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.

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.

Indices of physiological strain for firefighters of the Australian Defence Forces.

High levels of exertion and physiological strain are the leading cause of fireground injuries. The Physiological Strain Index (PSI) provides a rating of strain based on body core temperature and heart rate; however, it may underestimate the strain of workers in protective clothing as skin temperature may be elevated. This study aimed to examine the relationship between the PSI and an Adaptive Physiological Strain Index (aPSI) that incorporates skin temperature, among firefighters wearing protective clothing. Nine male firefighters of the Australian Defence Force volunteered to participate. Participants conducted scenario-based activities while wearing turnout gear and breathing apparatus. Working in teams of four, participants would respond to a situation around and within a small building with several rooms that could be filled with smoke, however, no live fire was present. Heart rate, gastrointestinal temperature, and skin temperature were monitored throughout work and rehabilitation. Physiological strain was estimated via the PSI and aPSI. Absolute peak PSI and aPSI ratings were significantly different during work (PSI: 7.3 ± 1.6; aPSI 8.2 ± 2.0; p < 0.001). The aPSI produced higher ratings of physiological strain, >0.5 above PSI, progressively from a moderate level of strain (>6). The aPSI may provide a more accurate indication of a level of "maximal strain" for encapsulated workers than the original PSI, coincident with the occupational limits for body core temperature of 38.0 °C for general occupational groups, or 38.5 °C for selected and acclimatised personnel.

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.

Tactical combat movements: inter-individual variation in performance due to the effects of load carriage.

An examination into the effects of carried military equipment on the performance of two tactical combat movement simulations was conducted. Nineteen Airfield Defence Guards performed a break contact (five 30-m sprints) and a fire and movement simulation (16 6-m bounds) in five load conditions (10-30 kg). Heavier loads significantly increased movement duration on the break contact (0.8%/kg load) and fire and movement (1.1%/kg). Performance deterioration was observed from the beginning to the end of the series of movements (bounds or sprints) with deterioration becoming significantly greater in heavier load conditions. Inter-individual variation between slower and faster participants showed a range in load effects; 0.6, 0.8%/kg for fast and 1.0, 1.4%/kg for slow (break contact, fire and movement, respectively). Velocity profiles revealed that the initial acceleration and peak velocity were the primary determinants of performance. As the duration of these tactical combat movements reflects periods of heightened vulnerability, these findings highlight important implications for commanders. Practitioner Summary: Increasing amounts of carried military equipment impairs the performance of tactical combat movements. Examination of inter-individual variation in velocity profiles identified that the initial acceleration and the peak velocity achieved during sprints and bounds are key determinants of overall performance.

Effects of Military Load Carriage on Susceptibility to Enemy Fire During Tactical Combat Movements.

Current military operations require soldiers to carry heavy external loads that are widely acknowledged to impair the ability to move tactically on the battlefield. However, to date, the effect of load on susceptibility to enemy fire (the probability of being hit) has not been examined. Nineteen soldiers completed a break contact simulation (five 30-m sprints commencing every 44 seconds) and a fire and movement simulation (sixteen 6-m bounds commencing every 20 seconds) in each of the 5 load conditions (ranging from 9.8 to 30.1 kg). For each simulation, the impact of load on exposure time and peak movement velocity was examined. In addition, the 6 fastest and 6 slowest soldiers (determined by exposure time in the heaviest condition) were parsed into subgroups to examine interindividual differences in response to load. Susceptibility for the 2 subgroups was modeled using exposure time for the 2 simulations and the assumed reaction time, shooting cadence, and shooting accuracy of the enemy. Susceptibility increased as a function of load for both the break contact and fire and movement simulations and became more pronounced when the participant population was parsed into fast and slow groups. When the impact of personal protection systems was isolated and analyzed, it was found that not only were the slower participants more vulnerable (as a result of not wearing the personal protection system) but also more susceptible than the faster participants who carried 11.2 kg more load. Large interindividual differences in response to external load have meaningful consequences for battlefield susceptibility, and it is therefore critical that personnel are afforded tailored training such that they maximize their proficiency in the execution of tactical combat movements.

