A recent study by Strope et al in the American Journal of Mens Health looked at the question of bone mineral density (BMD) and its condition related to the absence or presence of high impact loading (exercise on ground). This is an important question for the bicyclist. Bicyclists are increasing their presence in the research world as having poor BMD of hips and lumbar spine.
This study retrospectively evaluated historical and current exercise in 203 males (30-65 years of age). They found that males who had regular bone loading in adolescence and as a young adult (19-29) had greater lumbar spine BMD than those who had minimal bone loading during this time. They also found that men who continually exercised had greater BMD at hips and spine when compared to their non-loading peers.
So back to our endurance bicyclists, people who only ride bicycles for exercise are being found to have lessening bone density when compared to their age-similar peers. According to this research paper, it is possible that riding a bicycle (avoiding regular impact loading) regularly, starting as a teen until the retirement age in bicycle racing (>/= 35yr old), could result in lower bone density.
Here is the additional sick thing—I am sure there is someone out there doing the math—if my bones are lighter (less dense), that means I will be able to climb faster. True, lighter bones means you will climb faster. Lighter bones also means bones will break much easier when challenged. Bone fractures are an inconvenience for the young. Bone fractures in the elderly population often become a matter of life and death. Bone density and bone health is sort of like financial investment. Early, often investment in bone health helps ensure you will have healthier bones later in life. Late in life investment strategies frequently don’t work.
Of course there is a balance. Too much loading of bony structures can result in early degenerative changes to joints and/or stress fractures. Finding the balance in exercise is critical. The bicycling athlete who is concerned about maintaining healthy bone density should consider the inclusion of impact loading exercise, such as running, ultimate frisbee, or soccer.
Could the maintenance of healthy bone density be as simple as the inclusion of high impact exercise loading? It might, and it’s worth considering.
Strope MA, Nigh P, Carter MI, Lin N, Jiang J, Hinton PS. Physical Activity-Associated Bone Loading During Adolescence and Young Adulthood Is Positively Associated With Adult Bone Mineral Density in Men. Am J Mens Health. 2014 Sep 18. pii: 1557988314549749. [Epub ahead of print]