Clothing and Equipment Fit Among Male and Female Canadian Armed Forces Members.

INTRODUCTION: The fit of military clothing and equipment is essential for the health and safety of military operators. Given the aim of increasing the proportion of women and the known biological and morphological differences between male and female soldiers, an understanding of fit across different items of kit is needed. The aim of this study was to quantify subjective fit ratings of 8 items of military clothing and equipment, including combat shirt, combat pants, rucksack, small pack, tactical vest, fragmentation vest, helmet, and ballistic eyewear as a function of relative stature and occupational group among male and female Canadian Armed Forces members. MATERIALS AND METHODS: An online survey was distributed to male and female Canadian Armed Forces members, where fit was reported by participants according to a 7-point Likert acceptability scale. Participants were binned into 1 of 6 (3 males, 3 females) standing stature categories based on percentiles in a male and female distribution that included (1) under 35th percentile stature, (2) 35th to 80th percentile stature, and (3) over 80th percentile stature. Additionally, participants were separated according to occupational group: Group A: Infantry, Combat Engineer, Artillery, Armored; group B: Signals, Medical Technician, Intelligence, Signals Intelligence/Cyber Ops; group C: Supply Technician, Weapons Technician, Vehicle Technician, Electronic-Optronic Technician, Ammunition Technician; other: Not in other groups, examples include: Financial Services Administrator, Cook. This study was approved by the Defence Research and Development Canada Human Research Ethics Committee under protocol 2019-048, Amendment 2. RESULTS: There were significant effects attributable to stature category and occupational group on the fit of equipment. Specifically, fit acceptability of the rucksack helmet, small pack, and tactical vest was significantly affected by occupational group. Differences between stature categories were detected in all items with the exception of the small pack. CONCLUSIONS: Military equipment fit has previously been shown to have implications for protection, performance, and mobility. The results of the investigation demonstrate different patterns of fit acceptability in male and female soldiers across items of clothing and equipment and may require different solutions.

Comparison of In-service Reduced vs. Full Torso Coverage Armor for Females.

INTRODUCTION: Body armor and torso-borne equipment are critical to the survivability and operational effectiveness of a soldier. Historically, in-service designs have been predominantly designed for males or unisex, which may be disadvantageous for females who are shaped differently and, on average, smaller in stature and mass than their male counterparts. This study assesses the biomechanical and performance impact of two Canadian in-service armors and fighting load conditions on females. MATERIALS AND METHODS: Four tasks (i.e., range of motion, treadmill march [×2], and a wall obstacle) were performed in a Baseline condition and two in-service torso-borne equipment conditions; the full torso coverage (FTC) condition has full upper torso soft armor with the fighting load carried in a separate vest, while the reduced coverage (RC) has a plate carrier with fighting load integrated into the armor carrier, bulk positioned higher, and less torso coverage. Both used identical combat loads and front and back armor plates. Trunk range of motion, march lower limb kinematics, march shoulder and hip skin pressures, perceived discomfort after the march, and time to traverse a wall obstacle were captured. Data were collected to assess the biomechanics and usability of the systems for eight females, representative of military recruits. Linear mixed-effects models were created, and analysis of variances (ANOVAs) were then performed on all the outcome measures (P < .05). Tukey's post-hoc procedures were performed when appropriate (P < .05). RESULTS: There were significant differences between the RC and FTC for the sit and reach test (P < .001), lateral bend test (P < .001), and wall traverse time (P < .01). In all cases, the RC outperformed FTC. There were no differences between the two in-service conditions with respect to hip, knee, and ankle flexion/extension. The RC average skin pressure was higher than the FTC at the left and right shoulders by 103% and 79%, respectively, and peak skin pressure at the left shoulder by 75%. Both in-service conditions showed decrements in performance from Baseline for sit and reach (P < .001), lateral bend (P < .001), and peak hip and knee flexion (P < .01) with the FTC showing decreases in trunk rotation (P < .001) and wall traverse time (P < .01). CONCLUSIONS: Improved outcomes for the RC can be attributed to design differences. The lower placement of bulk in FTC may act as a physical barrier during range of motion tasks and the wall obstacle. The presence of shoulder caps on FTC provides another physical barrier that likely impedes full movement through the arms and shoulders. While the narrower shoulder straps of the RC remove the barrier, it causes more concentrated skin pressures on the shoulder that can lead to injury. The results suggest that the RC offers a potential for increased operational effectiveness in females (and potentially for males) compared to the FTC system. Shoulder pressure, an important predictor of discomfort and injury, is the only measure for which FTC outperformed the RC. Future torso-borne equipment designs targeting this outcome measure could help increase the effectiveness of the RC and other similar systems that reduce torso coverage, though survivability implications must also be considered.

