Combined Effects of Sports Bra Support and Running Shoe Cushioning Influence Breast and Running Biomechanics in Female Runners

Abstract

Background: Sports bras play a critical role in running, with implications for breast discomfort, pain, performance, potential injury risk, and exercise participation for many women. While breast movement has been analyzed across support levels, most studies focus on discrete time-domain variables, such as peak impact acceleration. However, impact frequency content and tissue vibrations are also key factors that the body, and apparel components such as running shoes, may attenuate to maintain comfort and performance during running. This study explored how different sports bras and running shoes affect breast and foot-strike impact forces and comfort in female runners. Methods: Twenty-seven recreational female runners ran in four conditions that combined high and low support bras with high and low cushion shoes. Impact accelerations at the tibia and breast, breast-body time lag, and power spectral density in low, medium and high frequency ranges at the tibia and breast were measured. Participants also rated sports bra and shoe comfort. Results: Sports bra support significantly influenced peak breast acceleration, breast-body time lag, breast power spectral density across all frequency ranges, and perceived bra comfort and support ( p < 0.001 for all). Shoe cushioning significantly affected peak tibia acceleration ( p = 0.002) and shoe comfort ( p < 0.001). A significant interaction between bra and shoe conditions was observed for tibia power spectral density in the low- ( p = 0.03) and medium- ( p = 0.05) frequency ranges. Discussion: These findings demonstrate the interactive effect of sports bra support and shoe cushioning, and how sufficient upper body support may enable female runners to tolerate greater impact variability at the foot-strike level. Both sports bras and running shoes play important roles in managing impact and comfort during running, highlighting the need for female-specific design considerations in athletic gear.