	NA
Sit-ups	NA	74.9±25.0	NA
Estimated VO₂_max (mL.kg^- 1.min^- 1)	NA	40.3±6.8	NA

Note: Data are presented as mean±standard deviation, NA not applicable.

2.2 Task identification

Initial task lists for each trade were developed by reviewing employment profile manuals and then conducting task workshops with each trade. At least one workshop was conducted with each trade, with workshops run by experienced members of the research team. Air Force trade experts (mean n = 6) of a range of rank and roles attended each workshop, during which they were asked to identify and describe the physically demanding tasks performed in the course of their occupational duties. At the conclusion of each workshop, each group of trade experts confirmed that the formulated list of tasks was inclusive of all trade-specific tasks with a perceived high physical demand. For the 27 trades in the RAAF that underwent review, 28 task workshops were conducted, with 169 Air Force personnel involved, across six locations, and 418 physically demanding tasks identified.

2.3 Task quantification and characterisation

Field observations of each trade were conducted with the purpose of objectively quantifying the physical and physiological demands of the tasks identified in the task identification stage. A total of 39 field observations were conducted, with 298 Air Force personnel involved, across 11 locations, and 437 physically demanding tasks quantified. Air Force personnel performed the tasks under typical work practices in the field and/or barracks as an actual task, simulation thereof, or a combination of both. Experienced senior personnel verified that the task scenarios appropriately represented the task to an acceptable standard. The qualified personnel performing these task were all medically fit for duty and were encouraged to identify any other physically demanding tasks not recognised during the initial task identification. All tasks were conducted wearing the most appropriate military clothing and equipment for that task.

To profile personnel fitness levels, a baseline testing session was conducted that included a push-up test, sit-up test (maximum 100), and 20 m multi-stage shuttle run to exhaustion, with at least 2 minutes rest between each test, with the session completed within 30 minutes. To characterise the physiological demands of the tasks, heart rate (Polar Team 2, Polar Electro Inc, Finland), oxygen consumption (VO₂; Metamax 3B, Cortex, Leipzig, Germany) and rating of perceived exertion (RPE) using the 15-point (6–20) Borg scale [25] data were collected. Heart rate and VO₂ were recorded continuously and reported as a mean for the task duration, and RPE was collected as soon as possible following task completion. Heart rate and VO₂ were only collected for tasks exceeding 2 minutes in duration and cardiorespiratory demands were subjectively considered to be at least moderate. Movement speeds, distances and durations were collected via a global-positioning system (GPS; Optimeye S5; Catapult Sports Pty Ltd., Melbourne, Australia) sampled at 10 Hz. To determine task parameters, the mass of items carried and/or lifted was measured using either platform scales (PM150, Wedderburn, New South Wales, Australia) or a portable force plate (400 Series Force Plate, Fitness Technology, Adelaide, South Australia, Australia). Distances and heights were measured using a tape measure and pushing / pulling forces were measured using an inline force sensor (Noraxon TeleMyo DTS, Arizona, USA) with a sampling frequency of 1500 Hz. Task durations were determined using either a stop watch, GPS, or video camera. Working postures, carry and lifting positions, number of personnel involved, repetitions, number of hands used, asymmetry of the task, ground stability/surface type, and actions used were noted by the research team.

