Spinal alignment is like turnout, says Michael Kelly Bruce, associate professor of dance at The Ohio State University. "It's a mechanism, not an aesthetic." But as with turnout, dancers' visual goals often lead them to force their bodies into unnatural positions. "A healthier spine has to do with acknowledging the structural integrity of what's there, as opposed to changing it to meet that aesthetic," he explains. He compares a spine without its natural curves to winging the foot. "It's gorgeous in arabesque, but you don't want to stand on it. It's not very supportive," he says. Ballet dancers are particularly prone to extremes in erasing the curves from their backs. "People from New York City Ballet dance gorgeously, but in my opinion, their spines are weird," says Bruce.