The milk industry has become well known for its “Got Milk?” advertisements that feature famous athletes with a characteristic “milk mustache.” The calcium and Vitamin D found in milk is thought to help strengthen the bones of those that exercise (also the bones of those that don’t). However, recent research suggests that the bones of all athletes are not created equal.
If you’re looking for reasons to start a regular exercise program, here’s another. Like other tissues in the body, bones need a little stress to help maintain their strength. With too little stimulation bones can begin to become thin and fragile. Exercise, and in particular weight bearing exercise, has long been thought to improve bone density and most physicians recommend this type of exercise to those at risk for lowered bone density. Women are at increased risk of low bone density, known as osteopenia or osteoporosis, later in life. But consider this; not all weight bearing exercise has the same effect on bone density.
For instance, the research shows that swimmer Michael Phelps needs more than a glass of milk to make his bones strong. Swimmers and cyclists, whose sports do not include weight bearing or impact, don’t stimulate their bones to stay strong. Interestingly, mountain biking has been shown to be more beneficial for bone density than road cycling because of the repetitive jarring and vibration of the sport.
However, what may be surprising to many is that even the most jarring endurance activity of all, running, may not stimulate bone density as much as ball sports like basketball or soccer. Researchers hypothesize that the repetitive moderate intensity impact of endurance running does not stimulate bone formation as much as the higher intensity, varied angle impact of ball sports. The take home point is not starting your grandparents on a soccer program but rather that varying the type and intensity of impact exercise is a key facet of strengthening bones.
As the milk ads suggest, nutrition does play a role in bone density. Age and gender appropriate levels of calcium and Vitamin D are important factors in keeping bones strong. Nutritional researchers also point to the calcium lost through sweat as a significant factor for all that enjoy exercise. Any significant amount of calcium lost through sweating is replaced by calcium from bones. Nutritionists suggest that fortifying with a 1000-mg calcium supplement prior to exercise may prevent the body from leeching calcium from bones during sweaty exercise, especially for those at increased risk of low bone density. Additionally, as skinny and slender athletes are at risk for low bone density and it’s associated risk of stress fractures and osteoporosis, eating a sufficient amount of calories is important for good bone health.
Orthopedically, this means that runners, swimmers and cyclists should consider mixing in a little soccer, basketball or aerobic class at the gym. Changing it up might keep bones strong and fracture resistant now and in the future.