Could competitive cyclists be putting their bone health at risk?

A disquieting new study of bone density in elite cyclists and runners suggests that the answer might be yes. The study found that the cyclists, both male and female, had thinner bones than the runners, even though all of the athletes were young, healthy and enviably fit, and many of the cyclists lifted weights.

The results underscore the divergent effects of various sports on our skeletons and also stir a little unease about the long-term impacts of pursuing low-impact exercise at the expense of more high-impact activities.

By and large, the available scientific evidence shows that physical activity is desirable and even necessary for bone health. Children who run, hop and play develop thicker, stronger bones than those who remain sedentary, as do teenagers and young adults who participate in sports involving sprinting and leaping.

Most scientists agree that these kinds of activities build skeletal strength by generating sudden, sharp forces that minutely bow or deform the affected bones. Such activities jump-start processes within the body that increase the number of bone cells and help to prepare those parts of the skeleton to withstand similar forces in the future.