Osteoporosis is the most common metabolic bone disease in adults. (Hertling, 1990). It is characterized by a low bone mass and loss of bone strength, which leads to fragile and brittle bones and a high risk to fracture. Although this loss of bone in itself does not normally cause symptoms, the associated fracture and collapse of vertebrae can be extremely painful and limiting. Each year, osteoporosis leads to 1.5 million fractures in the U.S. That means that someone suffers a hip fracture approximately every 2 minutes. (Chrischilles et al, 1994). 1 in 3 Americans over the age of 50 (mainly women) will suffer a fracture related to low bone mass. (Cooper et al, 1992). According to the National Osteoporosis foundation, the associated cost of osteoporotic fracture is approximately $10 billion per year.
Our bones are constantly going through a remodeling cycle. Cells called osteoblasts are building up or forming new bone, along with osteoclasts, which lead the process of bone resorption (bone removal). When we are kids and teenagers the rate of bone formation is faster than bone resorption, this leads to an overall gain in bone mineral. As we reach adulthood, this process of resorption occurs at a faster rate than new bone can form. This causes a steady gradual decline in the density of our bones of about 1% per year. (Witzke, 99). This rate can be as high as 3-5% in postmenopausal women. Osteoporosis occurs 9 times more frequently in women than in men.
The three most common sites for fracture with osteoporosis are the spine (vertebral fractures, hip and wrist. Most fractures are the result of a fall, but in the case of a vertebral fracture, it may be something as simple as turning over in bed. The most debilitating of all osteoporotic fractures, is the hip. Which can lead to a loss in independence and even death from surgery or prolonged bed rest. “It is estimated that 50 % of people who sustain a hip fracture due to a fall never become functional walkers again.” (Witzke, 99).
While the exact causes of osteoporosis are not understood, there are factors that can help you determine your potential risk.
1. Genetics: These are things you can’t control, such as: family history, fair complexion, Northern European or Asian descent, small thin frame.
2. Estrogen: This hormone helps to slow the rate of bone resorption. Estrogen deficiency is most commonly seen in postmenopausal women and young, athletic amenorrheic women. Amenorrhea is the loss of a menstrual cycle due to excessive exercise & physical training. Studies have shown that young amenorrheic but otherwise healthy aerobic instructors, have been shown to have the bone density equal to that of a 50 year old women. (Drinkwater et al, 1994). This loss in bone mass has been shown to be irreversible in young women who have gone without their menstrual cycle for as little as 12 months. This puts them at a much higher risk of osteoporosis.
3. Dietary Calcium intake: Calcium is essential for proper bone formation. If you are not getting enough calcium from your diet, then the calcium is pulled from your bones in order to maintain the proper blood levels.
4. Lifestyle factors: All tissues in the body atrophy when they are not used and bone is no exception. The pressure of weight bearing and the stress through our bones from the pull of the muscles actually stimulate new bone formation. (Salter, 1983). If someone is confined to a bed or severely limited in their activities, their bone formation capabilities slow and can’t keep up with the bone resorption rate. This leads to disuse atrophy. The only way to actually increase new bone formation (after maturity) is through skeletal loading.
According to the American College of Sports Medicine, which published a Position Stand on Osteoporosis in 1995, they determined that:
- Weight bearing physical activity is essential for the normal development and maintenance of a healthy skeleton. Activities that focus on increasing muscle strength also may be beneficial, particularly for non-weight bearing bones.
- Sedentary women may increase bone mass slightly by becoming more active, but the primary benefit of the increased activity may be in avoiding the further loss of bone that occurs with inactivity.
- Exercise cannot be recommended as a substitute for hormone-replacement therapy at the time of menopause.
- The optimal program for older women includes activities that improve strength, flexibility and coordination that may indirectly, but effectively, decrease the incidence of osteoporotic fractures by lessening the likeliness of falling. (Whitzky, 1999. ACSM, 1995)
So, in conclusion, there is something that we can do to keep our bones from getting more fragile and reduce the risk of osteoporosis and fractures. Stress our bones…Forceful muscular contractions…Direct impact activities…Jumping…Weight lifting. These activities put force or stress through the bone. Activities such as walking or swimming may be good for balance, endurance and cardiovascular conditioning, they do not sufficiently overload the bone in order to increase bone formation or slow bone loss.
If you suffer from osteoporosis, or are unsure how to safely get started on an exercise program, you may want to see a physical therapist. After you have been given clearance from your doctor, a physical therapist can evaluate your specific needs and start you on an individualized program. Remember, it’s never too late to make a difference.
1. Whitzky, K. (1999). Osteoporosis. Clinical Exercise Specialist Manual. P360-377. San Diego, Calif.
2. Salter, R. (1983). Textbook of Disorders and Injuries of the Musculoskeletal System. Williams & Wilkins. Baltimore.
3. Hertling & Kessler. (1990). Management of Common Musculoskeletal Disorders. JB Lippincott. Philadelphia.
5. American College of Sports Medicine. (1995). ACSM position stand on osteoporosis and exercise. Medicine and Science in Sports and Exercise, 27, 4, I-vii.
6. Chrischilles, Sherman & Wallace. (1994). Cost and Health Effects of Osteoporotic Fractures. Bone, 15, 377-386.
7. Drinkwater, Nilson & Chesnut. (1994). Bone Mineral Content of Amenorrhea and Eumenorrheic Athletes. New England Journal of Medicine, 311, 277-281.
8. Cooper, Campion & Melton. (1992). Hip Fractures in the Elderly; A Worldwide Projection. Osteoporosis International, 2, 285-289.