The Conundrum Of Modern Endurance Cyclists

Jason in his quest for endurance in mountain bicycling has stumbled upon an area in bone health that should concern all health care and sports medicine practitioners. And of course, the athletes themselves.

Studies have shown that endurance sports athletes in running, biking and swimming often have lower bone density than those who participate in ball and power sports, Rarely they can have bone density that is lower than their inactive peers.

This is the conundrum.

Is this due to a selection bias in athletes as they usually have lean body mass? Lean body mass may translate to lower bone density scores on DEXA imaging. It is known that this translates eventually to more fractures in their lifetime

Is low BMD in endurance athletes preventable?

Other mechanisms of low bone density noted maybe related to energy deficits in athletes, hormonal changes, loss of calcium 

Do the diet and nutrition have a role to play in these athletes? Is it enough to improve caloric nutrition? Or are calcium and vitamin D supplements required?

One of the mechanisms is indeed thought to be the calcium lost in sweat.  And the subsequent rise on parathyroid hormone during prolonged cycling. This is “acute bone resorption”. Does the ingestion of calcium immediately before or during cycling help prevent these changes?

Is a stress fracture that is commonly seen in athletes a cause for concern?

Do stress fracturs in an athlete translate to increased fractures later in life?

Are adolescent athletes spared the ill effects or are they particularly susceptible to factors due to growing and maturing skeleton?

Can loading forces on bone be optimized with cross training? Is triathlon where there is cross training healthier for bone?

When should such an athlete have their first bone health consult and BMD screening?

These are among the many unanswered questions in the arena of bone health.

In the meantime, it is recommended that endurance athletes of all ages should be evaluated for risk factors. Investigations maybe warranted.

Remedial training programs (high-impact cross training) to improve strength of bone and improve energy needs maybe instituted when high risks factors are identified.

L. Myneni MBBS,FACP,FACR
Rheumatology, Immunology and Bone health.