Exercise's Effects on Bones and Muscles
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| Joints, particularly hinge joints like the elbow and the knee, are complex structures made up of bone, muscles, synovium and cartilage and ligaments, designed to bear weight and move the body through space. The knee consists of the femur (thigh bone) above, and the tibia (shin bone) and fibula below. The patella, or kneecap rides on top of the lower portion of the femur and the top portion of the tibia. The muscles and ligaments connect these bones and the space between them is cushioned by fluid-filled capsules (synovia) and cartilage. When muscles are exercised, they pull on the bones, strengthening them. The range of motion of a joint represents how far it can be flexed (bent) and extended (stretched). |
Exercise is critical for strong muscles and bones. Muscle strength declines as people age, but studies report that when people exercise they are stronger and leaner than others in their age group. There has been some concern that older people who regularly run experience more disability and joint and muscle injuries as they get older. A 2003 study, however, reported that running was associated with a longer life and less disability than not running.
Effects on Osteoarthritis
Joints require motion to stay healthy. Long periods of inactivity cause the arthritic joint to stiffen and the adjoining tissue to atrophy. A moderate exercise program that includes low-impact aerobics and power and strength training has benefits for osteoarthritic patients, even if exercise does not slow down the disease progression. Many patients who embark on an exercise program report less disability and pain and are better able to perform daily chores and remain independent than their inactive peers. Older patients and those with medical problems should always check with their physician before embarking on an exercise program.
The following are useful exercises for osteoarthritis patients:
- Strengthening exercises builds muscle strength. Some experts encourage patients to emphasize strengthening leg muscles as a first treatment step, even before using pain relievers. They fear that patients who rely on pain killing drugs may overuse knees, which do not have muscle tissue sufficiently strong enough to protect the joints from further damage. Strengthening the thigh muscles is certainly protective who have not developed osteoarthritis.
- Range-of-motion exercises increase the amount of movement in a joint and muscle. The best examples are yoga and tai chi, which focus on flexibility, balance, and proper breathing. In one 2001 study, older adults who practiced the gentle movement, breathing, and meditation exercises of tai chi for 10 weeks reported less pain than their peers who did not learn the technique.
- Low-impact aerobic workouts help stabilize and support the joint. Cycling and walking are beneficial, and swimming or exercising in water is highly recommended for people with arthritis. (Arthritic patients should avoid high-impact sports, such as jogging, tennis, and racquetball.)
- Some researchers are now focusing on "power" training, which involves improving the muscle's ability to move more rapidly against resisting forces, such as gravity. (For example, such training helps people to stand up or climb stairs more quickly.) Muscle power declines more rapidly than muscle strength and may be particularly important in older people.
Effects on Fracture in the Elderly from Osteoporosis (Loss of Bone Density) and Falling
Exercise is very important for slowing the progression of bone loss (osteoporosis) and extremely important for reducing the risk for falling, which causes fractures. Older women are at highest risk for this disease but older men are also at risk. Children should begin exercising before adolescence, since bone mass increases during puberty and reaches its peak between ages 20 and 30. In fact, studies report that exercise along with calcium supplements may help increase bone mass in teenagers. In one study, exercise even more effective than high calcium intake.
Specific exercises may be especially helpful for reducing the risk for fracture:
- Weight-bearing exercise are very beneficial for bones in people of all ages, even older people. This approach applies tension to muscle and bone, and the body responds to this stress by increasing bone density, in young adults by as much as 2% to 8% a year. Careful weight training can also be very beneficial for elderly people, particularly women. In addition to improving bone density, weight-bearing exercise reduces the risk for fractures by improving muscle strength and balance, thus helping to prevent falls.
- Regular brisk long walks improve bone density and mobility. In one 2002 study, for example, older women reduced their risk of hip fracture by over 40% by working out for just four hours a week.
- Exercises specifically targeted to strengthen the back can be beneficial in improving posture and may even reduce kyphosis (hunchback) in people with osteoporosis.
- Low-impact exercises that improve balance and strength, particularly yoga and tai chi, have been found to decrease the risk of falling. I n one study tai chi reduced the risk by almost half.
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Click the icon to see an image of the bone-building exercise. |
Note on Female Athlete Triad. Some young female athletes who exercise very intensely and are subject to intense pressure to remain thin are at risk for the so-called female athlete triad, which includes osteoporosis.
Effect of Exercise on Back Pain
Effects of Sedentary Life. People who do not exercise regularly face an increased risk for low back pain, especially during times when they suddenly embark on stressful unaccustomed activity, such as shoveling, digging, or moving heavy items. Although no definitive studies have been done to prove the relationship between lack of exercise and low back pain, sedentary living is probably a primary nonmedical culprit contributing to this condition. Lack of exercise leads to the following conditions that may threaten the back:
- Muscle inflexibility (can restrict the back's ability to move, rotate, and bend).
- Weak stomach muscles (can increase the strain on the back and can cause an abnormal tilt of the pelvis).
- Weak back muscles (may increase the load on the spine and the risk for disc compression).
- Obesity, associated with sedentary lifestyle (puts more weight on the spine and increases pressure on the vertebrae and discs). Studies report only a weak association between obesity and low back pain, however.
Benefits for Chronic Back Pain. People in with sudden and severe back pain should not exercise. Exercise plays a very beneficial role in chronic back pain, however. In one study, for example, patients with back pain lasting for an average of 18 months were assigned eight one-hour exercise sessions over four weeks. They showed greater improvement in nearly every area, including reduced pain and increased capacity, compared to patients who did not exercise. Exercise should be considered as part of a broader program to return to normal home, work, and social activities. In this way, the positive benefits of exercise not only affect strength and flexibility but they also alter and improve the patients' attitudes toward their disability and pain.
Repetition is the key to increasing flexibility, building endurance, and strengthening the specific muscles needed to support and neutralize the spine. Some exercise programs used for prevention or treatment of chronic low back pain include the following:
- Low-impact Aerobic Exercises. Low-impact aerobic exercises, such as swimming, bicycling, and walking, can strengthen muscles in the abdomen and back without over-straining the back. Programs that use strengthening exercises while swimming may be a particularly beneficial approach for many patients with back pain. In one study, for example, pregnant women who engaged in a water gymnastics program had less back pain and were able to continue working longer.
- Lumbar Extension Strength Training. Exercises called lumbar extension strength training are proving to be effective. Generally, these exercises attempt to strengthen the abdomen, improve lower back mobility, strength, and endurance, and enhance flexibility in the hip and hamstring muscles and tendons at the back of the thigh.
- Yoga, tai chi, chi kung. These exercises combine low-impact physical movements and meditation. They are based on principles of disciplining the mind to achieve a physical and mental balance and can be very helpful in preventing recurrences of low back pain. In one study, pilates, an exercise practice that uses yoga principles, was helpful in a woman with progressive and disabling severe low back pain from early scoliosis. This approach deserves further research.
- Flexibility Exercises. Whether flexibility exercises alone offer any significant benefit is uncertain. One study suggested that any benefits derived from flexibility exercises are lost unless the exercise regimens are sustained.
- Retraining Deep Muscles. Of interest are studies that are finding a link between low back pain and impaired motor control of deep muscles of the back and trunk. According to these studies, contraction exercises specifically designed to retrain these muscles may be effective for patients with both acute and chronic pain.
It is important for any person who has low back pain to have an exercise program guided by professionals who understand the limitations and special needs of back pain and who can address individual health conditions. One study indicated that patients who planned their own exercise did worse than those in physical therapy or physician-directed programs.
Hazardous Effects on the Back. On the other side of the coin, improper or excessive exercise is also an important risk factor for back pain.
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