2.4 Task verification and selection of criterion tasks

Subsequent to task quantification and characterisation, follow-up focus groups with a group of Air Force trade experts of a range of ranks and experience were conducted for each trade in the same manner as the initial task identification workshops. A total of 26 task confirmation workshops were conducted, with 169 Air Force personnel involved, across 5 locations, 408 physically demanding tasks confirmed, and 87 criterion tasks identified. Researchers presented the outcomes of the task quantification and characterisation stage, with Air Force personnel asked to 1) confirm and endorse the physically demanding task list and descriptions, 2) confirm task parameters and 3) select criterion tasks. Air Force personnel were able to identify differences between work practices observed during the observations and expected methods, allowing tasks to be updated accordingly and re-quantified where necessary. Tasks were presented and grouped together based on the dominant physical capacity or capacities required to successfully complete the task, determined using both objective data and expert opinion by the PES research team [7]. The four dominant physical capacities were: a) Cardiorespiratory endurance: Tasks that may typically be described as dynamic whole-body efforts performed at a moderate-to-high intensity for a sustained period, e.g. a forced march or configuring/rigging an aircraft; b) High intensity: Tasks that may be typically described as dynamic whole-body efforts performed at a high intensity for a short period, e.g. moving tactically whilst engaged (i.e., fire and movement) or moving to points of cover; c) Muscular strength: Tasks that require a specific muscle or muscle groups to generate an absolute force for successful task completion, e.g. lifting heavy items to a shelf, workbench or vehicle; and d) Muscular endurance: Tasks that require the execution of repeated or sustained contractions of specific/isolated muscles for a prolonged period, e.g. performing a casualty stretcher carry or unloading and carrying stores.

The selection of criterion tasks was based on two key criteria 1) the task was more physically demanding relative to others that were classified in the same physical capacity or attribute group, a researcher-led decision (based from the objective data collected during observations) and 2) all members within the trade were expected to be able to safety and successfully execute the task, a trade experts-led decision [7].

2.5 Clustering jobs across job functions and data analysis

To better understand the criterion tasks, these were also categorised into movement clusters based on movement patterns and actions [7]. This cluster categorisation was independent of the dominant physical capacity categorisation. Clusters were lift to platform, lift to an anatomical height (without carry), lift & hold, seated lift, lift and twist, lift-carry-lift, lift-carry-lower, drag, push / pull, dig / hammer, load carriage, and swimming. Load carriage tasks involved sustained locomotion with a torso-borne load, whereas swimming tasks were tasks involving any swimming. Descriptions of all other clusters have been previously reported [7]. For some tasks, certain data could not be collected due to task complexity or other logistical constraints. In such instances, data were omitted.

The number of tasks and the proportion (%) of tasks were calculated for each task cluster, and physical fitness attribute. Descriptive statistics were calculated for task characteristics and physiological demands; median [25^th–75th percentile], these data were non-normally distributed as assessed by visual inspection. All analysis were performed in Microsoft Excel (version 2016, Redmond, USA).

3 Results

An initial 418 tasks were identified during the task identification stage, which increased to 437 tasks following the task quantification and characterisation stage, with 408 tasks at the conclusion of the task verification workshops. Ultimately 87 criterion tasks were selected. Muscular strength was deemed to be the ‘dominant’ or ‘equally dominant’ physical capacity in 51 (59%) criterion tasks, followed by muscular endurance in 45 (52%), cardiorespiratory endurance in 34 (39%), high intensity in two (2%), while 35 (40%) spanned multiple physical capacities (Table 3). Manual handling criterion tasks were the most prevalent, comprising 80 (92%) of the 87 criterion tasks, while the remaining seven criterion tasks involved load carriage in six (7%) and swimming in one (1%). As presented in (Table 3) the most common movement clusters were the lift to platform, and lift and carry (lift-carry-lower and lift-carry-lift).

