Weight bearing physical activity is essential for bone health. Without it, there is a rapid and marked loss of bone. Exercise appears to help reduce the risk of osteoporosis by:
Maximizing bone mass in the young adult.
Maintaining bone mass in the mature adult.
Lessening bone loss in the postmenopausal woman.
When PM&R physicians recommend exercise programs for their patients' bone health and to prevent bone loss, they consider five general principles of physical conditioning:
Specificity: Exercise should stress the specific physiological system being "trained," in this case, the skeleton. The activities selected should stress those skeletal sites most at risk for osteoporotic fractures.
Overload: There must be a progressive increase in the intensity of the exercise in order to continually improve. PM&R physicians make sure the weight used can sustain the amount of stress.
Reversibility: The positive effect of exercise on bone will be lost if the exercise program is discontinued.
Initial Values: People with the lowest bone mass will have the greatest improvement; those with average or above average bone mass will have the least.
Diminishing Returns: There is a biological ceiling to the physiological improvements you can make. As this ceiling is approached, it takes more effort to make smaller gains.
Exercise for Special Populations
Individuals with suspected or known impairment of the skeletal system, known chronic neuromuscular impairment, nutritional and endocrine disorders, and those taking medication that affects bone density should consult their PM&R physicians about the exercise program they should use for rehabilitation purposes. This is particularly important for people with disabilities such as individuals with quadriplegia, paraplegia, and other forms of neuromuscular impairment.
Exercise as part of a rehabilitation program should be undertaken with the guidance of a physician and should be accompanied by other therapies. A rehabilitation exercise program must be tailored to the capacity of a person's skeleton to respond to exercise stress. For this reason, exercise for rehabilitation purposes should be under the direction of a physician knowledgeable in the pathophysiology and treatment of the patient's primary disorder and osteoporosis.
People over 40 who are starting an exercise program and those at risk for cardiovascular disease should also consult with their physician.
Exercise should be encouraged not just for the its cardiovascular benefits, but also because it maximizes bone mass in young adults and maintains bone mass in mature adults. Exercise programs designed to maintain muscular strength can slow the loss of bone mineral density. Both middle aged and elderly women increase bone mass or reduce the rate of bone tissue loss in response to exercise programs. The majority of bone production occurs by the age of 35.
At present, there is no evidence that physical activity alone can prevent bone loss and subsequent fractures. However, any increase in bone mass should be pursued. Other benefit of exercise—improved coordination, balance and muscle strength—may reduce fractures by simply decreasing the likelihood of falls.
Certain types of activities appear to be associated with higher than average bone mineral density. Activities associated with increased bone mass include:
Racquet sports (tennis, squash, racquet ball)
Field Sports (soccer, lacrosse, field hockey)
Court Sports (basketball, volleyball)
Dancing (folk, square, modern, ballet)
Swimming and walking have had both positive and negative results on increasing bone mass, so they are questionable as an exercise to pursue when trying to increase bone mass.
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