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In the wake of the column comparing elliptical training to running, I got a very interesting e-mail from Gary Rothbart, a Toronto personal trainer. He said, in part:
I feel that the fitness community has done a great disservice to the average person. One of the most important factors with respect to avoiding osteoporosis is high impact activities… The difference between running and the use of non-impact machines is great when taking into the long term implications on bone density.
That makes a lot of intuitive sense. To be honest, that’s something I expected to find when I started researching this story — but I didn’t. That doesn’t mean it’s not true, but I wasn’t able to find solid evidence that it is. One point worth noting is that the elliptical is still very much a weight-bearing activity, even if jarring impacts are reduced. In this article from the Washington Post from a few years ago, a scientific advisor to the U.S. National Osteoporosis Foundation makes that point:
[…] A workout on an elliptical machine provides no-impact, weight-bearing exercise: While your bones are supporting your weight, your feet are not striking the ground, as they do when you walk or run. So are you missing bone benefits by giving up the impact? If so, not much, [Creighton University professor Robert] Recker said. The bone density benefit from an elliptical machine workout is comparable to that from a run of equal time.
As far as I can tell, he’s drawing that conclusion from an absence of research, rather than specific studies showing it to be true. There is, however, some relevant research on bone density that I came across while researching an upcoming piece for Canadian Running. According to this article from the current issue of Medicine & Science in Sports & Exercise, “Generally, strength- and powertrained athletes have higher BMD [bone mineral density] than endurance-trained athletes, and male long-distance runners have been reported to have lower BMD than controls.” I followed up the references, and found several studies dating as far back as the 1980s confirming that serious runners seem to have lower bone density than sedentary people. The mechanism for this still isn’t understood.
So what can we conclude from all this? It’s still hard for me to believe that running isn’t a bit better for bone density than alternate activities like the elliptical — though, as a runner, I may be biased. But given the mixed messages above, I don’t feel we’re at a point where I could recommend against using the elliptical for bone density reasons. Of course, there may well be other research out there that I missed. If so, please let me know!