Table 3
Cluster allocation of criterion tasks and physical capacity

Cluster Number of tasks % of tasks Physical capacity

Muscular strength Muscular endurance Cardiorespiratory endurance

Lift to platform 38 44% 32 16 8

Lift-carry-lower 20 23% 11 17 12

Lift-carry-lift 13 15% 11 7 3

Push / Pull 11 13% 7 6 5

Lift and hold 11 13% 2 8 4

Drag 8 9% 6 4 4

Load carriage 8 9% 2 1 7

Dig / Hammer 3 3% 2 2 2

Lift to anatomical height (without carry) 1 1% 0 1 0

Seated lift 1 1% 0 1 0

Swimming 1 1% 0 0 1

1 cluster 59 68% – – –

2 clusters 25 29% – – –

3 clusters 2 2% – – –

Cluster	Number of tasks	% of tasks	Physical capacity
Lift to platform	38	44%	32	16	8
Lift-carry-lower	20	23%	11	17	12
Lift-carry-lift	13	15%	11	7	3
Push / Pull	11	13%	7	6	5
Lift and hold	11	13%	2	8	4
Drag	8	9%	6	4	4
Load carriage	8	9%	2	1	7
Dig / Hammer	3	3%	2	2	2
Lift to anatomical height (without carry)	1	1%	0	1	0
Seated lift	1	1%	0	1	0
Swimming	1	1%	0	0	1
1 cluster	59	68%	–	–	–
2 clusters	25	29%	–	–	–
3 clusters	2	2%	–	–	–

3.1 Lift to platform

All lift to platform tasks required lifting from the ground to a median height of 1.32 m [1.20 –1.65 m] and handling a median mass of 25.0 kg [21.0 –28.9 kg] per person. Twenty-four (63%) of the lifts were performed individually, 12 (32%) were two-person lifts and two (5%) were lifted in a team of four. All lift to platform tasks involved a deadlift action (item lifted from below 0.7 m), 36 (95%) an upright row action (item lift height 0.7 to 1.35 m from ground), and 17 (45%) involved a vertical lift (item lift height above 1.35 m from ground) approaching shoulder height or above. The median number of lifts was 1 repetition [1 –6 repetitions], with 20 tasks (53%) involving a single discrete lift, 11 tasks (29%) requiring between 2 and 9 repetitions, while seven tasks (18%) involved 10 or more repetitions.

3.2 Lift and carry tasks

Collectively, the lift and carry tasks (lift-carry-lift and lift-carry-lower) median mass was 25.0 kg [22.4 –36.1 kg] per person and the median carry distance was 26 m [18 –50 m] (Table 4). Eighteen (56%) of the carries were performed individually, 10 (31%) were two-person carries and four (13%) were carried in a team of four. Twelve (44%) of the carry tasks involved a single discrete carry, 11 (41%) tasks were between 2 and 9 repetitions, while four (15%) involved 10 or more carries. Nineteen (59%) of the carry tasks were performed bilaterally, while 13 (41%) carry tasks were performed unilaterally.

Table 4
Criterion carry characteristics

All Lift-carry-lower Lift-carry-lift Bilateral Unilateral

Mass (kg) per person 25.0 [22.4 – 36.1] 23.0 [19.5 – 28.6] 29.6 [25.0 – 40.0] 29.6 [25.0 – 40.0] 22.5 [19.0 – 25.0]

Distance (m) per carry 26 [18 – 50] 40 [20 – 90] 20 [10 – 30] 20 [13 – 30] 65 [44 – 120]

Carry repetitions 2 [1 – 6] 3 [1 – 6] 1 [1 – 8] 4 [1 – 6] 1 [1 – 4]

Total carry distance (m) 100 [46 – 195] 110 [95 – 233] 80 [20 – 100] 100 [20 – 200] 100 [80 – 180]

	All	Lift-carry-lower	Lift-carry-lift	Bilateral	Unilateral
Mass (kg) per person	25.0 [22.4 – 36.1]	23.0 [19.5 – 28.6]	29.6 [25.0 – 40.0]	29.6 [25.0 – 40.0]	22.5 [19.0 – 25.0]
Distance (m) per carry	26 [18 – 50]	40 [20 – 90]	20 [10 – 30]	20 [13 – 30]	65 [44 – 120]
Carry repetitions	2 [1 – 6]	3 [1 – 6]	1 [1 – 8]	4 [1 – 6]	1 [1 – 4]
Total carry distance (m)	100 [46 – 195]	110 [95 – 233]	80 [20 – 100]	100 [20 – 200]	100 [80 – 180]

Data are median [25th – 75th percentile]. Total carry distance is distance per carry×repetitions.

3.3 Other tasks (push/pull, lift and hold, drag)

Six of the 11 push/pull tasks were performed while stationary, with four of these performing repeated actions, three of which were whole body movements. The other two stationary push/pull tasks were a single whole-body pulling effort. From the other push/pull tasks, four involved continuous locomotion, during which items on wheels or rollers were moved 10 to 120 m.

