Illumination | Spring 2008

But what happens along the way? What occurs between the time people are at their healthy peak of bone mass and the time they are at greater risk for a fracture?

In May 2006, Hinton began her search for answers by designing a cross-sectional study comparing athletes who run but don't bike with those who bike but don't run. Hinton planned to bring the two groups into the lab and take a scientific snapshot of their bone turnover, specifically looking at markers of bone formation and breakdown, along with levels of the hormones affecting that process. The result would provide an accurate measure of how running or cycling differentially affected bones.

Along with her former doctoral student, Randy Scott Rector, and two nutritional science undergraduates, Robert Rogers and Meghan Ruebel, Hinton next set about finding participants. The researchers posted flyers on the MU campus and at various Columbia bicycle and sporting goods stores. They also advertised the study on the Web sites of local cycling and running clubs.

Hinton's connection to the cycling community helped, too. As an undergraduate at the University of Wisconsin-Madison, Hinton was a scholarship member of the cross-country and track teams, an All-American her senior year. When a car accident ended her distance running career, she took up cycling. She now competes in 60- to 80-mile road racing events.

Hours of pedaling gives a person time to think, a circumstance that eventually led Hinton to a key insight. "Being involved in cycling increased my awareness of this group of people who spend a lot of time essentially weightless," she says. This "weightlessness" of cycling, she notes, is the crucial distinguishing characteristic between the cyclists and runners, one with potentially profound consequences for the skeleton.

Hinton's study included only men, young and middle-aged athletic males, a group not generally believed to be at risk for bone loss. In a recent e-mail, Hinton's colleague Stephen Sayers, an assistant professor of physical therapy at MU and expert on physical performance and aging, put it this way: "Osteoporosis is often thought of as an 'elderly woman's disease.' ... Male athletes probably never considered that they would be at risk for this condition because they probably view their training as a panacea to all debilitating conditions."

As she sits balanced on an exercise ball in her McKee Gym office, Hinton explains the logic behind her curious study cohort: Of the 44 million Americans with osteoporosis, only about two million are men. Scientists believe this disparity occurs, at least in part, because women, whose bones are less dense to begin with, experience an abrupt loss of estrogen during menopause that speeds up bone turnover. Men's levels of testosterone, on the other hand, drop more gradually. But bone loss happens, and men need to be aware of it.

Published by the Office of Research.