Osteoporosis and Exercise
By Paul Sorace, M.S., RCEP(sm), CCS
Clinical Exercise Physiologist
Hackensack University Medical Center Pathophysiology
As we age, we all experience some bone loss through the years. The activity of bone forming cells begins to decrease around 35 years of age. Bone remodeling still occurs but the resorbing activity is greater than the forming activity. This will cause a steady decrease (0.5%-1% per year) in bone mineral density (BMD). A reduced total BMD is called osteopenia. Once bone loss becomes so significant that minor falls cause fractures, the condition of osteopenia becomes osteoporosis. A bone scan (I.e.-DEXA) will diagnose osteopenia or osteoporosis. The most common fracture sites are the hip, lower (lumbar) spine, and the wrist. Although men do get osteoporosis, it is considered a woman’s disease.
There are essentially two types of osteoporosis. Type I usually sets in between the ages of 50-75. The presumed mechanism is an estrogen deficiency, which usually occurs with menopause. This reduction in estrogen causes an acceleration in the loss of BMD. Type II usually occurs after the age of 70 and seems to be caused primarily by a vitamin D deficiency and secondary hyperparathyroidism.
- 1. Female gender
2. Caucasian \ Asian race
3. Positive family history
4. Advanced age
5. Premature menopause
6. Prolonged premenopausal amenorrhea
7. Nulliparity (never bore children)
8. Low body weight
9. Lack of physical activity
10. Chronic smoking
11. Excessive alcohol \ caffeine consumption
12. Low calcium intake
While there is no consistent evidence that exercise alone will increase bone mass in individuals with osteoporosis, there is significant evidence that exercise can slow and even halt the loss of bone mass with age and possibly prevent osteopenia from becoming osteoporosis.
Along with losing bone mass through the years, we also lose muscle with age. This is accelerated with physical inactivity. As our muscle tissue decreases, there is less muscle pulling on our bones and the “use it or lose it” theory takes place. Since there is less stress on the bones, our bones lose mass due to the reduced need for extra mass. Strength (weight) exercise will increase muscle mass and this in turn stimulates our bones to increase or maintain the existing level of mass.
People with osteoporosis, many times become inactive due to the fear of falling and fractures. This sets off a vicious cycle. The lack of physical activity accelerates the decline in bone mass and also increases the risk for heart disease.
A complete exercise program, along with a proper diet, can prevent osteopenia from becoming osteoporosis. It can also stop osteoporosis from progressing. There is even some evidence that some individuals, who are on hormone replacement therapy, have experienced an increase in bone density with exercise. Exercise will also condition the heart and lungs to reduce heart disease risk.
Program Design \ Exercise Prescription
The goal of the exercise program should be to increase BMD during and shortly after growth spurts, maintain BMD in adults, and improve balance to promote fall prevention. This way, there will be fewer incidents of falls, fractures, and BMD loss from physical inactivity.
Medical clearance from a client’s physician is required before initiating an exercise program. The program should be well balanced and include both aerobic (preferably weight bearing) and weight training exercises. Cardiovascular exercise should be performed at least 3x per week for a minimum of 20-30 minutes with an intensity inside of their appropriate training zone. The treadmill or walking is a great mode to use since it is weight bearing. Recent research has shown that walking provides a sufficient stimulus on bone to maintain BMD in certain individuals. Caution should be used however with the treadmill. If an individual has experienced vertebral fractures in the past, their center of gravity and balance may have been altered. Holding on the handles or rails may be a good precautionary measure to prevent a possible fall.
Passive, static and PNF stretching is recommended to maintain and increasing joint flexibility and range of motion. Stretching should occur after an aerobic warm-up and the major joints of the body should be emphasized.
Weight training for osteopenia \ osteoporosis works best with a “heavy” weight for 8-12 repetitions per set. Exercises should be used that emphasize the hips, thighs, lower back, and torso. Exercises to strengthen the hip abductors and knee extensors should be included. Increased muscular strength in these areas has been shown to increase lateral stability. This will, in turn, promote better balance and reduce the risk of falling. Exercises that involve trunk flexion (I.e.- ab crunches) should be avoided since this movement increases the likelihood of compression wedge fractures in the lumbar spine. Exercises that incorporate spinal stability should be used to promote proper posture and a neutral spine.
It is important to note that strength exercises performed in a seated position (except hip abduction) have little effect on BMD in the hip (femoral neck). A leg press has actually been shown to have a greater impact on the lumbar spine than the femoral neck. Incorporate, whenever possible, lower body exercises in a standing position. Wall squats is a good exercise since balance can usually be maintained.
Water exercise, although not as effective on BMD as weight training and walking, can be used as an alternative. It essentially eliminates the risk of falling and is effective for aerobic conditioning, which will reduce heart disease risk.