Six of the 11 lift and hold tasks involved holding items with a mass of 2 kg or less. Further, six holding tasks were performed in awkward postures, five tasks were performed with outstretched arms, five tasks were performed overhead, and five of the tasks were performed over extended durations (30 min –8 hours) often involving repeated efforts (5 –10 min) throughout a work day.

Four of the eight dragging tasks involved dragging a casualty, three of which required the rescuer to wear an external load (8 –26 kg). Two casualty drags were performed individually (86 –95 kg casualty mass) over 8 to 30 m, while the other two casualty drags were performed in pairs (108 –118.5 kg casualty mass) over 20 to 30 m. Of the non-casualty dragging tasks, three were dragging hoses and/or cords of distances up to 30 m, and one task involved dragging various items across the sand over 100 to 300 m.

3.4 Physiological and perceptual demands

Physiological and perceptual demands were measured for 31 of the criterion tasks, involving 220 personnel across 17 trades. Across all measured tasks Vdot;O₂, heart rate and RPE were 1.8 L·min^- 1 [1.5 –2.2 L·min^- 1], 137 b·min^- 1 [120 –144 b·min^- 1] and 13 [somewhat hard; 12 –14] respectively (Table 5). Nineteen tasks (61%) elicited a VO₂ of between 1.5 –2.4 L·min^- 1 (Table 5).

Fourteen tasks (45%) from 10 trades involved repeated manual handling (i.e., tasks involving multiple lifts / carries). The median number of items handled was 14 [6 –22], while the median carry distance was 20 m [10 –30 m], with all 14 tasks involving handling items≥22.0 kg. The median VO₂, heart rate and RPE for these repeated manual handling tasks was 2.0 L·min^- 1 [1.7 –2.1 L·min^- 1], 136 b.min^- 1 [121 –144 b·min^- 1] and 14 [Somewhat hard to Hard; 13–14] respectively (Table 5). Nine tasks (65%) elicited a VO₂ of between 1.5 –2.4 L·min^- 1.

From the eight criterion tasks involving load carriage (Table 3), the physiological demands of six tasks were measured. The median VO₂, heart rate and RPE for these tasks was 2.3 L·min^- 1 [2.1 –2.4 L·min- 1], 141 b·min^- 1 [136 –147 b·min^- 1] and 12 [Light to Somewhat hard; 12–13] respectively, with five tasks (83%) eliciting a VO₂ between 1.5 –2.4 L·min^- 1 (Table 5).

Table 5
Summary of physiological and perceptual demands for measured criterion tasks

Measure All criterion tasks Repeated manual handling tasks Load carriage tasks

No. of tasks 31 14 6

No. of trades 17 10 3

No. of RAAF personnel 220 120 61

Duration (min:sec) 9:12 [7:30 –24:36] 9:41 [7:47 –13:37] 10:42 [8:42 –22:00]

VO₂ (L·min^- 1) 1.8 [1.5–2.2] 2.0 [1.7–2.1] 2.3 [2.1–2.4]

Tasks < 1.5 L·min^- 1 26% (8/31) 14% (2/14) 0% (0/6)

Tasks 1.5–1.9 L·min^- 1 29% (9/31) 29% (4/14) 17% (1/6)

Tasks 2.0–2.4 L·min^- 1 32% (10/31) 36% (5/14) 66% (4/6)

Tasks≥2.5 L·min^- 1 13% (4/31) 21% (3/14) 17% (1/6)

HR (b.min^- 1) 137 [120–144] 136 [121–144] 141 [136–147]

RPE 13 [12 –14] 14 [13–14] 12 [12–13]

