Dr. Jeanne Nichols, PhD, a professor of ex.rcise andnutrition and a serious cyclist, was conducting bond density studies of veteran bike racers and endurance riders. Ultimately, she examined the bones of 27 Masters racers and endurance riders, like Penseyres and Templin, who had an average of age of 51.2 and trained an average 12.2 hourrs a week for 20 years. Her study, "Low Bone Mineral Density in Highly Trained Male Masters Cyclists," was published in the August 2003 issue of Osteoporosis International. And her conclusions, communicated in an article by this coauthor published in the March 2004 issue of Bicycling Magazine, would stun the bike world: Anyone who rides a bike as his or her main form of fitness is risking osteoporosis...

...In Nichols's study of 27 male riders, however, two-thirds showed at least "osteopenia," moderate bone loss. Four of those had severe bone thinning, or osteoporosis. The test group's average hip and spine bone densities were 10 percent lower than a control group of similar aged, moderately athletic noncycling men.

When I remarked to Nichols that 10 percent didn't seem like a big deal, she was agast.

"Clinically, 10 percent thinning is significant--not good--almost frightening," she said. "Because at age 50, average men have no bone loss at all..."