Purpose: This study aimed to quantify bra shoulder strap pressures, to investigate how bra strap cushions moderated this pressure and increased comfort, and to investigate the effects of variations in bra shoulder strap configuration on vertical breast motion, breast discomfort, shoulder pressures, and comfort.
Methods: Fourteen healthy women (C+ bra cup size) ran on a treadmill wearing a sports bra under five strap conditions (no straps, traditional vertical alignment, crossed-back alignment, and with and without bra strap cushions inserted under the straps). Bra shoulder strap pressure, vertical breast displacement, breast pain, and shoulder comfort were measured during each trial.
Results: Maximal pressures from 0.83 to 2.67 N·cm-2 and mean pressures from 0.52 to 1.06 N·cm-2 were recorded during running. The bra strap cushions only reduced maximal shoulder strap pressure in the crossed-back strap orientation. Vertical breast displacement was significantly less in the crossed-back orientation compared with no straps, and breast pain was significantly reduced in both the traditional and crossed-back orientation compared with the no strap condition. No significant between-condition difference was found in shoulder comfort regardless of shoulder strap orientation, although the crossed-back strap orientation resulted in significant increases in shoulder force and mean pressure values compared with the traditional strap orientation.
Conclusion: The bra shoulder strap cushion was not effective in decreasing the bra shoulder strap pressure due to design flaws that prevented it from adequately increasing the strap–shoulder contact area. However, modifying shoulder strap orientation from a traditional to a crossed-back configuration could alleviate the common problem of bra shoulder straps slipping off the shoulders of the wearer, without decreasing the overall efficacy of the sports bra in providing breast support.