Measure	All criterion tasks	Repeated manual handling tasks	Load carriage tasks
No. of tasks	31	14	6
No. of trades	17	10	3
No. of RAAF personnel	220	120	61
Duration (min:sec)	9:12 [7:30 –24:36]	9:41 [7:47 –13:37]	10:42 [8:42 –22:00]
VO₂ (L·min^- 1)	1.8 [1.5–2.2]	2.0 [1.7–2.1]	2.3 [2.1–2.4]
Tasks < 1.5 L·min^- 1	26% (8/31)	14% (2/14)	0% (0/6)
Tasks 1.5–1.9 L·min^- 1	29% (9/31)	29% (4/14)	17% (1/6)
Tasks 2.0–2.4 L·min^- 1	32% (10/31)	36% (5/14)	66% (4/6)
Tasks≥2.5 L·min^- 1	13% (4/31)	21% (3/14)	17% (1/6)
HR (b.min^- 1)	137 [120–144]	136 [121–144]	141 [136–147]
RPE	13 [12 –14]	14 [13–14]	12 [12–13]

Data are median [25^th –75^th percentile].

4 Discussion

This study characterised and quantified 87 physically demanding criterion tasks identified from 27 of the most physically demanding trades within the RAAF. The analysis has revealed substantial commonality among the tasks performed by Air Force personnel (Table 1). The majority of the criterion tasks required manual handling, reinforcing the importance that personnel have sufficient requisite muscular strength and endurance to perform the task safely. Of these tasks, lifting to a platform and lift and carry were the predominate movement clusters identified. Repeated manual handing tasks were frequent across the trades. Cardiorespiratory demands were moderate in the tasks requiring this capacity. Understanding these physical demands allows for the development of informed PES as well as conditioning programs to match the job fitness requirements across the RAAF.

We believe this is the first study to provide in-depth results of organisation-wide critical and physically demanding job task analysis of an Air Force. Lifting to a platform was the most common type of criterion task as many tasks require items being loaded to workbenches, vehicle trays or various aircraft storage locations. Importantly the vertical height of the platform could not be adjusted, thus whole-body lifting to an absolute (e.g., 1.3 m) rather than a relative height (e.g., shoulder height) is a critical requirement for RAAF personnel. Only, one criterion task was identified that required RAAF personnel to complete the lift at an anatomical landmark (i.e. an electrician lifting to overhead during the installation of lights). The mass required to be lifted for the critical demanding tasks was consistently above the maximum mass limits recommended by the NIOSH equation, which start at 23 kg for a lift under ideal conditions and then reduces as variables such as height of the lift increase [26].

Manual material handling tasks have been identified as one of the most common causes of injury during military deployment, with repetitive lifting and lifting height related to injury [27]. These findings emphasise the importance of valid physical assessments and specific physical training protocols to ensure personnel have the necessary physical attributes to meet the physical demands of these critical tasks. Assessments of physical performance must therefore be correlated with performance of the criterion tasks [10]. However current field-based physical assessment practices, which have a strong historical precedent in military organisations, often provide limited insight into the performance of critical physically demanding tasks. For example, it is likely that the current push-up assessment adopted by the RAAF is a poor predictor of job task performance of lift to platform tasks based on previous findings, where push-ups were not significantly (p > 0.05) related to lift and place performance, with less than 5% of the variance explained (R² < 0.05) [2, 5]. It is probable that a scalable lift to fixed height assessment, such as the task-related predictive box lift and place test developed for the Australian Army [2 , 28–33], that has strong (R² 0.36 –0.76) relationships to military lifting tasks [2], would be a superior protocol to assess muscular strength to a relevant absolute height than push-ups, which is a test of muscular endurance.

