First, according to the season to buy summer: sweat more, should wear pure cotton, bleached cloth or poplin fabric bra. Spring and autumn: Wear a polyester bra. Winter: Wear a chunky or sponge-lined bra. If the breasts do not grow, or the size of the left and right breasts is obviously asymmetrical, you can choose a protrusive-shaped bra lined with sponge. Second, the purchase of underwear for exercise and fitness should wear a sports bra when doing fitness and sports; Choose a good moisture absorption, breathability, comfortable wearing cotton or cotton and silk, cotton and high elastic spandex blended materials made of bra, chest strap should be wide, shoulder strap is best not easy to slide to both sides of the Y shape; The inner layer of the bra should be seamless design, so as to avoid strong skin friction during exercise. Third, choose the color of underwear with each person's favorite choice. But some dyes are carcinogenic. Dye can be absorbed by the human skin through sweat, dark underwear dye, if the fastness of the dye is not good, the skin will absorb more, the greater the harm. Dermatologists also believe that some skin diseases are likely to be caused by impurities such as dye shedding or intermediates. Therefore, it is best to choose underwear that is natural or light. Avoid dark red, Burgundy, navy, coffee, dark green and black. If you have a special preference for these colors, be sure to wash and change frequently, and don't be lazy. White underwear is not very safe, this product is often added a fluorescent white agent. According to recent studies, some fluorescent whitening agents are also carcinogens and can pollute water sources with washing emissions.