The most-feared injury among serious bicyclists is a broken hip. The femur hip bone is shaped like a shepherd's crook. The blood supply to the ball at the top of the hip bone comes in through the neck just below the ball. If the neck or ball are broken, the blood supply is usually shut off and the top of the hip bone dies. To prevent this from happening, fractures of the ball or neck of the hip bone are usually treated with immediate hip replacement. Try to avoid this drastic surgery by keeping your bones as strong as possible.
1) All exercise strengthens bones. Bicycling strengthens bones, but not as much as sports that exert greater forces on bones such as running or lifting weights. ( Medicine & Science in Sports & Exercise, March 2009).
2) Exercise increases calcium absorption, which is necessary for strong bones. As I reported last week, even non-impact exercises such as swimming and cycling increase calcium absorption from the intestines by upregulating the calcium transporter genes. ( American Journal of Physiology, Endocrinology and Metabolism, April 2009).
3) Those most likely to suffer broken bones during exercise are people who have low levels of vitamin D ( Journal of Bone and Mineral Research, September 2006). When you lack vitamin D, ionizible calcium drops. This causes the parathyroid glands to put out large amounts of parathyroid hormone which takes calcium out of bones to weaken them and increase fracture risk.
4) High blood levels of parathyroid hormone (from vitamin D deficiency or any other cause) are a major risk factor for bone fractures during exercise ( Bone, August 2005).
If you ever are unable to expose a few inches of skin to sunlight for at least 20 minutes four or five times a week, get a blood test called vitamin D3. If it is below 75 nmol/L, you need to take a vacation in a sunny place, or take at least 3000 IU of vitamin D per day until you can get some sunlight.