Biomechanical and physiological effects of female soldier load carriage: A scoping review.

Loads carried by military populations can affect those of smaller stature, such as the average female, due to the higher percentage of body weight the loads represent. Despite this, most load carriage research is performed on males. Peer reviewed articles were collected from four databases to summarize available research on biomechanical and physiological effects of load carriage on females in the military. Extraction and thematic analysis were performed on 18 articles. 39% looked at biomechanical differences between loads in females, 61% looked at how the same load affected males and females, 44% looked at sex-by-load interaction effects, and 72% discussed impacts of load on females. The research revealed that military load carriage affects the biomechanics and physiology differently in females and to a greater extent than in males. Several gaps in available literature were found. Very few studies used military participants, military equipment, and/or employed occupationally relevant data collection methodologies.

A data-driven framework for assessing soldier performance, health, and survivability.

Presented is a framework that uses pattern classification methods to incrementally morph whole-body movement patterns to investigate how personal (sex, military experience, and body mass) and load characteristics affect the survivability tradespace: performance, musculoskeletal health, and susceptibility to enemy action. Sixteen civilians and 12 soldiers performed eight military-based movement patterns under three body-borne loads: ∼5.5 kg, ∼22 kg, and ∼38 kg. Our framework reduces dimensionality using principal component analysis and uses linear discriminant analysis to classify groups and morph movement patterns. Our framework produces morphed whole-body movement patterns that emulate previously published changes to the survivability tradespace caused by body-borne loads. Additionally, we identified that personal characteristics can greatly impact the tradespace when carrying heavy body-borne loads. Using our framework, military leaders can make decisions based on objective information for armour procurement, employment of armour, and battlefield performance, which can positively impact operational readiness and increase overall mission success.

Determination of Orientation and Practice Requirements When Using an Obstacle Course for Mobility Performance Assessment.

OBJECTIVE: Determine effect of orientation (introduction and familiarization) and practice (repeated performance) on human performance under various load conditions as assessed by an obstacle course. BACKGROUND: Obstacle courses are commonly used as screening tools by military, police, and firefighters or to assess human capabilities and the effect of wearing personal protective equipment (PPE) and other occupationally necessary equipment on mobility task performance. Unfortunately, little is formally documented about the effect of orientation and practice on performance outcomes of obstacle or mobility courses being used. METHOD: Forty-eight participants were recruited from the Canadian Army Infantry and Combat Engineer population. Participants either received regular or extensive orientation of the course before completing it. Following orientation, participants completed the course five consecutive times while wearing their PPE with full fighting order (FFO) and five consecutive times while wearing no PPE and non-FFO across a five-day period (maximum two runs per day), with ensemble presentation order counterbalanced. Total course completion time and individual obstacle completion times were measured for each run of the course. RESULTS: While wearing FFO, participants continued to decrease the time required for completing the course; however, while wearing non-FFO, time to course completion did not significantly change over the five runs. There were no differences in course completion times for the regular and extensive course orientation groups. CONCLUSIONS: Considerations required to mitigate orientation and practicing effects can differ depending on type or complexity of load condition. While wearing FFO, practicing effects can introduce undesired confounding factors into data collection. APPLICATION: Any practice runs on an obstacle course prior to its use as an assessment tool should focus on the loaded (e.g., FFO) condition because improvement on loaded runs is likely transferred to unloaded, but this does not apply in the reverse.

Development and assessment of the Canadian personal load carriage system using objective biomechanical measures.

The Defence Research and Development Canada--Toronto managed a collaborative team of designers, biomechanists, ergonomists and military stakeholders in the development of a new personal load carriage (LC) system for the Canadian Forces. Ergonomics design principles using objective measurement tools and user-centred feedback from soldiers were considered essential to system development. The purpose of this study was to provide a detailed report of contributions by biomechanical testing to the final design of the final Canadian LC system. The Load Carriage Simulator and Compliance Tester were used to test design iterations of: three fragmentation vests, seven tactical vests and three iterations of the backpack. Test data were compared to a data pool of seventeen previously tested systems. Results indicated that the objective measures helped the design team by: (1) quantifying and understanding the consequences of various design changes; (2) predicting soldiers' responses to design changes in skin contact pressure, force and relative motion; (3) objectively comparing design iterations to other systems; and (4) providing information quickly so that ideas and recommendations could be incorporated into the next design iteration. It was concluded that objective assessments added valuable information not easily interpreted from human trials. However, objective assessments cannot replace human trials for feedback on functionality and features.