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Family Health Magazine - ACTIVE LIVING

Who is at risk for osteoporosis?
Exercise builds your bones

Remember the seventies' TV cartoon characters Fred Flintstone and George Jetson? The Flintstones came from the prehistoric era, while the Jetsons lived in an automated world of the future. Who would have stronger bones, Fred or George?

Well, Fred's got a good hundred pounds on George and a large proportion of his weight is muscle mass. Remember, Fred worked in the rock quarry lifting and hauling stone every day. The Flintstone family car was propelled through the courtesy of Fred's two feet, kind of like 'power walking' in a box. George Jetson, meanwhile, pressed a button and floated around in his hover car. Even walking was automated for George, thanks to moving sidewalks very similar to these in many airports today.

Fred versus George

It is fair to say that Fred, the prehistoric guy, was more physically active. Since he did daily weight-bearing activity, he was more likely than George to have stronger muscles and bones! With all his futuristic conveniences, including the luxury of defying gravity, George is more at risk of osteoporosis.

What is osteoporosis?

Osteoporosis is a medical condition in which bone density decreases. Bones become porous and more compressible, like a sponge, rather than dense like a brick. Over time, they become weak and brittle. Brittle bones break more easily, which can lead to other health concerns. Osteoporosis is a major health problem in Canada. Around 1.4 million Canadians are thought to suffer from osteoporosis. The good news is that proper medical management, nutrition counselling, and a well-designed exercise program can reduce the risk of developing osteoporosis or lessen its effects.

How does bone density change with age?

By age 18, skeletal growth is nearly complete. Once peak bone mass is achieved, bone density slowly decreases. The rate of bone density loss increases, especially for women following menopause. The denser your bones are when young, the more density you retain as you age. Regular exercise is especially important for children and teenagers while they are developing healthy bones. High-impact and weight-bearing activities appear to be most helpful to the skeleton. Kids who dance, run, jump, and play soccer, volleyball, and field hockey are making the most of their ability to build bone density at a young age.

What does exercise do to the bone?

Regular exercise affects bone density, size and shape. The mechanical strength of the bone improves greatly. Exercise can decrease the rate of bone loss and reduce the risk of fractures. Not only does exercise improve bone health, but it also increases muscle strength, co-ordination, and balance, leading to better overall health. Since George Jetson was a bit of a klutz, he might have benefited in more than one way from a well-designed exercise program.

What types of physical activity increase bone density?

Weight-bearing and resistance exercises are the best physical activities for bones, as they force the body to work against gravity.

What are weight-bearing exercises?

Weight-bearing exercises transmit the weight of the body through the bones. Bones respond to this force by growing stronger. Power walking, hiking, jogging and stair-climbing are all examples of individual weight-bearing exercise. Exercises such as swimming or bicycling do not build bone in the same way.

What about walking?

Walking is an excellent weight-bearing exercise. Several research studies have shown that women who walk briskly gain bone density. Walking at an intensity that elevates your heart rate does your body the most good.

How often should weight-bearing activities be done?

Weight-bearing exercises should be done at least three to five times per week. The goal is to work up to 45 minutes or more per session. Someone who already has osteoporosis should not do high impact activities such as jogging or high-impact aerobics. These exercises can jar the spine too much, increasing the risk of fractures of the vertebra.

What are resistance exercises?

Resistance exercises generate muscle tension on the bones. Muscles are strengthened and bones stimulated to grow stronger. Exercising with weights or resistance bands are examples of this type of exercise. By lifting and hauling rocks, Fred increased his muscle mass. Resistance exercises should be done two to three times a week.

Are exercises site-specific to building bone?

Exercise has been shown to be site-specific. In fact, the more a bone or joint is used, the greater the bone density. Racquet sports such as tennis provide the perfect example. In tennis players, the arm that holds the racquet has greater bone density than in the other arm, mainly used to toss the ball up in the air. An exercise program should be designed to load the target areas most at risk for fractures. Fred's work at the quarry loaded several bones and helped maintain his overall bone density. Fred was at less risk for osteoporosis since his daily activities targeted areas most affected by the disease - the spine, hips, and wrists. It is important that exercise programs be weight-bearing and site-specific to these parts of the back, legs, and lower arms.

How much resistance is enough?

Bone responds to the mechanical forces placed upon it. Placing more weight on bones than the body is accustomed to will increase bone density. Weight-bearing and resistance exercises can stimulate bone density as long as there is enough weight. Gradually increase levels of resistance in order to keep building bone density.

How many repetitions should be done?

Bone density increases with low-repetition, high-weight programs. Studies have shown that bone density after menopause can significantly increase by using a low-repetition, high-weight program. This effect is not seen with a high-repetition, low-weight program.

Those who have or are at risk of osteoporosis should do at least one set of eight to ten repetitions of an exercise. At best, try to do three sets with a one- to two-minute rest between sets. Once ten repetitions can be done easily, increase the weight gradually to continue building bone density. This is called a progressive resistance training program, or PRT.

Can older people do a PRT program?

It is never too late to start exercising. Fortunately, it is not too late for George Jetson, as long as he is willing to do a PRT. Several studies suggest that a PRT can help reduce the risk or degree of osteoporosis while improving overall fitness and quality of life. In fact, this type of program is generally accepted as the best way to maintain and improve function in older adults.By now, George Jetson must be old, possibly living in a retirement home. A PRT program would still be recommended for him. Many intervention studies done with elders living in the community and in institutions support this type of program.

What other exercises are important?

Strengthening back muscles can help counteract the rounded posture often seen in osteoporosis. It can also reduce the chance of spinal fractures. Women with stronger back muscles have been shown to have a significant increase in bone mineral density of the spine. Many exercise programs fail to include the spinal extension (backward-bending) exercises necessary to any osteoporosis program.

What exercises should be avoided?

People with osteoporosis should avoid any exercises that increase forward bending or rounding of the spine. These exercises include sit-ups, toe touches, and the use of exercise equipment that causes the spine to bend forward (such as some abdominal exercise machines). Forward bending exercises have been found to increase the chance of spinal fractures in women with osteoporosis.

When does a person stop exercising?

Exercise should continue throughout your lifetime. Bone mineral density gains from exercise are only maintained as long as the exercise is continued at the same level of intensity. George Jetson falls into this category of do it or lose it! Since George didn't really do any weight-bearing physical activity, he is a prime candidate for osteoporosis.

Wouldn't Fred Flintstone be proud to know that the future of strong bones lies in the prehistoric way of life? Of course, George will be horrified when he finds out that he must give up the comfort of his hover car for good old-fashioned walking, uphill, with one pound weights in his hands!

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While effort is made to reflect accepted medical knowledge and practice, articles in Family Health Online should not be relied upon for the treatment or management of any specified medical problem or concern and Family Health accepts no liability for reliance on the articles. For proper diagnosis and care, you should always consult your family physician promptly. © Copyright 2010, Family Health Magazine, a special publication of the Edmonton Journal, a division of Postmedia Network Inc., 10006 - 101 Street, Edmonton, AB T5J 0S1    [AL_FHc05]