Development of U.S. Army Tactical Brassiere (ATB) Sizing System

Abstract

In support of the development of the U.S. Army Tactical Brassiere (ATB), a sports bra for physical training activities, a three-phase study was designed and executed. The first-phase study (Choi-Rokas et al., 2022) investigated the relationship between overall coverage, design features, anthropometric characteristics, and mobility of seven commercial-off-the-shelf (COTS) sports brassieres to document the pros and cons of each design feature. As the results, a single COTS brassiere was ranked as the best out of all assessed sports brassieres, based on breast coverage, reduction of breast movement, and overall participants’ preference. The current study is the second phase of the three-phase study focusing on the development of the sizing system for the ATB. Previous studies and related references (including but not limited to periodicals, video tutorials, manufacturer brassiere sizing charts, websites, and media, etc.) focusing on methodologies to predict brassiere size and/or to develop brassiere sizing systems were reviewed. Communalities between reviewed methods show: 1. Bust Circumference and Underbust Circumference are the two main body dimensions used for developing brassiere sizing systems. 2. The resultant band size is always an even number, in inches, for conventional brassiere sizing system in the U.S. 3. Cup size is determined based on the difference values (delta) between Bust Circumference and Underbust Circumference or between Bust Circumference and brassiere band size. Regardless of the methods to calculate the delta, the brassiere cup size increases by one size as the delta increases every 1-inch. Based on this knowledge, a new method to develop a sizing system was established. In this method, brassiere band sizes are converted from Underbust Circumference values with various adding factors depending on the torso size (i.e., gradually reducing the adding factor from 4-inch, then 0-inch for Underbust Circumference of 34-inch or greater), and brassiere cup sizes are based on the delta between Bust Circumference and Underbust Circumference. Next, the most recent U.S. Army female Soldier anthropometric databases (ANSUR II), which includes both manual and three-dimensional (3D) body shape scans, were reviewed to confirm the availability of two main dimensions, Bust and Underbust Circumferences. Because Underbust Circumference is not available in the original database (ANSUR II), was extracted from the 3D scan. Since dimensions extracted from 3D scans are not identical to their measured counterpart (i.e., Measured Waist Circumference of person A vs. the scan extracted Waist Circumference from person A’s 3D scan), the current study performed additional analyses to minimize those differences. Using the data from ATB phase 1 study, the manual and scan extracted Underbust Circumference measurements were compared, and a simple linear regression analysis was performed to model and predict the manual Underbust Circumference measurements from 3D scan extracted measurements. Then, this model was applied to the Underbust Circumference extracted from ANSUR II 3D database, allowing for the predication of manual Underbust Circumference for each participant. Finally, the established sizing method was applied to U.S. Army databases to develop a brassiere sizing system with 10 different cup sizes and 7 different band sizes. Three band sizes, 32”, 34” and 36” accommodated 92.03% of the target U.S. Army population. A total of seven sister sizes (sizes that share the same cup volumes, i.e., 32D, 34C, 36B, 38A, etc.) were grouped to accommodate over 93% of the target population. Visualization on the results, as well as the topic of fit models are further presented and discussed in this paper.