Although, we observed most lifts performed in RAAF are to fixed vertical heights (interquartile range 1.20 –1.65 m), anatomical lifting assessments have been preferred by some organisations, either to improve correlation with relative job task demands or to acknowledge possible accommodation strategies (a step) thus removing potential bias in personnel of differing stature. Accommodation strategies must also include the provision of appropriate physically conditioning regimen to ensure personnel have developed sufficient physical capacities to perform critical physical demanding tasks safely. Beck et al. [33] demonstrated that when normalised for lean mass, neither stature or sex had an effect on lift performance on a 1.3 –1.5 m box lift and place assessment, suggesting perceived limitations of stature and sex can be overcome when personnel are exposed to an appropriate strength training regimen. Further, a box lift and place assessment to an absolute height would have greater content validity than an anatomical lift (relative height) assessment and is predictive of performance across a range of heights (1.3 –1.7 m) that are performed by RAAF [30]. Although, cut-scores may differ, the implementation of a common lifting assessment standard across both the RAAF and the Australian Army would have several potential benefits including the standardising of recruitment assessments, conditioning and equipment while retaining validity. An example of this is the Canadian Armed Forces, who have implemented a universality of service PES, where personnel across the three services perform the same PES assessments [10].

Lifting and carrying an object in the hand/s was the next most prevalent criterion tasks recorded across the RAAF, with the item masses similar to those in the lift to platform task cluster. We observed the carry phase of the lift and carry task consisted of a mix of bilateral and unilateral carries performed either as a team or individually. Bilateral carries were usually (74%) associated with repetitive loading tasks (such as loading an aircraft) involving equal distance moved with and without load. In contrast, unilateral carry tasks (such as a four-person stretcher carry or two-person item carry) more often (54%) required longer single effort carries. As with lift to platform tasks, the current push-up assessment has been demonstrated to be a poor predictor of repeated lift and carry tasks within the Australian Army [2]. It is again likely that the muscular endurance assessment developed for the Australian Army — a scalable bilateral jerry can carry [34 –36] — which predicts performance in a unilateral stretcher carry [35, 36], could be adapted and utilised for the RAAF. The Army bilateral assessment was developed to assess individual performance in a team task requiring a unilateral effort (stretcher carry), with a bilateral assessment preferred for safety reasons. Although a unilateral carry assessment more closely simulates the stretcher carry task, unilateral carries have been shown to increase spinal compressive and shear forces compared to bilateral carries of twice the same mass [37]. The job tasks analysis revealed that RAAF perform a range of unilateral and bilateral carry criterion tasks; therefore, we suggest implementing a bilateral assessment for safety reasons, but including both bilateral and some degree of unilateral carries during physical training to condition the body to the job task demands. These movements are currently not assessed by RAAF physical assessment protocols.

The majority of criterion tasks where cardiorespiratory endurance was deemed a dominant physical capacity required a moderate cardiorespiratory demand (Table 5), notably with almost half (44%) of tasks involving repeated manual handling. There were only eight load carriage tasks which spanned five of the 27 trades analysed. Cardiorespiratory endurance capacity of Army personnel is assessed via a loaded march PES test across many western military forces [10]. However, a load carriage assessment would likely not be suitable for RAAF as this only represents (9%) of all criterion tasks. Additionally, torso-borne loads apply unique stress to the cardiorespiratory and muscular systems that only a small proportion of RAAF personnel are required to withstand [38]. The RAAF have currently adopted an unloaded running assessment (i.e. 2.4-km run). However, this does not capture the repetitive manual handing demands of several criterion tasks. We suggest it is possible to address both the cardiorespiratory and muscular endurance requirements with a single repetitive carry assessment. Repeated carry assessments are widely utilised in military PES with Australia, Canada, U.K., New Zealand, and the Netherlands requiring personnel to repeatedly carry items such as jerry cans, sandbags or boxes [10]. While repetitive carry protocols are often employed to assess muscular endurance capacity, they can simultaneously stress — and therefore could effectively assess — cardiorespiratory capacity [35, 36], particularly if lift and carry parameters are scaled to match the job task requirements.

