Study On Comfort Of Sports Bra Of Different Thickness During Walking And Running

Recreational activity is attracting more and more females,but the pain and discomfort caused by breast vibration becomes a big obstacle to female's exercise.Nowadays,many big sports bra manufacturers have produced lots of sports bra with different support level according to different exercise intensity.Sports bras with thick cup pads usually provide high level support.These sport bras also help to uplift breast for better shape,how they function dynamically still remain unclear.The purpose of this study is to investigate the effect of cup pad thickness and walking or running speed on breast movement and bra pressure.The achievement hopes to become scientific basis for sports bra design and also provide consumers purchase instruction.Five female college students of breast size 75 B volunteered participate the experiments: each bared breast or wearing one of five bras(daily bra,no pad sports bra and the same sports bra with pad of three thickness)walked or run on a treadmill at speed of 5km/h,7.5km/h,10km/h respectively for 5 minutes,breast movement was recorded at five points including left nipple and four surrounding points by using an 8-camera VICON motion capturing system and the pressure at the five points was also measured by using air pack pressure sensors.Relative displacement of the breast was then calculated through transforming the Global Coordinate Transformation(GCS)to a Breast Coordinate Transformation(BCS)established at a virtual origin inside the left breast.The results are as follows:(1)During jogging and fast running in no bra,the vertical breast displacement amplitude was primary(up to 30.8mm when jogging),the anteroposterior displacement amplitude was less than vertical displacement(up to 16.7mm when jogging),and the mediolateral displacement amplitude was least(up to 14.0mm when jogging).at each speed,the maximum vertical displacement amplitude was usually at the point 5 cm right to nipple(up to 34.7mm when the running speed was 10km/h),the minimum vertical displacement amplitude was usually at the point 5 cm left to nipple(up to 24.1mm when the running speed was 10km/h).At vertical direction,the breast displacement amplitude increased with the running speed(when the speed was 5km/h,the displacement amplitude of the point 5 cm right to nipple was 17.2mm,when the speed increased to 7.5km/h and 10km/h,the displacement amplitude up to 30.7mm and 34.7mm).There was no significant change of anteroposterior displacement amplitude and mediolateral displacement amplitude with the speed increased.(2)Wearing bra can reduced breast displacement in all directions,the maximum reduction was in vertical(compared to no bra,the maximum reduction was 19.3mm).In the vertical,after wearing sports bra,the maximum displacement amplitude was usually at the point 5 cm right to nipple(up to 13.9mm when the running speed was 10km/h),the minimum displacement amplitude was usually at the point 5 cm left to nipple(up to 9.5mm when the running speed was 10km/h).After wearing each experimental bra,except bra-B3,the breast displacement amplitude increased significantly with increasing speed(the displacement amplitude of the point 5 cm right to nipple increased from 5.6 mm to 13.9 mm).Increasing cup pad thickness had no significant effect on the displacement amplitude of 5km/h,but it had significant effect on the displacement amplitude of 7.5km/h and 10km/h(the maximum reduction was 2.4mm).The increasing thickness of cup pad and running speed did not show significant combined effects on breast displacement.(3)When wearing each experimental bra,the maximum static pressure was usually at the point 5 cm below nipple(up to 1.35 k Pa when weared bra-B3),and the minimum pressure was usually at the point 5cm upper nipple(up to 0.69 k Pa when weared bra-B3).The static pressure increased with increasing pad thickness(the pressure on the point 5cm below nipple increased from 0.91 kpa to 1.35kpa).When jogging and fast running,breast dynamic pressure changed periodically.The maximum dynamic pressure was usually at the point 5 cm below nipple(up to 1.9k Pa).The pressure of the point 5 cm below nipple increased with the thickness of cup pad(the maximum increase range was 0.65kpa),The pressure of the point 5 cm upper nipple decreased with the thickness of cup pad(the maximum decrease range was 0.42kpa).The other points on breast were less affected by the cup pad thickness.