Daniel C. Billing

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.

Heat strain during military training activities: The dilemma of balancing force protection and operational capability

ABSTRACT Military activities in hot environments pose 2 competing demands: the requirement to perform realistic training to develop operational capability with the necessity to protect armed forces personnel against heat-related illness. To ascertain whether work duration limits for protection against heat-related illness restrict military activities, this study examined the heat strain and risks of heat-related illness when conducting a military activity above the prescribed work duration limits. Thirty-seven soldiers conducted a march (10 km; ∼5.5 km h−1) carrying 41.8 ± 3.6 kg of equipment in 23.1 ± 1.8°C wet-bulb globe temperature. Body core temperature was recorded throughout and upon completion, or withdrawal, participants rated their severity of heat-related symptoms. Twenty-three soldiers completed the march in 107 ± 6.4 min (Completers); 9 were symptomatic for heat exhaustion, withdrawing after 71.6 ± 10.1 min (Symptomatic); and five were removed for body core temperature above 39.0°C (Hyperthermic) after 58.4 ± 4.5 min. Body core temperature was significantly higher in the Hyperthermic (39.03 ± 0.26°C), than Symptomatic (38.34 ± 0.44°C; P = 0.007) and Completers (37.94 ± 0.37°C; P<0.001) after 50 min. Heat-related symptom severity was significantly higher among Symptomatic (28.4 ± 11.8) compared to Completers (15.0 ± 9.8, P = 0.006) and Hyperthermic (13.0 ± 9.6, P = 0.029). The force protection provided by work duration limits may be preventing the majority of personnel from conducting activities in hot environments, thereby constraining a commanders mandate to develop an optimised military force. The dissociation between heat-related symptoms and body core temperature elevation suggests that the physiological mechanisms underpinning exhaustion during exertional heat stress should be re-examined to determine the most appropriate physiological criteria for prescribing work duration limits.

Predicting physiological capacity of human load carriage - a review.

This review article aims to evaluate a proposed maximum acceptable work duration model for load carriage tasks. It is contended that this concept has particular relevance to physically demanding occupations such as military and firefighting. Personnel in these occupations are often required to perform very physically demanding tasks, over varying time periods, often involving load carriage. Previous research has investigated concepts related to physiological workload limits in occupational settings (e.g. industrial). Evidence suggests however, that existing (unloaded) workload guidelines are not appropriate for load carriage tasks. The utility of this model warrants further work to enable prediction of load carriage durations across a range of functional workloads for physically demanding occupations. If the maximum duration for which personnel can physiologically sustain a load carriage task could be accurately predicted, commanders and supervisors could better plan for and manage tasks to ensure operational imperatives were met whilst minimising health risks for their workers.

Developing Physical Capability Standards That are Predictive of Success on Special Forces Selection Courses

This study aimed to develop minimum standards for physical capability assessments (vertical jump, sit and reach, push-ups, seven-stage sit-ups, heaves, agility, 20-m shuttle run, loaded 5-km pack march, and 400-m swim) that candidates must pass before they can commence Australian Army Special Forces (SF) selection courses. Soldiers (Part A: n = 104; Part B: n = 92) completed the physical capability assessments before commencing a SF selection course. At the beginning of these selection courses, participants attempted two barrier assessments (3.2-km battle run and 20-km march). Statistical analysis revealed several physical capability assessments were associated with performance on the barrier assessments and selection course outcome (Part A); however, these statistical models were unable to correctly classify all candidates as likely to pass or fail the selection course. Alternatively, manual analysis identified a combination of physical capability standards that correctly classified 14% to 18% of candidates likely to fail, without excluding any candidates able to pass (Part A). The standards were applied and refined through Part B and included completing the 5-km pack march in ≤45:45 minutes : seconds, achieving ≥level five on the sit-up test, or completing ≥66 push-ups. Implementation of these standards may reduce attrition rates and enhance the efficiency of the SF recruitment process.

The effectiveness of basic military training to improve functional lifting strength in new recruits

Abstract Drain, JR, Sampson, JA, Billing, DC, Burley, SD, Linnane, DM, and Groeller, H. The effectiveness of basic military training to improve functional lifting strength in new recruits. J Strength Cond Res 29(11S): S173–S177, 2015—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.

Balancing ballistic protection against physiological strain: evidence from laboratory and field trials

This project was based on the premise that decisions concerning the ballistic protection provided to defence personnel should derive from an evaluation of the balance between protection level and its impact on physiological function, mobility, and operational capability. Civilians and soldiers participated in laboratory- and field-based studies in which ensembles providing five levels of ballistic protection were evaluated, each with progressive increases in protection, mass (3.4-11.0 kg), and surface-area coverage (0.25-0.52 m(2)). Physiological trials were conducted on volunteers (N = 8) in a laboratory, under hot-dry conditions simulating an urban patrol: walking at 4 km·h(-1) (90 min) and 6 km·h(-1) (30 min or to fatigue). Field-based trials were used to evaluate tactical battlefield movements (mobility) of soldiers (N = 31) under tropical conditions, and across functional tests of power, speed, agility, endurance, and balance. Finally, trials were conducted at a jungle training centre, with soldiers (N = 32) patrolling under tropical conditions (averaging 5 h). In the laboratory, work tolerance was reduced as protection increased, with deep-body temperature climbing relentlessly. However, the protective ensembles could be grouped into two equally stressful categories, each providing a different level of ballistic protection. This outcome was supported during the mobility trials, with the greatest performance decrement evident during fire and movement simulations, as the ensemble mass was increased (-2.12%·kg(-1)). The jungle patrol trials similarly supported this outcome. Therefore, although ballistic protection does increase physiological strain, this research has provided a basis on which to determine how that strain can be balanced against the mission-specific level of required personal protection.

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

Abstract Billing, DC, Silk, AJ, Tofari, PJ, and Hunt, AP. Effects of military load carriage on susceptibility to enemy fire during tactical combat movements. J Strength Cond Res 29(11S): S134–S138, 2015—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.

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 (R2 = 0.76 ± 0.18, p < 0.05) and MAWL (R2 = 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. Practitioner Summary: Physical employment tests must be both practical and reflective of job task demands. This study illustrates the potential for the implementation of a single discrete lifting assessment to predict performance across numerous occupational lifting heights.

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

Abstract Reilly, TJ, Gebhardt, DL, Billing, DC, Greeves, JP, and Sharp, MA. Development and implementation of evidence-based physical employment standards: key challenges in the military context. J Strength Cond Res 29(11S): S28–S33, 2015—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, (c) development of tests and criterion measures linked to critical job tasks, (d) determination of test performance standards, (e) evaluation of bias for protected groups, and (f) implementation, development of test policies, and revision of tests and standards.

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

Abstract Groeller, H, Burley, S, Orchard, P, Sampson, JA, Billing, DC, and Linnane, D. How effective is initial military-specific training in the development of physical performance of soldiers? J Strength Cond Res 29(11S): S158–S162, 2015—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.