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Written by Tom Lambert
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Tuesday, 09 May 2006 |
So my brainiac sister keyed me into the subject of cycling and bone density issues that she heard in a class up at UMO. Her initial comment that got me interested was "there was a recent study that found that endurance cycling can actually reduce your bone density". Having high bone density is beneficial, especially in the later part of your life when you become a bit more frail. Well, it turns out it is pretty difficult to gain bone density at later ages because at a certain age your body doesn't have the ability to assimilate calcium into building bone/increasing density. Eating more calcium only helps you maintain what you have. To build bone density you need to exercise, and apparantly you need to do certain types of exercise that include weight bearing and/or have higher impacts.
Now I knew that weight lifting and running were known to increase bone density at least in certain bones of the body, but I was unaware that cycling can actually cause your bone density to decrease. So I decided to do a little research considering I have access to the primary research literature through the university. The disclaimer here is that I know nothing about bone density and/or exercise physiology, so I do my best to say only the obvious findings that are more than less unquestionable.
I found several key papers, but really only read one fully. Warner et al. published a study in Bone in 2002 called "Bone Mineral Density of Competetive Male Mountain and Road Cyclists". looking at bone density differences between pretty serious road cyclists, mountain cyclists, and a non-cycling control group. In summary, they found that the road cyclists were slightly lower bone density (statistically insignificant) than the controls, but the mountain cyclists had statistically signficant higher bone density over the road cyclists and control group. This means that the impact/jarring of mountain biking has some beneficial effect to bone density that road cycling does not offer.
Warners cited literature talked of previous studies that found bone density deficiencies in road cyclists, even a study covering Tour De France cyclists who were 17% below the controls (Sabo, 1996). Yikes!!!! Also, another study showed that you put more weight on the pedals mountain biking because you are standing more (up to 70% of your weight while standing), whereas sitting on a road bike at 250 watts puts less than half of your weight on the pedals (that number is somehow weight controlled I'm sure). Some of the other absracts I read said that some of these road cyclists were borderline osteoperotic at really young ages.
What can you do if you think you have bone density issues or are concerned? Do a little research for yourself on Google and find out. It's a pretty popular topic. I did a quick search and found plenty including eating more calcium and doing more weight bearing exercise.
On a side note that may fuel arguments between mountain bikers and roadies for more time to come, Warner also found mountain cyclists have insignificantly higher levels of testosterone!!!! But how come? Is it a chicken-egg issue? Is testosterone higher in mountain cyclists because mountain biking MAKES you produce testosterone? Or do people with higher testosterone prefer mountain biking more than road biking? Maybe mountain bikers ARE more manly than road cyclists! Maybe lycra squeezes your testosterone out, or shaving messes with you! Well, that is only true if you think having more testosterone makes you more manly. There are some in the crowd that certainly think more testosterone certainly makes you dumber!
Don't trust me, read for yourself:
Warner et al. 2002, Bone Mineral Density of Competetive Male Mountain and Road Cyclists, Bone, volume 30 issue 1
Sabo et al. 1996, Bone quality in lumbar spine in high-perormace athletes. European Spine Journal, volume 5 p258
Other references can be found within the references of these papers.
Tom |
