These bras do so much more extra things to protect your boobs than ‘everyday’ bras. It’s been well publicised that a good sports bra can reduce the bounce of your boobs by 50%. Sports bras are generally tighter, very structured and help reduce movement of the breasts. Many of them have fabrics designed to take the moisture away from the skin which helps us to stay cooler and dry. They also are made with mesh fabrics for circulation and the cups are lined to stop the nipples from chaffing.