A silent epidemic is raging in America: weak bones. There are two terms used to describe this condition. "Osteopenia" refers to detectable bone thinning; "osteoporosis" describes severe bone mineral loss-a disease that sharply raises the risk for serious fractures as we age. Although we tend to think of osteoporosis as a disease affecting older women, it commonly involves men as well. In fact, after age 50, osteopenia or osteoporosis affects not only one in three women, but also one in 12 men.
Like most other organ systems in the body, bone mass begins to decline with age. This should be a major consideration even for young people, who need to recognize the problem they'll eventually confront. Of course, it isn't an easy message to communicate to a 20-year-old whose immediate thoughts aren't about menopause, loss of estrogen, calcium depletion, and crumbling bones. Just as in childhood, bone health in adulthood depends on a combination of genetics, good nutrition, hormones, sunlight, and mechanical stress or use. That's right, use. When bones are stressed, they adapt, grow, and become strong. When they're not asked to do their load-bearing job, they quickly become weak and frail. Disuse is deadly to a healthy bone.
Numerous studies have shown that during prolonged periods of disuse-for instance, in patients on medically necessary bed rest or astronauts living or traveling in space without gravity-the bones weaken markedly and become thinner. Granted, these are extreme and unusual situations, but the same thing, in less dramatic fashion, happens day after day, year after year to otherwise healthy adults who adopt a sedentary lifestyle.
Dozens of medical studies have demonstrated the clear benefits to bone health that result from strength training-increased bone density in the hips, low back, and arms; dramatic gains in muscle strength; and substantial improvement in dynamic balance. Together, these benefits add up to fewer falls and broken bones. Research also shows an improvement in bone mineral density is less from activities such as walking, jogging, and aerobics. In addition, bone density improvements from these activities occur primarily in the low back, less in the hips, and hardly at all in the arms and shoulders.
In addition, one study published by the American Medical Association states that a twice a week strength training program provides more benefits to the bones than estrogen-replacement therapy in terms of decreasing the risk for osteoporotic fractures. Researchers further conclude that lifting light weights doesn't increase bone density any more than the recreational activities listed above. Therefore, one must perform strength training with enough poundage to stimulate muscle growth.
When young adults take up strength training, they're taking out an insurance policy for their later years. A properly performed strength training regimen brings about better-sustained bone density gains in men and women of all ages-even those in their 80s and 90s-than any other form of exercise. Remember, stronger muscles mean stronger and harder bones. IBI