Bulk Up Those Bones
Even a little jogging helps men strengthen their bone density, says study
TUESDAY, July 3, 2001 (HealthDayNews) -- Men, give your bones a run for their money. Jogging not only improves the density of your bones, but it helps keep you from breaking your hip down the road, a new study says.
Only don't go too far. The study also found that if a man jogs at least 20 times a month, his bone density is no better than those who jogged less frequently. That may mean that there's a limit to the effects of jogging on bone density.
Although 80 percent of Americans who have osteoporosis -- a dangerous thinning of the bones -- are women, upwards of 2 million men are affected, according to the National Institutes of Health. The disease, which has no symptoms, is marked by loss of bone mass and increased risk of spine, wrist and hip fractures.
"Most of the previous research on bone mineral density (BMD) focused on women," says Michael E. Mussolino, the study's lead author, a researcher with National Center for Health Statistics, which is part of the Centers for Disease Control and Prevention.
The research team analyzed data on more than 4,200 men between the ages of 20 and 59 who took part in the large-scale national Third National Health and Nutrition Examination Survey (NHANES III), between l988 and l994. Of that group, 954 were joggers, more than 2,7000 didn't jog but did some other form of physical activity, and the rest didn't exercise at all.
The bone mineral density of the femur, or thighbone, was compared in those who jogged and those who didn't, and the researchers found that the mean femoral BMD was 5 percent higher among joggers than among non-joggers. The study didn't report how many miles the joggers covered.
There was also a significant difference in BMD between those who jogged fewer than eight times a month and those who jogged at least nine times a month, says Mussolino. But even those who jogged less had a higher BMD than non-joggers, he adds, which suggests "even infrequent jogging may be beneficial."
Included in the analysis were smoking status, alcohol consumption, calorie and calcium consumption, protein intake, weight history and chronic conditions related to osteoporosis. Researchers did not, however, compare the BMD figures from the study to any established norms.
"We may have something of public health significance because low bone mineral density is a predictor of hip fracture," says Mussolino. But, he notes the study, "cannot provide definitive evidence that jogging caused the higher BMD levels."
Dr. Carlos M. Isales, an endocrinologist at the Medical College of Georgia, says men need to be concerned about osteoporosis. "Seven to 13 million men are at risk," he notes. "But, since men have higher peak bone mass, and start at a higher point, it takes them longer to reach the levels where the fractures occur."
Men reach their peak bone mass at about age 25, then gradually lose bone density as they age, says Isales.
So it's never too early to take preventive measures. "Things like nutrition impact bone density. We tend to eat diets low in calcium and nutrients, and it takes its toll, " Isales says.
The study appears in the current issue of American Journal of Public Health.
What To Do
"We realize not everyone's skeleton is right for jogging," says Mussolino. Bad backs and bad knees may not make it the sport of choice. But, he adds, any "weight-bearing exercise where the hip area is directly loaded" is good.
Isales agrees. "Lifestyles and common sense changes are important." If you're a smoker, quit. Make sure you eat a balanced diet and get plenty of exercise. And, if jogging's not for you, try "walking one hour a day, five days a week."
Learn more about bone mineral density from the National Osteoporosis Foundation.
Learn more about keeping your bones healthy in the bone health resource center of the National Institutes of Health.