Bone Loss in Cyclists

On January 30 the New York Times published a story “Can Low-Impact Sports Like Cycling Be Putting Your Bones at Risk?”. It refers to a Norwegian study that compared DXA scans of twenty elite runners vs. 19 elite cyclists. It concluded that the cyclists had significantly lower Bone Mineral Density (BMD) compared to the runners despite having similar calcium intake. One cyclist had osteopenia and another ten had BMD more than one standard deviation below the norm, despite most of the cyclists performing weight training as part of their training (weight training has been shown to build bone).

Note that most of the cyclists were in their 20’s and trained 900 hours per year (17 hours per week), so most of us don’t have to worry about being in this cohort, although the study authors did add a comment that “a higher prevalence of osteopenia and osteoporosis has been displayed in highly trained master cyclists” (90%). One commenter in the article noted that significant calcium loss can occur because of sweating. The study authors referenced another study that suggested a “calcium-rich meal 90 min prior to intensive exercise”. Note that elite cyclists have a unique focus on low BMI (or high watt/kg) that might skew the results. The study authors conclude “it raises the question whether interventions to increase BMD in this population should be considered”.

The study was small and the NYT did a disservice by raising FUD (fear, uncertainty and doubt) without putting the study in context or offering solutions. Low BMD does not necessarily mean low bone strength. Trainer Road emphasizes good nutrition and appear to be fond of DEXA scans (that determines, among other things, bone density), but are there other studies that we should know about or should the 4 watt per kilogram crowd be concerned?

I recently had a dexa scan and my BMD was quite good while I had an extremely low fat%

Its fairly well accepted that cycling does nothing for bone density as its not weight bearing.
What I did find surprising though is that MTB’ing IS weight bearing.
Running is also weight bearing so it doesn’t need to be weight lifting, as are body weight exercises.
As we age it becomes more important to be aware if bone density.
You might have seen the video clips of Sagan doing his gym workouts so the elite know the importance of core and weight bearing exercises.

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Mix in some mountain biking.

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I didn’t read the entire OP but going to the gym and doing weight work is a good way to offset. In fact, this has been covered in several AACC podcasts.

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You also have to consider diet in this equation. If you don’t keep your blood slightly alkaline (generally through a plant based diet) , the body will leach calcium out of your bone marrow to help reduce the acidity of the blood to get to the desired PH balance.

Those athletes are getting almost no vitamin D year round. I want to see this study replicated where the athletes are doing the same volume, but they have sufficient levels of vitamin D, which is thought to help with calcium absorption.

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In addition to spending a lot more time training than average, elite cyclists will also tend to spend a lot more time resting. And they’ll often take this rest very seriously - literally putting their feet up.

All this time - training and resting - has the potential to add up such that the rider spends very little time at all in weight bearing activities. Cycling’s unlikely to have such a dramatic effect on the average cyclist’s schedule and lifestyle.

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