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

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.

Exoskeleton Application to Military Manual Handling Tasks.

OBJECTIVE: The aim of this review was to determine how exoskeletons could assist Australian Defence Force personnel with manual handling tasks. BACKGROUND: Musculoskeletal injuries due to manual handling are physically damaging to personnel and financially costly to the Australian Defence Force. Exoskeletons may minimize injury risk by supporting, augmenting, and/or amplifying the user's physical abilities. Exoskeletons are therefore of interest in determining how they could support the unique needs of military manual handling personnel. METHOD: Industrial and military exoskeleton studies from 1990 to 2019 were identified in the literature. This included 67 unique exoskeletons, for which Information about their current state of development was tabulated. RESULTS: Exoskeleton support of manual handling tasks is largely through squat/deadlift (lower limb) systems (64%), with the proposed use case for these being load carrying (42%) and 78% of exoskeletons being active. Human-exoskeleton analysis was the most prevalent form of evaluation (68%) with reported reductions in back muscle activation of 15%-54%. CONCLUSION: The high frequency of citations of exoskeletons targeting load carrying reflects the need for devices that can support manual handling workers. Exoskeleton evaluation procedures varied across studies making comparisons difficult. The unique considerations for military applications, such as heavy external loads and load asymmetry, suggest that a significant adaptation to current technology or customized military-specific devices would be required for the introduction of exoskeletons into a military setting. APPLICATION: Exoskeletons in the literature and their potential to be adapted for application to military manual handling tasks are presented.

Identifying Physically Demanding Tasks Performed by the Royal Australian Navy for the Development of a Physical Employment Standard.

OBJECTIVE: The aim of this study was to determine an appropriate method to characterize Royal Australian Navy intermittent intensity tasks. METHOD: Sixteen personnel performed four scenarios: (1) storing: repeatedly handle a 10 to 15 kg crate; (2) firefighting: walk 45 m wearing protective equipment and fighting a fire; (3) and (4) toxic hazard response: casualty evacuation tasks wearing protective equipment. Heart rate and oxygen consumption ((Equation is included in full-text article.)) were measured continuously. Mean and peak values and time spent in incremental zones were calculated. RESULTS: Scenario 2 elicited the highest oxygen cost (18.1 L, mean (Equation is included in full-text article.)1.5 L.min, time >2.5 L.min: 0.8%), yet scenario 4 elicited the highest mean (Equation is included in full-text article.)(1.8 L.min, oxygen cost 14.4 L), and participants spent a greater duration >2.5 L.min(Equation is included in full-text article.)(23.3% or 1 minute 55 seconds). CONCLUSIONS: A small difference (0.3 L.min) was observed between scenarios 2 and 4 for mean (Equation is included in full-text article.), yet (Equation is included in full-text article.)>2.5 L.min demonstrated scenario 4 had a higher metabolic demand.

Understanding Anthropometric Characteristics Associated With Performance in Manual Lifting Tasks.

Beck, B, Middleton, KJ, Billing, DC, Caldwell, JN, and Carstairs, GL. Understanding anthropometric characteristics associated with performance in manual lifting tasks. J Strength Cond Res 33(3): 755-761, 2019-Manual lifting is an essential military job task and is commonly linked to occupational injury. Methods to reduce injury risk focus on ensuring that employees have the requisite physical capacity to safely conduct critical job tasks. The aim of this study was to investigate which anthropometric characteristics are associated with lifting performance to inform targeted training programs for job-critical lifting tasks. Sixty-three (42 men and 21 women) participants conducted 3 maximal lifts to a platform (pack lift to 1.5 m, box lift to 1.3 m and box lift to 1.5 m). A dual-energy x-ray absorptiometry scan was used to quantify anthropometric characteristics (body region-specific lean mass and fat mass). Although anthropometric measures were strongly associated with each other, multivariable linear regression revealed that a significant proportion of the total variation in lifting performance in each of the 3 tasks was explained by upper-arm lean mass (pack lift: ß = 5.42, p < 0.001; box lift 1.3 m: ß = 5.64, p < 0.001; box lift 1.5 m: ß = 7.00, p < 0.001). Leg lean mass also significantly contributed to the variation of pack lift performance (ß = 0.93, p = 0.01). When controlling for key anthropometric characteristics in these 3 tasks, separate analyses showed no significant effect of sex or stature on lift performance. These results suggest that the perceived limitations of stature and sex may be overcome by targeted training programs to improve specific physical characteristics associated with lifting performance.

