Cyclists Need to Crosstrain

So tells the LA Times

Many factors contribute to osteopenia or osteoporosis (very low bone mineral density) in cyclists, but one of the culprits is the nature of the exercise itself. Cycling is a low-impact sport that puts little mechanical load on the bones. That's great if you have joint problems, but it's the weight-bearing nature of exercise that signals bones to create more mass. Without such stress, bones don't get stronger, making them more prone to injury.

A recent study in the journal Medicine & Science in Sports & Exercise found that competitive male road cyclists had significantly lower bone mineral density in their spines than a control group of men who were moderately physically active while doing other recreational activities. They were also more likely to have osteopenia and osteoporosis than those in the control group, despite the fact that the cyclists had a greater calcium intake.