Although we tend to associate brittle bones with women older than age 65, it can also occur in men. And you don’t have to be “old” to experience it. When my son, Dirk Friel, was 29 (he’s now 40) he was tested for bone health at the University of Colorado by Alan Lim, now the exercise physiologist with team RadioShack, and was told that some his bones were like those of a 60-year-old man. Brittle. Interestingly, he had been training for road bike racing since he was 12. As he became older and moved into the pro ranks he did less and less physical activity other than ride a bike. Could riding a bike have contributed to his poor bone mineral density? If so, is this a problem for road cyclists in general? The answer to both questions appears to be "yes."
Bone mineral density (BMD) is a measure of how much mineral, such as calcium, you have in your bones. It is most commonly measured in a selected bone by using a DEXA (dual energy x-ray absorptiometry) scan. There are other methods also used. The results of such testing are scored for risk of a broken bone in a fall or other sudden impact. Those at the highest risk are termed “osteoporotic.” An early stage of osteoporosis is called “osteopenia.”
In recent years there have been a number of studies showing that osteoporosis and osteopenia may well be associated with riding a bike. A quick check of PubMed found the following recent studies, most of which seem to support this possibility. There are some very interesting conclusions here for road cyclists, mountain bikers, triathletes and runners. Following the citation for each study is the quoted conclusion from the authors followed by my comments.
Nichols JF, Rauh MJ. 2011. Longitudinal changes in bone mineral density in male master cyclists and nonathletes. J Strength Cond Res 25(3):727-34.
STUDY CONCLUSION: “The high percentage of male master cyclists with low BMD, combined with a high risk for fracture from falls associated with competitive cycling, warrant attention among this population. Coaches and health professionals interacting with cyclists need to promote alternative exercise such as weight training, plyometrics, or other high impact activity as a complement to cycle training to help minimize bone loss in this population.”
COMMENTS: This study followed 19 competitive road cyclists and 18 non-athletes for 7 years. All were over 35 years of age. At the start of the study 84% of the cyclists met the criteria for osteopenia or osteoporosis (50% of the non-athletes). Seven years later 90% of the cyclists had osteopenia or osteoporosis (61% of non-athletes). Of the 19 cyclists 6 became osteoporotic during the 7 years.
Campion F, Nevill AM, Karlsson MK, Lounana J, Shabani M, Fardellone P, Medelli J. 2010. Bone status in professional cyclists. Int J Sports Med 31(7):511-5.
STUDY CONCLUSION: “Professional cycling appears to negatively affect BMD in young healthy and highly active males, the femoral neck being the most affected site (-18%) in spite of the elevated muscle contractions inherent to the activity.”
COMMENTS: Compared with amateurs, pro road cyclists probably spend less time walking, running, lifting weights or doing other things that encourage bone growth as they are highly focused on recovery and staying off of their legs after workouts.
Wilks DC, Gilliver SF, Rittweger J. 2009. Forearm and tibial bone measures of distance- and sprint-trained master cyclists. Med Sci Sports Exerc 41(3):566-73.
STUDY CONCLUSION: “Sprint cyclists and to a lesser extent distance cyclists had greater tibia and radius bone strength surrogates than the controls, with tibial bone measures being well preserved with age in all groups. This suggests that competition-based cycling and the associated training regime is beneficial in preserving average or above-average bone strength surrogates into old age in men.”
COMMENTS: This is the only study I’ve found which shows that competitive road cycling preserves bone mineral density in cyclists.
Smathers AM, Bemben MG, Bemben DA. 2009. Bone density comparisons in male competitive road cyclists and untrained controls. Med Sci Sports Exerc 41(2):290-6.
STUDY CONCLUSION: “Our findings indicated that male cyclists had lower spine BMD than controls, which was not associated with group differences in testosterone.”
COMMENTS: Despite a higher calcium intake by the road cyclists, 9% of the cyclists and 3% of non-athlete controls who were age-matched with the cyclists were classified as osteoporotic, whereas 25% and 10% of cyclists and controls, respectively, were osteopenic. I’ll come back to this calcium-intake oddity in the next post.
Medelli J, Lounana J, Menuet JJ, Shabani M, Cordero-MacIntyre Z. 2009. Is osteopenia a health risk in professional cyclists? J Clin Densitom 12(1):28-34.
