First rule of fighting sag: The stakes get higher when you exercise. With each running stride, breasts move not only up and down but also side to side and in and out, tracing a butterfly pattern. Unsupported, the average A cup travels about an inch and a half in each direction, and a D cup bounces two to three inches.
A good sports bra can cut that movement in half — by 53 to 59 percent for As and Ds, respectively — which is key to sparing the support structures in your breast, says Joanna Scurr, PhD, a biomechanist at the University of Portsmouth in the United Kingdom who studies bounce. Because breasts are made of soft tissue — alas, not muscle — what holds them up is the surrounding skin and the internal Cooper’s ligaments, a web of springy coils that are built to rebound until jumping, genetics, and gravity catch up with them. “Any permanent stretching of these can cause the breasts to droop,” Scurr says.
Your breast defense? A good offense. Maximize your lift with these expert sports bra tips.
What to Do Before You Buy a Sports Bra
How do you know that the sports bra you pulled off the rack will hold up your, er, rack? “Support comes from three points on a sports bra: the straps, the cups, and the band, including the side panels,” says Susan Sokolowski, senior innovation manager for Nike in Beaverton, Oregon. Here’s how to dressing-room test all three.
Straps: Hold the top of one strap and the center of the corresponding cup, then pull. Whether they’re adjustable or not, the less stretchy the front straps, the more motion control they’ll provide.
Cups: Repeat a similar stretch test by tugging the top and bottom of each cup; the less give, the more motion control. Then put on the bra. Whether it’s a compression or an encapsulation style, the cup should hold the whole breast — no spillage. If it doesn’t, choose the next larger cup size.
Band and side panels: Slide a finger under the band between your breasts; you should not be able to pull it more than an inch from your chest. (For an adjustable band style, set the clasp on the first eyelet; if you have to use the last eyelet to get a snug fit, you’re better off with a smaller band.) Next, reach your arms overhead; if the band creeps up, it’s too big. In both cases, pick a smaller size.