Female Breast Motion During Exercise In Different Breast Support Conditions

Objective: In recent papers,displacement,speed and acceleration are mainly used in breast health researches.To study the effect of bra with different support intensity on the kinematics characteristics,stability,relationship with the trunk and vibration characteristics of women during running.The significance lies in summarizing the analysis method of breast movement,and provides the theoretical basis for the support strength classification of sports bra.Methods: 10 female students with B cup were selected.Three types of bra with daily bra,low support sport bra and high support sport bra.Each participant run on the treadmill with 10 km.h-1 speed on a treadmill(HP.Germany).Markers’ movement in space was captured by Motion System(USA),which included eight 200 Hz cameras.Establish nipple movement relative to the upper body and obtain the breast movement distance,displacement,deflection.Frequency was obtained by Fast Fourier Transform(FFT).The coefficient and delay of cross correlation show the relationship between breast and upper body.Results: With high support bra,horizontal displacement of breast was significantly less than the daily bra,sagittal and horizontal displacement were significantly less than the low support bra.High support bra breast downward offset greater than the nake,less than daily bra and low support bra,without significant difference.The main frequency of vertical displacement is 2.8Hz,the main frequency of the horizon is 1.45 Hz and the main frequency of sagittal movement is 1.4Hz.The amplitude of high support bra at the main frequency is smaller than other type of bras.4.The maximum Lyapunov exponent of breast in vertical direction was significantly lower than nake,and the time delay of cross-correlation function was significantly less than nake.Conclusion: 1.High level sports bra have a strong restriction on the breasts,which reduces the movement distance,left and right,and fore and aft direction displacements of the breasts during running.Low level bras and daily bras had no effect on the movement characteristics of women during running.2.High support level bras increase the stability of women’s running breasts,and the largest Lyapunov index can be used as a criterion for the definition of high support level bras.3.The cross-correlation delay between the vertical movement of the trunk and the breast is the reason for the large vertical displacement of the breast.4.High support level bras reduce the vertical vibration amplitude of the breast at 2x and 3x trunk frequency during running.