Osteoporosis, like heart disease, is no longer considered a normal consequence of the aging process. It is predictable, to a large extent preventable, and treatable. Osteoporosis is fairly unique in that it predominately affects women and results in more than one million fractures a year in the United States. Hip fractures alone, lead to approximately 50,000 deaths a year. Over $10 billion are spent annually to treat the aftermath of the disease.
Osteoporosis Means More Than Just Bone Loss
Bonnick1 defines osteoporosis as “a systemic skeletal disease characterized by low bone mass and micro-architectural deterioration of bone tissue with a consequent increase in bone frailty and susceptibility to fracture.” These types of fractures are called fragility fractures and are most common in the hip and the spine. The fractures are not usually do to an injury or accident but are a result of bone being subjected to a forceful blow, as in a fall. This newer definition of osteoporosis has evolved due to the technology in bone densitometry that is able to detect changes in the amount of bone as small as 1.5 percent. A woman is at risk for fracture when she has lost approximately 20 percent of her bone mass. The more bone lost, the greater the risk of fracture.
A 50-year-old Caucasian woman today has a 54 percent chance of having an osteoporosis-related fracture in her lifetime.
What Causes Osteoporosis?
Osteoporosis evolves gradually over the years. The amount of bone you have as a young adult is called your peak bone mass and is subject to many factors that can cause bone loss over a lifetime. A low peak bone mass accentuates the risk for developing osteoporosis later in life. The amount of bone an individual has at peak bone mass is determined by the body’s ability to make bone. Genetics accounts for approximately 80 percent, while nutrition, exercise, illness, and estrogen and life-style factors, such as alcohol use and smoking, determine the remaining 20 percent of one’s ability to generate bone.
A unioque type of cell, the osteoblast is responsible for the break down and reabsorption of bone. This process of bone formation and bone reabsorption continues throughout life. Children and adolescents are continually growing bone until peak bone mass is achieved. At peak bone mass, bone formation and bone reabsorption occurs at equal rates, and remains fairly constant as adults. As we age, bones are affected by wear and tear and must be replaced with new bone. This process is called bone remodeling. Osteoporosis is the result of an imbalance in the bone-remodeling process. If bone reabsorption occurs without an equal amount of bone formation, an overall loss of bone occurs.
When bone formation is unable to keep pace with bone reabsorption, the net result again is an overall loss of bone. Either of these abnormalities results in osteoporosis. Studies from the Mayo Clinic found that women lose 47 percent of their bone density from the spine, and 39 percent of bone is lost from the wrist during their lifetime.1 Spinal bone loss occurs at a rate of about 1 percent per year. At menopause, when estrogen production is reduced, the rate of bone loss increases to 3 percent or more per year. More recent studies suggest that women may begin to lose bone earlier than previously suspected, and that spinal bone loss may begin in the 40s.
Exercise for Optimal Bone Health
The overall role of exercise as an integral part of osteoporosis prevention and treatment is gaining popularity. Well accepted are the theories that disuse results in bone mass loss, that sedentary individuals in general have less bone mass development and may produce a modest increase in bone mass in years after peak bone mass and that exercise cannot compensate for estrogen loss.2 Upon review of over 100 research articles, the literature strongly suggests a positive relationship between exercise and osteoporosis, particularly from a prevention perspective. A comprehensive team approach using diet, estrogen, and exercise should be considered in attaining optimal bone health.
How Exercise Affects Bone
Bone tissue forms in response to many factors including heredity, nutrition, disease, and hormonal and biomechanical influences. The most prevalent theory on bone growth is known as Wolff’s law of bone transformation. It states that mechanical forces acting on bone could cause architectural changes in bone. This means that bone responds to mechanical stress and makes continual changes based on the conditions. Stress that is placed on bone can be positive or negative.
Exercise, which can induce bone hypertrophy, is an example of positive stress. It appears that the magnitude of force and frequency of its application affects the stimulation of osteoblastic activity, the process responsible for bone formation.
An Exercise Prescription for Optimal Bone Health
The amount of exercise training necessary to create an adaptive response for optimal bone tissue is for the most part undecided and is highly individual. Until we know at what threshold level bone does respond, the exercise recommendations for intensity, frequency and duration should be based on present knowledge and adhere to the American College of Sports Medicine (ACSM)
Program design to optimize bone health should include the following:
- Weight-bearing exercise such as walking, jogging, dancing, racquet sports, or stair climbing (on real stairs)
- Resistive training
- Exercises that place mechanical stress on the spine, femur and wrist
- Balance and agility activities for fall prevention
- Exercises performed with correct posture alignment
- Posture and spine stabilization exercises
In addition, the following strengthening exercises are valuable for the spine, wrist and forearm, and the femur.
Strengthening exercises for the spine:
- Pullover Dumbbell bent over lateral raise Shoulder shrug Bent over low Upright row Seated row
- Lateral raise
- Lat pulldown
- Back extension
- Neck and spine extension
Strengthening exercises for the wrist and forearm:
- Weighted wrist roll
- Wrist flexion (curl)
- Wrist extension
- Wrist lateral flexion
Strengthening exercises for the femur.
- Squat Leg press
- Hip adductor/abductor machine
- Leg extension
- Leg curl
Osteoporosis Exercise Program Goals for Prevention
The following are goals for osteoporosis prevention:
- Maintain bone mass
- Prevent bone loss due to aging
- Maintain joint mobility
- Improve coordination
- Improve posture
- Increase muscle strength and endurance
- Maintain correct postural alignment
- Attain cardiorespiratory fitness
- Reduce risk of falling
Exercise may also have positive benefits in the treatment of osteoporosis. Howevef, certain contraindications are involved while training clients with diagnosed osteoporosis:
- Omit exercises that flex the spine (bending forward at the waist) for clients with diagnosed osteoporosis in the spine. Sinaki3 found that trunk flexion exercises increased the rate of spinal fracture by 89 percent, compared with a 16 percent fracture rate in the back extension group. This means omit crunches, abdominal curls, and rowing machines.
- Avoid bringing the knee to the chest, as this may compromise the spine.
- Avoid activities or movements that place clients at risk for falling. This includes exercising on slick floors, step aerobics, quick directional changes.
- Avoid high impact, jarring, jumping, or jogging activities. This can increase the risk of spinal fracture, as weakened vertebrae cannot tolerate this force.
- Avoid pulling the neck forward if hands are placed behind the head.
Some women have been advised not to exercise after an osteoporotic fracture. However, no exercise only perpetuates the osteoporosis and will result in an overall decline in health. The primary objective is to exercise safely.
1.Sydney, L. The Osteoporosis Handbook -Every Woman’s Guide to Prevention and Treatment. Taylor Publishing.1997
2.C.H. Chesnut, Bone mass and exercise, Am J Med (1993) (Suppl 5A), pp. 34s–36s.
3. Sinaki, M. 1988. Osteoporosis: Etiology, Diagnosis. Raven Press, New York. 457-465.
National Institutes on Aging PO Box 8057 Gaithersburg, MD 20898 800-222-2225
National Institute of Health 9000 Rockville Pike Bethesda, MD 20892 301-496-4000
National Osteoporosis Foundation 1150 17th St NW Ste 500 Washington, DC 20036 202-223-2226
Gwen Hyatt, MS, founded DSWFitness (Desert Southwest Fitness, Inc.) in 1980 to provide continuing education for fitness, health, rehabilitation and clinical professionals. She holds a double master’s degree in exercise science and gerontology, and has authored 14 correspondence courses and presented at more than 20 IDEA conventions. She has written over 15 courses for health and fitness professionals including a comprehensive course on exercise and osteoporosis.