Sports brassieres play an important role in the development of sports activities and the achievement of good records in female athletes. However, they have been designed not so scientifically since breast vibration in the brassiere cup is so complicated and the spatial relationship between the breasts and the brassiere has not been clarified. As a basic research for designing sports brassieres, breast vibration, changes in the clothing pressure and dislocation of breasts from the brassiere in running condition were analyzed using a method where the brassiere cup was removed for visualizing breast movements without deteriorating supporting function of the brassiere.
　Under the condition covered with the brassiere cup, breasts vibrated in running condition. Changes in the clothing pressure were most evident at the lower part of the cup. Clothing pressure at the lower part of the cup decreased with upward movements of the breast, while it increased with downward movements of the breast. Dislocation of the breast from the inside surface of the brassiere was noted resulting in the deterioration of fitting. The dislocation was most remarkable on the medial side of the lower cup especially in subjects with soft breasts. The breast vibrated at the same frequency of running, which caused changes in the clothing pressure and the dislocation of breasts from the brassiere.

DESCENTE SPORTS SCIENCE Vol.27/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE