The Effects Of Different Sports Bras Strap Structures On Kinematics And Muscle Activities

Objective: Comparing the effects of different sports bras straps on the control of breast movement and muscle activity during running.By combining the pressure and the questionnaire,proposing the choice of sports bras for female runners,and putting forward suggestions for the design of sports bra in the future.Methods: Fourteen women with B-C cups run bare breast and sports bras with three different straps on a treadmill at 9 km/h for 10 minutes.Using Motion high-speed infrared motion capture system(8 cameras)to collect the kinematic data(200Hz).Using DELSYS to collect electric signals(2000Hz).Using the NOVEL to collect the pressure of bras.Resuls: 1.H-type strap's pressure in the scapula was significantly smaller than that X-type and O-type strap.2.The displacement of H-type bra was significantly larger than that of the X-type and the O-type,and no significant with bare breast in the anteroposterior direction.The reduction of displacement percentage of the H-type bra was significantly smaller than that of the X-type and the O-type in the anteroposterior direction.The reduction of displacement percentage of the H-type bra was significantly smaller than that of the O-type in the mediolateral direction.The reduction of displacement percentage of the H-type bra was significantly smaller than that of the X-type and the O-type in the vertical direction.3.At 1.5km,Pectoralis major's RMS and IEMG of bare breast were significantly different from that of O-type.Anterior deltoid's RMS and IEMG of bare breast were significantly different from that of H-type.Lower trapezius' s RMS and IEMG of X-type were significantly different from those of the H-type.There was significant difference in the muscle activity of the bare breast and the same sports bra.Conclusion: 1.Three types sports bra,with the exception of strap,the size and pressure of the different straps is similar.The different back structures result in different back pressure,H-type strap's pressure in the scapula is smaller than X-type and O-type.2.The breast control effect of different strap structural design is different.The breast vibration amplitude when wearing the H-type sports bra is small in the vertical direction.While the breast vibration amplitude when wearing X-type and O-type sports bra is small in the anteroposterior and mediolateral direction.Indicating that the supporting role of breast when wearing the H-type structural design is better in the vertical direction,and the restriction of breast when wearing the X-and O-type structural design is better in the anteroposterior and mediolateral direction.3.There were significant differences in the activities of the muscles associated with bare-breasted and sports bras,which were significantly greater than those of wearing bra.There was little difference in muscle activity between the three sports bras.The exercise is longer,the more significant differences in muscle activity.