A method for developing organisation-wide manual handling based physical employment standards in a military context.

The benefit of job-related employment standards in physically demanding occupations are well known. A number of methodological frameworks have been established to guide the development of physical employment standards for single job functions. In the case of an organisation comprised of multiple and diverse employment specialisations, such as the Australian Army, it is impractical to develop unique employment standards for each occupation. OBJECTIVES: To present an approach to organisational level physical employment standards development that seeks to retain occupationally specific task characteristics by applying a movement cluster approach. DESIGN: Structured methodological overview. METHODS: An outline of the research process used in performing job tasks analysis are presented, including the identification, quantification and characterisation, and verification of physically demanding manual handling tasks. The methodology used to filter task information collected from this job analyses to group manual handling tasks with similar characteristics (termed clusters), across a range of employment specialisations is given. Finally, we provide examples of test development based on these key manual handling clusters to develop a limited suite of tests with high content, criterion and face validity that may be implementable across a large organisation. RESULTS: Job task analysis was performed on 57 employment specialisations, identifying 458 tasks that were grouped into 10 movement based clusters. The rationalisation of criterion tasks through clustering informed the development of a limited suite of tests with high content, criterion and face validity that may be implementable across a large organisation. CONCLUSION: This approach could be applied when developing physical employment standards across other multi-occupation organisations.

The sensitivity of a military-based occupational fitness test of muscular strength.

The risk of low back pain and injury during manual materials handling is increased if personnel are not physically capable of safely performing such tasks. To establish predictive relationships and develop a test cut-score, 69 participants performed a critical military lifting task to a 1.5-m platform (pack lift) and two task-related predictive tests (box lift to 1.5 m and 1.3 m). The pack lift was strongly correlated with both the 1.5-m (R2 = 0.85) and 1.3-m box lifts (R2 = 0.82). Both tests had similar sensitivity (range 0.85-0.94) with the 1.3-m test having higher specificity when compared with the 1.5-m lift. Increasing the test cut-score with the application of a safety factor increased the number of false positives and true negatives for both tests. Organisations must carefully assess their risk acceptance when applying safety factors to test cut-scores as the classification (pass/fail) of personnel may be affected.

Modifiable Anthropometric Characteristics Are Associated With Unilateral and Bilateral Carry Performance.

Beck, B, Carstairs, GL, Billing, DC, Caldwell, JN, and Middleton, KJ. Modifiable anthropometric characteristics are associated with unilateral and bilateral carry performance. J Strength Cond Res 31(2): 489-494, 2017-A mismatch between physical ability and task requirements can increase the risk of on-the-job injury. Therefore, understanding key anthropometric characteristics associated with job performance is important in developing targeted training programs and selecting employees in physically demanding occupations. The aims of this study were to understand which anthropometric and demographic (age/sex) characteristics were associated with performance in a unilateral stretcher carry and bilateral jerry can and kettle bell carries. Sixty-seven enlisted Australian Army soldiers (46 men and 21 women) participated in this investigation. Body composition was quantified using dual-energy X-ray absorptiometry. Univariate and multivariable regression techniques were used to quantify correlations between anthropometric characteristics and carry performance. Median carry distance was 650 m (interquartile range [IQR] = 425-1,025 m) in the stretcher carry, 300 m (IQR = 215-445 m) in the jerry can carry, and 265 m (IQR = 200-400 m) in the kettle bell carry. Univariate analyses demonstrated that whole body, trunk, upper arm, forearm, and leg lean mass, as well as stature and body mass were associated with performance across the 3 carry tasks. Of these, leg lean mass was shown to be a key characteristic associated with carry performance. Subsequently, it is suggested that training programs focus on whole-body lean mass with specific emphasis on leg lean mass. Additionally, we demonstrated that age and sex were not significantly associated with carry performance when controlling for leg lean mass, indicating that modifiable factors can be targeted in training programs to improve job performance.

The application of subjective job task analysis techniques in physically demanding occupations: evidence for the presence of self-serving bias.

