The US Marine Corps and the US Army have been engaged in efforts to evaluate improved body armor, including armor to protect the extremities. These efforts are focused on both body armor performance (i.e., ballistic protection) and armor effects on the physical performance of personnel (e.g., body flexibility, mobility, and agility).

The Integrated Dismounted Armor System™ (IDAS) was viewed most favorably of the three Extremity Armor Systems tested.
The purpose of this investigation was to provide an evaluation of the physiological, biomechanical, and physical performance effects of three extremity armor systems: the Integrated Dismounted Armor System™ (IDAS), Deltoid Protector/Lower Extremity Body Armor (DP/LEBA), and QuadGuard. Each of these systems weighed approximately 6 kg, and was designed to be worn with and to augment the torso protection provided by a tactical armor vest.

Extremity armor systems were tested with the Interceptor Multi-Threat Body Armor (IBA), which consists of the Outer Tactical Vest, collar, groin protector, and front and back Small Arms Protective Inserts. The IBA was also tested without any extremity armor as a baseline condition. The effects of these conditions on energy consumed during walking and running, and on walking and running movement patterns were analyzed. Additional phys ical performance meas ures involving militarily- relevant tasks requiring mobility and agility (repetitive box lift, grenade throws, 30-m rushes, and obstacle course runs) were recorded under the armor conditions tested, as were assessments of range of motion and the evaluation of human factors issues associated with armor wear. Three-dimensional body surface scans were also included for each condition tested in order to acquire data on the surface area covered by ballistic-protective material.

The findings from this study indicate that, compared with wearing only the IBA, use of extremity armor increases the energy consumed during walking and running, changes the biomechanics of gait, increases the ground reaction forces (GRFs) associated with locomotion, and negatively affects performance of some militarily-relevant physical tasks.

Differences obtained between the IBA alone and the IBA plus extremity armor on a number of objective measures taken in this study were attributable to the weight of the extremity armor. The impact of extremity armor weight was evidenced in longer times to complete physically demanding activities requiring speed of movement. The weight also resulted in increased energy usage and higher-magnitude GRFs during walking and running.

Weight was a predominant factor in distinguishing performance with the IBA alone from performance with the IBA plus extremity armor. The three types of extremity armor tested were highly similar to each other in weight, but there were design variations that yielded differences among the three systems on some of the performance measures. One aspect of design on which the systems differed was body surface area covered by ballistic-protective material. The Quad Guard, which had the greatest area coverage, encumbered movement of the lower extremities, and was selected by volunteers as the extremity armor they least preferred. Based on overall results of testing, performance with the QuadGuard differed from that with the IBA alone to a somewhat greater extent than performance with the other two extremity armor systems.

The IDAS had the least body area coverage, and it was selected by study volunteers as their most preferred extremity armor system. Overall results with the IDAS were somewhat better than those with the QuadGuard, and similar to those with the DP/LEBA.

Although differences among the extremity armor systems in body surface area covered by ballistic-protective material appeared to affect performance and user opinion, conclusions cannot be made from these results about the influence of area coverage on the performance measures employed here. The three types of extremity armor differed in design characteristics other than area coverage, and the effects of these characteristics cannot be isolated from effects of area coverage in the data acquired in this study.

The study volunteers definitely viewed the QuadGuard least favorably and the IDAS most favorably of the three extremity armor systems. The objective measures taken in this testing, however, did not reveal extensive differences among the systems. From the results on the objective measures, there is no basis to recommend that any of the three systems not be considered further for military use. The systems were not, however, tested for the thermal burden they impose on the user. The systems may well differ in this regard due to their different area coverage.

This work was done by Leif Hasselquist, Carolyn K. Bensel, Brian Corner, and Karen N. Gregorczyk of the U.S. Army Natick Soldier Research, Development, and Engineering Center. ARL-0143


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Evaluation of Three Extremity Armor Systems

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This article first appeared in the August, 2012 issue of Defense Tech Briefs Magazine.

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