Introduction The effect of breast support on running biomechanics (Milligan, 2013) and breast pain on upper-extremity kinematics during running (White et al., 2015) is investigated by different research groups. They mostly found a higher implication for females with large breasts and showed that the use of sports bras is generally beneficial compared to regular bras. A well-fitted supportive sports bra can increase an athlete's performance (Fong & Powell, 2022) and reduce the risk of injuries. The support properties of bras are conventionally evaluated by human trials. This is expensive and challenging when comparing the results of different studies. Methods Empa developed a manikin to investigate the load impact on the body (Wettenschwiler et al., 2017). This manikin was reshaped to a female upper body model equipped with breast prostheses for the realistic simulation of defined running conditions. A Polhemus motion tracking system was used to assess the relative movement of the manikin shell and the nipples during two simulated running conditions (8 km/h). A set of 16 sports bras was tested on the manikin regarding the reduction of relative movement of the nipples during running. In a first validation study, 6 of them were tested by human subjects during jogging (8 km/h) in 3 participants. The subjective support assessment was compared to the manikin data. Results A comparison of manikin measurement data (reduction in relative movement at 8 km/h) and subject data showed an excellent correlation (R2 > 0.95) for the subjective support assessment. The sports bra developed in this project reached high marks regarding support, thermal comfort, and fit. Discussion/Conclusion Preliminary data indicates that the female manikin is able to provide objective data about breast movement in line with the perceived support of sports bras. In combination with additional methods such as sensory and thermal comfort assessment, this new methodology provides a scientific basis for developing improved sports bras meeting specific requirements for various sports. References Fong, H. B., & Powell, D. W. (2022). Greater breast support is associated with reduced oxygen consumption and greater running economy during a rreadmill running task. Frontiers in Sports and Active Living, 4, Article 902276. https://doi.org/10.3389/fspor.2022.902276 Milligan, A. K. (2013). The effect of breast support on running biomechanics [Doctoral Dissertation, University of Portsmouth]. Wettenschwiler, P. D., Annaheim, S., Lorenzetti, S., Ferguson, S. J., Stämpfli, R., Psikuta, A., & Rossi, R. M. (2017). Validation of an instrumented dummy to assess mechanical aspects of discomfort during load carriage. PLOS ONE, 12(6), Article e0180069. https://doi.org/10.1371/journal.pone.0180069 White, J., Mills, C., Ball, N., & Scurr, J. (2015). The effect of breast support and breast pain on upper-extremity kinematics during running: Implications for females with large breasts. Journal of Sports Sciences, 33(19), 2043-2050. https://doi.org/10.1080/02640414.2015.1026378