The aim of this study was to determine if perceptions of physically demanding job tasks are biased by employee demographics and employment profile characteristics including: age, sex, experience, length of tenure, rank and if they completed or supervised a task. Surveys were administered to 427 Royal Australian Navy personnel who characterised 33 tasks in terms of physical effort, importance, frequency, duration and vertical/horizontal distance travelled. Results showed no evidence of bias resulting from participant characteristics, however participants who were actively involved in both task participation and supervision rated these tasks as more important than those involved only in the supervision of that task. This may indicate self-serving bias in which participants that are more actively involved in a task had an inflated perception of that task's importance. These results have important implications for the conduct of job task analyses, especially the use of subjective methodologies in the development of scientifically defensible physical employment standards. Practitioner Summary: To examine the presence of systematic bias in subjective job task analysis methodologies, a survey was conducted on a sample of Royal Australian Navy personnel. The relationship between job task descriptions and participant's demographic and job profile characteristics revealed the presence of self-serving bias affecting perceptions of task importance.

Predicting Endurance Time in a Repetitive Lift and Carry Task Using Linear Mixed Models.

OBJECTIVES: Repetitive manual handling tasks account for a substantial portion of work-related injuries. However, few studies report endurance time in repetitive manual handling tasks. Consequently, there is little guidance to inform expected work time for repetitive manual handling tasks. We aimed to investigate endurance time and oxygen consumption of a repetitive lift and carry task using linear mixed models. METHODS: Fourteen male soldiers (age 22.4 ± 4.5 yrs, height 1.78 ± 0.04 m, body mass 76.3 ± 10.1 kg) conducted four assessment sessions that consisted of one maximal box lifting session and three lift and carry sessions. The relationships between carry mass (range 17.5-37.5 kg) and the duration of carry, and carry mass and oxygen consumption, were assessed using linear mixed models with random effects to account for between-subject variation. RESULTS: Results demonstrated that endurance time was inversely associated with carry mass (R2 = 0.24), with significant individual-level variation (R2 = 0.85). Normalising carry mass to performance in a maximal box lifting test improved the prediction of endurance time (R2 = 0.40). Oxygen consumption presented relative to total mass (body mass, external load and carried mass) was not significantly related to lift and carry mass (ß1 = 0.16, SE = 0.10, 95%CI: -0.04, 0.36, p = 0.12), indicating that there was no change in oxygen consumption relative to total mass with increasing lift and carry mass. CONCLUSION: Practically, these data can be used to guide work-rest schedules and provide insight into methods assessing the physical capacity of workers conducting repetitive manual handling tasks.

A Box Lift and Place Assessment is Related to Performance of Several Military Manual Handling Tasks.

Soldiers undergo regular physical testing to assess their functional capacity. However, current physical tests, such as push-ups, sit-ups, and pull-ups, do not necessarily assess job-specific physical capability. This article assesses the utility of generic predictive tests and a task-related predictive test in predicting performance against four job-critical military manual handling tasks. The box lift and place test was found to be the superior predictor in performance of four job tasks; a pack lift and place (R(2) = 0.76), artillery gunner loading simulation (R(2) = 0.36), bombing up an M1 tank simulation, (R(2) = 0.47) and a bridge building simulation (R(2) = 0.63). Pull-ups and push-ups were poor predictors of performance in the majority of job tasks. Although the box lift and place had a larger correlation with the artillery gunner loading task than the generic assessment, it only accounted for 36% of the variance, indicating that a task simulation may be more appropriate to assess soldiers' capacity to perform this job task. These results support the use of a box lift and place rather than generic fitness tests for the evaluation of military manual handling tasks.

Predicting stretcher carriage: Investigating variations in bilateral carry tests.

Carrying a casualty on a stretcher is a critical task within military and emergency service occupations. This study evaluated the impact of manipulating carry speed and the object type in bilateral carries on the ability to predict performance and reflect the physical and physiological requirements of a unilateral stretcher carry. We demonstrated that three task-related predictive tests; a jerry can carry performed at 4.5 km h(-1)or 5.0 km h(-1) and a kettle-bell carry performed at 5.0 km h(-1) were strongly predictive of the physical and physiological demands of an individual participating as part of a four-person stretcher carry team. Therefore, bilateral predictive assessments have the utility for predicting the suitability of employees to effectively and safely conduct a four-person unilateral stretcher carry.

Lift performance and lumbar loading in standing and seated lifts.

