Developing a scientific understanding of the breast support implications for the female recreational athlete will make a significant contribution to the breast biomechanics literature, provide valuable information to bra designers and help athletes make informed decisions about their breast support requirements. The work in this thesis determined the effect of a high and low breast support condition on biomechanical and perceptual variables during steady-state running, intermittent exercise and vertical jumping in a population of larger-breasted female recreational athletes. In order to assess breast kinematics an appropriate method of assessing bra fit was needed. Within this programme of research the use of best-fit criteria was first developed and then demonstrated that traditional bra fit methods overestimate band size (76% of participants) and underestimate cup size (84% of participants). During all activity modes a well-fitted high support bra significantly (p < 0.05) reduced breast kinematics and increased breast comfort. For steady-state running, alterations in lower-extremity biomechanics led to more distance being covered per minute (3.08 m; p = 0.006) and therefore a potential for improved performance when participants ran with high breast support. More acute knee flexion during sprinting (p = 0.008) and less sagittal plane thorax range of motion (p < 0.044) in the high breast support condition during the intermittent treadmill protocol could also benefit running performance. Increases in the range of motion of upper-extremity variables during treadmill activity were related to increases in some breast kinematic variables (r = 0.465 to 0.742); therefore certain individuals may require greater breast support than others. With increased breast kinematics there was a trend towards participants landing from vertical jumps with lower ground reaction forces coupled with increased thorax, thigh and knee flexion (r = 0.564 to 0.607). This suggests participants attempted to soften their landing, which may affect subsequent performance. Vertical jumping and sprinting elicited the highest magnitudes of vertical (0.08 m) and mediolateral (0.03 m) breast displacement respectively, questioning whether steady-state running is the most effective activity mode for testing bra efficacy. The reduction of anterioposterior breast kinematics should also be a consideration for bra design as they related most closely to breast comfort and biomechanical variables across all activity modes. Knowledge of the breast support implications for larger-breasted female recreational athletes was progressed in this thesis and bras offering high multi-planar support are promoted as they were found to be beneficial for performance within the activities investigated.