Advice on Foot Care

Bone is composed of minerals, protein and living cells. Calcium and phosphate form an extremely hard crystal-like structure called hydroxyapatite. The protein collagen forms an intricate network of strong fibrous bands to which the crystals attach. The combined properties of the hydroxyapatite and the collagen create the amazing strength of bone. Osteoblasts and osteoclasts are responsible for the breakdown and build-up of bone, a process is referred to as bone remodeling. When the rate of breakdown exceeds the rate of build-up, bone becomes less dense, lighter and weaker. Natural bone loss starts around age 30 and is accelerated during menopause for women.

Weight bearing exercises, such as walking and jogging and strength exercises, such as weight lifting are known to increase bone strength. Bone responds to physical stress by increasing the natural remodeling process and increasing bone density. The direct impact on bone from walking or running, as well as the tension placed on bone from the muscles during physical activity, stimulates bone remodeling, increasing bone density. Cycling is a low impact activity and although it can be strenuous, it does not place the same type of mechanical stress on the bone as activities such as weight lifting. Cycling has been associated with osteopenia and competitive cyclists in their 20s and 30s have been known to suffer from hip or leg fractures, which would normally only occur in the elderly population.

Bone strength can be measured with a bone mineral density test. This test measures the amount of minerals in the bone. A recent study evaluated bone mineral density in 32 male competitive road cyclists and compared the cyclists to 30 men the same age and with the same body type. The researchers found the male cyclists had lower bone mineral density than their age-matched controls, despite a higher calcium intake. A study earlier this year evaluated bone mineral density in professional cyclists and found 66% of professional cyclists had abnormally low bone mineral density values.

Another recent study evaluated bone mineral density in three types of sports, endurance running, endurance cycling and resistance training. The researchers found that resistance training athletes and endurance runners had much greater bone mineral density than endurance cyclists.

A study in Osteoporosis International evaluated bone mineral density in young adult competitive cyclists (average age 31 years) and older competitive cyclists (average age 51 years) and compared them to age-matched controls. The cyclists engaged in little weight bearing leisure activity. Both groups of cyclists had lower bone mineral density than their age-matched controls and the older cyclists had lower bone density than the younger cyclists. The authors concluded that competitive cyclists who engage in little leisure time weight-bearing exercise may be at high risk for developing osteoporosis as they age.

Mountain cyclists fair better than road cyclists. A study compared the bone mineral density of competitive road cyclists and competitive mountain cyclists to a group of recreationally active men. Bone mineral density was higher in mountain cyclists than in both the road cyclists and the control group. They authors suggested that the impact of mountain biking on the body may provide a stimulus to the bone, increasing bone mineral density.

The research supports the idea that competitive road cyclists of all ages have weaker bones and may be at risk for osteoporosis and fractures with advancing age. Competitive cyclists do little leisure time impact activity and tend to avoid weight lifting, to minimize excess muscle mass. Competitive cyclists are a unique group and the research does not suggest that recreational cyclists have the same risk.

1. Smathers AM, Bemben MG, Bemben DA.  Bone density comparisons in male competitive road cyclists and untrained controls. Med Sci Sports Exerc. 2009 Feb;41(2):290-6.
2. Rector RS, Rogers R, Ruebel M, Widzer MO, Hinton PS. Lean body mass and weight-bearing activity in the prediction of bone mineral density in physically active men. J Strength Cond Res. 2009 Mar;23(2):427-35.
3. Nichols HF, Palmer JE, Levy SS. Low bone mineral density in highly trained male master cyclists. Osteoporosis International. Volume 14, Number 8 / August, 2003.
4. Medelli J et al.  Is osteopenia a health risk in professional cyclists? J Clin Densitom. 2009 Jan-Mar;12(1):28-34.
5. Shaw JM, Dalsky, GP. Bone mineral density of competitive male mountain and road cyclists. Volume 30, Issue 1, Pages 281-286 (January 2002).

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