This study investigated the effect of posture on lifting performance. Twenty-three male soldiers lifted a loaded box onto a platform in standing and seated postures to determine their maximum lift capacity and maximum acceptable lift. Lift performance, trunk kinematics, lumbar loads, anthropometric and strength data were recorded. There was a significant main effect for lift effort but not for posture or the interaction. Effect sizes showed that lumbar compression forces did not differ between postures at lift initiation (Standing 5566.2 ± 627.8 N; Seated 5584.0 ± 16.0) but were higher in the standing posture (4045.7 ± 408.3 N) when compared with the seated posture (3655.8 ± 225.7 N) at lift completion. Anterior shear forces were higher in the standing posture at both lift initiation (Standing 519.4 ± 104.4 N; Seated 224.2 ± 9.4 N) and completion (Standing 183.3 ± 62.5 N; Seated 71.0 ± 24.2 N) and may have been a result of increased trunk flexion and a larger horizontal distance of the mass from the L5-S1 joint. Practitioner Summary: Differences between lift performance and lumbar forces in standing and seated lifts are unclear. Using a with-in subjects repeated measures design, we found no difference in lifted mass or lumbar compression force at lift initiation between standing and seated lifts.

Jerry can carriage is an effective predictor of stretcher carry performance.

Carrying a casualty on a stretcher is a critical task conducted in a range of occupations. To ensure that personnel have the requisite physical capacity to conduct this task, two bilateral jerry can carries were used to predict individual performance in a four-person stretcher carry. Results demonstrated a bilateral 22-kg jerry can carry (R(2) = 0.59) had superior predictive ability of stretcher carry performance than a bilateral 15-kg jerry can carry (R(2) = 0.46). Pre- to post-carry changes in grip endurance (p > 0.05), back-leg isometric strength (p > 0.05) and leg power (p > 0.05) were not significantly different between carry tasks. There was no significant difference in heart rate (p > 0.05) and oxygen consumption (p > 0.05) between the stretcher carry and either jerry can carry. Thus, on the basis of performance correlations and physiological measures, the 22-kg jerry can carry is an appropriate predictive assessment of four-person stretcher carriage. Practitioner Summary: This study investigated the ability of a jerry can carry to predict individual performance on a four-person stretcher carry. Performance correlations were substantiated with physiological measures to demonstrate similar physical requirements between task and test. These results can be used to set physical employment standards to assess stretcher carriage.

On the relationship between discrete and repetitive lifting performance in military tasks.

Military manual handling requirements range from discrete lifts to continuous and repetitive lifting tasks. For the military to introduce a discrete lifting assessment, the assessment must be predictive of the various submaximum lifting tasks personnel are required to perform. This study investigated the relationship between discrete and repetitive military lifting to assess the validity of implementing a discrete lifting test. Twenty-one soldiers from the Australian Army completed a whole-body box-lifting assessment as a one repetition maximum (1RM) and a series of submaximal lifting repetitions (% 1RM). Performance was measured between the number of lifting repetitions that could be performed at different intensities between 58 and 95% 1RM. A strong curvilinear relationship existed across the entire submaximal lifting range (r = 0.72, p ≤ 0.05). The model developed demonstrated a low predictive error (standard error of the estimate = 7.2% 1RM) with no differences detected in the relationship when comparing individuals of high and low strength. Findings support the use of a discrete functional lifting assessment in providing coverage of a broad range of military lifting tasks. Parallels can be drawn between the trend reported in the current study and weight-training exercises reported in the literature.

The relationship between maximal lifting capacity and maximum acceptable lift in strength-based soldiering tasks.

Psychophysical assessments, such as the maximum acceptable lift, have been used to establish worker capability and set safe load limits for manual handling tasks in occupational settings. However, in military settings, in which task demand is set and capable workers must be selected, subjective measurements are inadequate, and maximal capacity testing must be used to assess lifting capability. The aim of this study was to establish and compare the relationship between maximal lifting capacity and a self-determined tolerable lifting limit, maximum acceptable lift, across a range of military-relevant lifting tasks. Seventy male soldiers (age 23.7 ± 6.1 years) from the Australian Army performed 7 strength-based lifting tasks to determine their maximum lifting capacity and maximum acceptable lift. Comparisons were performed to identify maximum acceptable lift relative to maximum lifting capacity for each individual task. Linear regression was used to identify the relationship across all tasks when the data were pooled. Strong correlations existed between all 7 lifting tasks (rrange = 0.87-0.96, p < 0.05). No differences were found in maximum acceptable lift relative to maximum lifting capacity across all tasks (p = 0.46). When data were pooled, maximum acceptable lift was equal to 84 ± 8% of the maximum lifting capacity. This study is the first to illustrate the strong and consistent relationship between maximum lifting capacity and maximum acceptable lift for multiple single lifting tasks. The relationship developed between these indices may be used to help assess self-selected manual handling capability through occupationally relevant maximal performance tests.