Cycling Bone Loss: Cycling, Stem Cells, and Bone Mass?
Could cycling bone loss exist? When I first saw this study in 2009, that seemed to indicate that competitive cyclists had poor bone density, I wasn’t sure what to make of it. The study showed that 25% of competitive cyclists were classified as “osteopenic” (weak bones). Well, after two more years of performing bone marrow aspiration procedures with knowledge of the study, I would have to say the study is accurate. Every middle aged male I’ve had on the table whose stem cell harvest was just too easy, when asked about primary source of exercise, states that it’s cycling.
A bone marrow aspiration (harvest) for a stem cell procedure is the ultimate bone density test. In the procedure (which is very different than a bone marrow biopsy) a needle is worked through the bone at the back of the hip and what looks like a thick blood sample (where the stem cells live) is pulled out into a syringe. As a result, the doctor has an immediate sense of bone density, as in the usual healthy male the needle will require some pressure (bone isn’t like cement, but hard plastic).
Why would cyclists have lower bone density? It’s likely because of the “use it or loose it” stem cell principle. We have stem cells throughout our bodies and also in our bones. When the bones are challenged by weight bearing exercise like walking, jogging, and weight lifting, the adult stem cells spring into action to shore up the bones under stress. However, if your primary source of exercise involves pressure and stress only on the legs and nowhere else, your leg bones will be strong with active stem cells making more bone, but the other areas where we measure for osteoporosis (like the spine) will be weak. In essence, you’re only activating stem cells in certain bones.
The upshot? If you love cycling like many of our compatriots do here in Boulder, Colorado, mix in some weights!