Previously reported British Air Force PES demands [13 , 16] have differed to the RAAF physical demands observed within this investigation. British RAF Regiment physical performance requirements appear to exceed the physical demands we identified for RAAF personnel. For example, RAF regiment personnel perform heavier and higher lifts (30 kg and 1.6 m, respectively), longer lift-carry-lower tasks (stretcher carry; 1 km), longer load carriage tasks (16 km), heavier individual drags (111 kg), as well as performing other tasks not common among RAAF personnel [13]. However, the generic core British RAF task demands generally required a lower performance standard. Like the RAAF, the generic British RAF tasks are predominately manual handling, although with a lighter mass, commonly less than 10 kg [16]. Lift heights and carry distances are comparable with RAAF, typically 1.0 –1.5 m and 10 –51 m, respectively [16]. However, cardiorespiratory demands were lower than for RAAF, with VO₂ values of 1.0 –1.5 L·min^- 1 recorded [16].

The outcomes of the RAAF job task analysis align closely with the Australian Army PES task analysis [7 , 40] and British Army PES task analysis [41], that identified a high prevalence of manual handling tasks. Lifting then carrying were the most prevalent actions performed in both armies [7, 41]. The RAAF lift to platform masses and heights were generally consistent with those of both the Australian Army (25.6±8.5 kg; 1.41±0.19 m; [39]) and British Army (20–29 kg; 1.0 –1.5 m; [41]). Compared with the RAAF, lift-carry-lower tasks were heavier and further per effort in the Australian Army (31.3±17.1 kg, 127.8±126.2 m), while lift-carry-lift tasks were similar (29.2±9.0 kg; 16.3±8.8 m; [39]). Cardiorespiratory demands were similar between the RAAF and the British Army, with VO₂ values between 1.5 and 2.5 L·min^- 1 [41]. Load carriage differed considerably between the RAAF and Army, with load carriage a niche requirement within the RAAF while marching is a fundamental expectation of all Army personnel. These similarities and differences across military groups and nations highlight the importance of performing separate job task analysis for the workplace of interest, to determine the nuances of the physical requirements, so that valid assessments and defensible cut-scores can be implemented.

There are challenges when characterising so many RAAF trades that are spread across the country. At times the depth of engagement with each trade was suboptimal compared to just assessing one trade, due to logistical constraints, small trade numbers and operational tempo. Large scale surveys are often utilised in PES as a means to help with task identification and the down-selection process of the most physically demanding tasks [10]. Surveys were not performed in this investigation, but they could have allowed for data collection across a broader population of the RAAF than assessed in this job task analysis and given more confidence in the tasks selected. Our multi-step approach does however provide multiple opportunities for tasks to be identified and quantified giving confidence of the selection of appropriate criterion tasks. Another consideration is that some trades are highly specialised and have low personnel levels, sometimes only one member at a base, which may have skewed results when collecting physiological measures. In these instances, we tried to collect data from as many locations as possible.

5 Conclusion

This RAAF job task analysis revealed that 92% of criterion tasks, for the 27 trades investigated, were manual handling. Lifting to a platform and carry tasks were the predominant movement clusters identified. The high proportion of criterion tasks classified as manual handling underscores the importance of these activities and the underlying physical capacities (muscular strength as well as muscular and cardiorespiratory endurance) for RAAF personnel, irrespective of trade. Cardiorespiratory demands were moderate of the tasks requiring this capacity. The results also suggest the current generic fitness assessments are unlikely to be predicting job task performance. There is potential to replace the current assessments with a limited suite of scalable task-related predictive PES tests, such as a lift and place assessment and repeated carry assessment. Characterisation of these occupational physical task demands permits the development of physical standards, the setting of defensible cut-scores and providing a focus for physical conditioning programs, thus ultimately improving the alignment with workforce capability and occupational demands.

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical Approval

Ethical approval for the investigation was provided by the Australian Defence Human Research Ethics Committee (Protocol 491-07).

Informed consent

Participants provided written informed consent before the commencement of the experimental protocol.

Footnotes

Acknowledgments

The authors would like to acknowledge and thank the staff at Defence Science and Technology Group and the University of Wollongong who assisted with the RAAF PES project. Additionally, RAAF liaison officers WGCDR Marcelle Mitting and SQNLDR Andrew Miller for coordinating workshops and field observations. Lastly, all the RAAF personnel who contributed to the PES project.

Funding

Not applicable.

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