STUDY CONCLUSION: “In conclusion, two-thirds of professional cyclists had abnormally low BMD values.”
COMMENTS: 23 professional male road cyclists aged 28.5 (+/- 3.9) years were tested for BMD of the lumbar spine (lower back), arm and leg. Climbers had the lowest arm BMD and time trialists the highest spine BMD. Most were at least osteopenic.
Barry DW, Kohrt WM. 2008. BMD decreases over the course of a year in competitive male cyclists. J Bone Miner Res 23(4):484-91.
STUDY CONCLUSION: “This study suggests that high intensity cycle training may adversely affect BMD. Excessive dermal calcium loss during exercise may be a contributing factor, but mechanisms remain to be elucidated.”
COMMENTS: 14 male road cyclists, 27-44 yr of age, were tested for BMD over the course of a year including bicycle training and racing. For one year some took in 1500mg of supplemental calcium citrate daily while others took in 250mg daily. BMD was found to decrease significantly in the hip and femur (thigh bone) of the subjects. There was no difference in BMD between the two groups regardless of how much calcium they consumed. (Again, more on this in a later post.) The authors believe the cause may be a loss of calcium in sweat. This seems doubtful given that runners also sweat heavily but don’t lose hip or femur BMD as cyclists do.
Nichols JF, Palmer JE, Levy SS. 2003. Low bone mineral density in highly trained male master cyclists. Osteoporos Int 14(8):644-9.
STUDY CONCLUSION: “These data indicate that master cyclists with a long history of training exclusively in cycling have low BMD compared to their age-matched peers. Although highly trained and physically fit, these athletes may be at high risk for developing osteoporosis with advancing age."
COMMENTS: Three groups of men were studied: 27 older road cyclists (51.2+/-5.3 years); 16 young adult road cyclists (31.7+/-3.5 years,); and 24 non-athletes matched by age (+/-2 years) and body weight (+/-2 kg) to the older cyclists. All of the cyclists had been training and racing for at least 10 years. Otherwise, they engaged in little or no weight-bearing exercise. The non-athletes were “normally active” (which I take t mean they did little or no exercise). BMD of the lumbar spine and hip was significantly lower in the master cyclists compared to both the non-athletes and the young adult cyclists. Among the older cyclists weight-bearing exercise performed during teen and young adult years did not appear to influence BMD by the time they were in their late 40s.
Warner SE, Shaw JM, Dalsky GP. 2002. Bone mineral density of competitive male mountain and road cyclists. Bone 30(1):281-6.
STUDY CONCLUSION: “Higher BMD in the mountain cyclists suggests that mountain cycling may provide an osteogenic stimulus that is not inherent to road cycling.”
COMMENTS: Three groups were studied: 16 competitive mountain bikers, 14 competitive road cyclists and 15 recreationally active men (control group). BMD was significantly higher at all sites in the mountain cyclists compared with the road cyclists and controls. Mountain biking may not have as deleterious an effect on BMD as road cycling. The study also suggests that it may be more beneficial than being “recreationally active.” This may be due to the need to dismount and run with, and perhaps even carry, the bike over challenging sections on the course.
Stewart AD, Hannan J. 2000. Total and regional bone density in male runners, cyclists, and controls. Med Sci Sports Exerc 32(8):1373-7.
STUDY CONCLUSION: “Running is associated with increased bone density, particularly in the leg, whereas cycling is associated with a mild decrease in bone density in the spine. In athletes who do both, running exerts a stronger influence than cycling.”
COMMENTS: Male athletes who were runners (N = 12), road cyclists (N = 14), or both (N = 13) were compared with non-exercising, age-matched controls (N = 23) for BMD. All athletic subjects had competed for a minimum of 3 years and trained for a minimum of 4 hours per week. Runners did no cycling and cyclists did no running training. Compared with the controls, runners had a greater total body and leg BMD, cyclists had reduced spine BMD, and athletes of the "both" group had greater total body and arm BMD. Essentially, running, even if mixed with cycling as with triathletes, seems to maintain or even improve BMD.
In a coming post I’ll get into what the research seems to be saying about how to maintain BMD. I think this is especially important for road cyclists. Hopefully, time will permit me to get at this later in the week. We’ll see.