How Effective Is Initial Military-Specific Training in the Development of Physical Performance of Soldiers?

The impact of basic military training (BMT) on recruit physical performance is well described. However, initial employment training (IET), the period immediately after BMT, is the final preparatory step before posting to an operational unit. There is limited evidence on the influence of this training in developing the physical attributes necessary for military duty. Therefore, this investigation determined the relative contribution of BMT and IET to develop physical capability in soldiers. Fifty-one soldiers (45 men and 6 women) were assessed at 4 time points: commencement of training (week 1), midway (week 8), at the conclusion (week 12) of BMT, and upon completion of the IET (week 18/27). Weeks 1, 12, and 18/27 are reported herein. At each time point, tasks relevant to military duties, such as 1 repetition maximum (1RM) box lift, 2 × 22 kg-jerry carry, 3.2 km of 22-kg load carriage, and preexisting assessments of military fitness, such as 20-m shuttle run, 2-minute push-ups, and sit-ups, were assessed. A subsample of recruits (n = 14) was assessed for 1RM bench press, vertical jump, 30-second high-intensity cycle ergometry, and peak treadmill oxygen consumption. A significant (p ≤ 0.05) decrease in 3.2 km of 22-kg load carriage (week 12, 1,109 ± 37 seconds; week 18/27, 1,161 ± 51 seconds), 2 × 22 kg-jerry carry (week 12, 753 ± 72 m; week 18/27, 683 ± 78 m), and 1RM bench press (week 12, 83.3 ± 16.0 kg; week 18/27, 73.2 ± 16.6 kg) was observed during IET. No change (p > 0.05) between week 12 and week 18/27 was detected in 1RM box lift, vertical jump, 30-second high-intensity cycle ergometry, sit-ups, and 20-minute shuttle run. In contrast, 2-minute push-up (week 12, 46.7 ± 2.7; week 18/27, 57.5 ± 3.1) performance increased significantly (p ≤ 0.05). Soldiers who participated in up to 15 weeks of additional IET did not make further physical performance gains in strength, power, and endurance or function before posting to their units. Thus, greater focus on the development of these physical attributes seems warranted within the IET training regimen.

The Effectiveness of Basic Military Training To Improve Functional Lifting Strength in New Recruits.

Australian Army recruits are required to meet the incumbent baseline physical employment standards (PES) during basic military training. A box lift and place (BLP) assessment is included in the PES, and it assesses the ability to perform essential muscular strength tasks. Therefore, basic military training must provide sufficient training stimulus to enable recruits to achieve the baseline BLP standard. A study was undertaken to investigate changes in the performance of 1-repetition maximum BLP in male (n = 154; age, 21.4 years) and female (n = 20; age, 23.1 years) recruits over the first 8 weeks of a 12-week basic military training course. Both male and female recruits showed modest improvements (2.2 ± 5.9 kg and 3.0 ± 3.1 kg, respectively; p ≤ 0.05) in maximal BLP performance, and there were no differences between genders. The female recruits showed greater relative improvements compared with the male recruits (14.7 ± 7.8% vs. 6.5 ± 2.3%). Despite the modest improvements in BLP performance, 70% of female and 100% of male recruits achieved the baseline BLP standard (25 kg) during week 8. The 30% failure rate for female recruits, however, suggests that the basic training program should be improved. A training program that yields greater gains in muscular strength would likely increase female recruit BLP pass rates. Augmented muscular strength would also likely increase the number of recruits capable of achieving higher BLP standards for more physically demanding employment categories. A training program that yields greater improvements in muscular strength may also enable lower entry standards, thereby increasing the recruit pool.

Development and Implementation of Evidence-Based Physical Employment Standards: Key Challenges in the Military Context.

The use of evidence-based physical employment standards is critical in selecting individuals who can meet the requirements of arduous military occupations. The methods used to generate the physical assessments and standards are critical to the process and must withstand legal scrutiny. This article addresses the challenges encountered when developing, validating, and implementing physical standards and assessments. The challenges covered by the study include: (a) identification of critical job tasks and minimum requirements for performance of the tasks, (b) involvement of military personnel as subject-matter experts,

Maximal and sub-maximal functional lifting performance at different platform heights.

