Evaluation of Shock Absorbing Performance of Sports Bras

Background Sports bras are generally used to support women's breasts by absorbing the shock energy induced by body motion. However, their shock absorbing performances in controlling breast displacement remain unclear. A better understanding on the reduction of breast displacements at different breast positions during activities will be necessary for the future development of optimal sports bras in order to prevent breast injury. Objective This study aimed to evaluate the shock absorption performance of different sports bras of different claimed support levels, and to analyze the factors involved. Methods 3 healthy females were invited to participate in the experiment. They wore 4 types of sports bras of 2 different support levels and performed 3 different activities (walking, running and stepping). Using a 6-camera Vicon motion capturing system, the movement of their left breast regions in different bras and activities were recorded. The changes of the 3D coordinates of 6 different breast positions were obtained. The breast displacement and the reduced percentage of controlled breast displacement (RBD) are proposed as two main parameters for evaluating the shock absorbing performance of sports bras. Results The naked breast displacement was ranged from 1.01 to 4.37 cm. The breast displacement was the largest during stepping, and at the bust point. However, the RBD was larger at outer breast when wearing sports bras. The magnitude of shock absorption did not agree with the support levels claimed by the manufacturers. The encapsulation bras were more effective than compression bras in controlling breast displacement. The design features such as the fiber contents, shoulder strap and neckline could also significantly influence the shock absorption of the bra. Conclusion A new index "RBD" (Reduced % of breast displacement) was used to evaluate the effectiveness of bra in shock absorption. The largest displacement occurred at the bust point. The RBD was the highest at the outer breast. The encapsulation bra EP-2 was the most effective shock absorber due to its higher content of polyamide, wider shoulder strap and higher neckline. However, the magnitude of shock absorption did not agree with the support levels claimed by the manufacturers.