The biomechanical and perceptual impact of breast support during riding and running in female equestrians

Popular among women, equestrian sport is the only sex-integrated Olympic sport, relying on interspecies communication between horse and rider. Despite extensive breast research in sport, equestrian research is limited. This study investigated the impact of bras on breast movement, comfort, and pain; rider position and asymmetry; and compared breast movement and pain in riding versus running. Participants (n = 21) rode a Racewood™ Equine Simulator (ES) in walk, trot, and canter and ran on a treadmill (TM) in four breast support conditions: everyday (EB), encapsulation sports bra (ESB), combination sports bra (CSB), and bare-breasted (BB). Markers were tracked by a Qualisys motion capture system, and relative breast displacement (RBD) in TM and ES was calculated, along with rider position during ES. Exercise-induced breast pain (EIBP) and bra comfort were measured on 0–100 visual analogue scales, and a survey on bra performance and aesthetics was completed. TM caused the highest EIBP (mm) (x̃ = 67.25, P < 0.001) and RBD (cm) (x̃ = 5.56, P < 0.001) in BB. A moderate positive association (rs(19) = 0.428, P < 0.001) was observed between EIBP and RBD, both of which were reduced by ESB (EIBP P < 0.001; RBD P < 0.002) and CSB (EIBP P < 0.001; RBD P < 0.001) in trot and TM. In trot, torso position improved in ESB (Z = −3.841, P < 0.001) and CSB (Z = −3.806, P < 0.001) compared to EB, and riders were most symmetrical in ESB. Bra comfort and preferences were idiosyncratic. Bra type meaningfully influenced EIBP, rider position, and symmetry. Future larger, longitudinal, field-based studies are warranted.