Introducing valid physical employment tests requires identifying and developing a small number of practical tests that provide broad coverage of physical performance across the full range of job tasks. This study investigated discrete lifting performance across various platform heights reflective of common military lifting tasks. Sixteen Australian Army personnel performed a discrete lifting assessment to maximal lifting capacity (MLC) and maximal acceptable weight of lift (MAWL) at four platform heights between 1.30 and 1.70 m. There were strong correlations between platform height and normalised lifting performance for MLC (R(2) = 0.76 ± 0.18, p < 0.05) and MAWL (R(2) = 0.73 ± 0.21, p < 0.05). The developed relationship allowed prediction of lifting capacity at one platform height based on lifting capacity at any of the three other heights, with a standard error of < 4.5 kg and < 2.0 kg for MLC and MAWL, respectively.

Effect of load carriage on performance of an explosive, anaerobic military task.

This study examined the effects of load carriage on performance of an explosive, anaerobic military task. A task-specific assessment requiring five 30-m timed sprints was developed to address this question. Seventeen soldiers (female = 5, male = 12) volunteered to undergo the test under two experimental conditions: unloaded (combat uniform and boots) and loaded (unloaded plus 21.6 kg fighting load, comprising webbing, weapon, helmet, and combat body armor). When loaded, there was a significant increase in the mean 30-m sprint time compared to unloaded (8.2 +/- 1.4 seconds vs. 6.2 +/- 0.8 seconds; p < 0.01). Of the total increase in mean sprint time, 51.7% occurred within the first 5 m. Female sprint times were affected to a larger extent than male (36% vs. 29%, respectively) as a result of the increased load. Fighting load significantly affected soldier mobility when conducting explosive, anaerobic military tasks, particularly among females, and specific physical conditioning should be considered to minimize this effect.

The implications of emerging technology on military human performance research priorities.

OBJECTIVES: To demonstrate the need for the military human performance research community to anticipate and evolve with the emergence of new and disruptive battlefield technologies that are changing the fundamental role of the human combatant. METHODS: An international team of military performance researchers drew on relevant literature and their individual national perspectives and experiences to provide an integrated forecast of research priorities and needs based on current trends. RESULTS: Rapid advances and convergence in fields such as robotics, information technology and artificial intelligence will continue to have a revolutionary impact on the battlefield of the future. The disruption associated with these technologies will most acutely be experienced by the human combatant at the tactical level, with increasing cognitive demands associated with the employment and use of new capabilities. New research priorities may include augmented performance of humans-machine teams, enhanced cognitive and immunological resilience based on exercise neurobiology findings, and psychophysiological stress tolerance developed in realistic but safe synthetic training environments. Solving these challenges will require interdisciplinary research teams that have the capacity to work across the physical, digital and biological boundaries whilst collaborating seamlessly with end-users, human combatants. New research methodologies taking full advantage of sensing technologies will be needed to provide rigorous, evidence-based data in real and near-real world environments. Longer term research goals involving biological manipulation will be shaped by moral, legal and ethical considerations and evolving concepts of what it means to be human. CONCLUSION: This paper outlines key recommendations to assist military human performance researchers to adapt their practice in order to match the increasing pace of military modernisation. By anticipating technological change and forecasting possible emerging technologies the military human performance research community can manoeuvre to prioritise research activities today in line with future needs and requirements.

International consensus on military research priorities and gaps - Survey results from the 4th International Congress on Soldiers' Physical Performance.

OBJECTIVES: The objectives of this study were to identify perceived priorities related to military personnel's health and physical performance, among attendees at the 4th International Congress on Soldiers' Physical Performance (ICSPP), and to determine if perceived priorities had changed between the 3rd ICSPP survey held in 2014 and the 4th ICSPP survey held in 2017. DESIGN: Electronic survey. METHODS: Respondents were asked to grade priority areas on a Likert scale, and average ratings were used to rank priority areas. Responses to free text questions were analyzed qualitatively. Responses to the 4th ICSPP survey were described and compared to responses to the 3rd ICSPP survey. RESULTS: The 4th ICSPP survey respondents were a diverse group (40.6% military, 58.9% civilian). The two most important priority areas identified were physical demands in operational environments (mean score=4.41/5) and measuring physical performance/fitness (4.38/5), which were also the top two areas in the 3rd ICSPP survey. There was remarkable overlap in the rankings of priority areas between the two surveys. Sleep and nutrition were emerging priority areas and were perceived as relatively more important in the 4th ICSPP survey compared to the 3rd ICSPP survey. The greatest perceived emerging threat was resilience/psychological fitness of recruits (4.16/5). Physiological status monitoring (2.79/4) was identified as the most important technology. CONCLUSIONS: Despite the diverse backgrounds of the respondents, there was a clear continuing consensus about perceived important priority areas influencing military personnel's health and physical performance. Soldier resiliency and assessment of physiological status were research topics identified as top priorities.

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.

Consensus paper on testing and evaluation of military exoskeletons for the dismounted combatant.

Enhancing the capabilities of the dismounted combatant has been an enduring goal of international military research communities. Emerging developments in exoskeleton technology offers the potential to augment the dismounted combatant's capabilities. However, the ability to determine the value proposition of an exoskeleton in a military context is difficult due to the variety of methods and metrics used to evaluate previous devices. The aim of this paper was to present a standard framework for the evaluation and assessment of exoskeletons for use in the military. A structured and systematic methodology was developed from the end-user perspective and progresses from controlled laboratory conditions (Stage A), to simulated movements specific to the dismounted combatant (Stage B), and real-world military specific tasks (Stage C). A standard set of objective and subjective metrics were described to ensure a holistic assessment on the human response to wearing the exoskeleton and the device's mechanical performance during each stage. A standardised methodology will ensure further advancement of exoskeleton technology and support improved international collaboration across research and industry groups. In doing so, this better enables international military groups to evaluate a system's potential, with the hope of accelerating the maturity and ultimately the fielding of devices to augment the dismounted close combatant and small team capability.

Perspectives on resilience for military readiness and preparedness: Report of an international military physiology roundtable.

Modern warfare operations often occur in volatile, uncertain, complex, and ambiguous (VUCA) environments accompanied by physical exertion, cognitive overload, sleep restriction and caloric deprivation. The increasingly fast-paced nature of these operations requires military personnel to demonstrate readiness and resiliency in the face of stressful environments to maintain optimal cognitive and physical performance necessary for success. Resiliency, the capacity to overcome the negative effects of setbacks and associated stress on performance, is a complex process involving not only an individual's physiology and psychology, but the influence of factors such as sex, environment, and training. The purpose of this moderated roundtable was to address five key domains of resiliency in a point/counterpoint format: physiological versus psychological resiliency, sex differences, contributions of aerobic and strength training, thermal tolerance, and the role of nature versus nurture. Each speaker was given three minutes to present and the moderator facilitated questions and discussion following the panel's presentation. The interconnectedness of the five domains highlights the need for an interdisciplinary approach to understand and build resilience to enhance military performance.

The Pandolf equation under-predicts the metabolic rate of contemporary military load carriage.

OBJECTIVES: This investigation assessed the accuracy of error of the Pandolf load carriage energy expenditure equation when simulating contemporary military conditions (load distribution, external load and walking speed). DESIGN: Within-participant design. METHODS: Sixteen male participants completed 10 trials comprised of five walking speeds (2.5, 3.5, 4.5, 5.5 and 6.5km·h-1) and two external loads (22.7 and 38.4kg). RESULTS: The Pandolf equation demonstrated poor predictive precision, with a mean bias of 124.9W and -48.7 to 298.5W 95% limits of agreement. Furthermore, the Pandolf equation systematically under-predicted metabolic rate (p<0.05) across the 10 speed-load combinations. Predicted metabolic rate error ranged from 12-33% across all conditions with the 'moderate' walking speeds (i.e. 4.5-5.5km·h-1) yielding less prediction error (12-17%) when compared to the slower and faster walking speeds (21-33%). CONCLUSIONS: Factors such as mechanical efficiency and load distribution contribute to the impaired predictive accuracy. The authors suggest the Pandolf equation should be applied to military load carriage with caution.

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.