Quality of life is highly dependent on muscle strength, particularly in older adults. Muscle mass and strength correlate inversely with osteoporosis, glucose tolerance, lipid abnormalities, obesity, coronary heart disease and they correlate directly with functional status. In a young person, 90% of a cross-sectional area of the thigh is muscle mass. Only 30% of nursing-home residents' thighs are muscle. Even athletes core-muscle mass declines with age, so it probably isn't all a "disuse atrophy."
Endurance training is not the best form for retaining muscle strength. It has been shown that motor-neuron cells decrease with aging, the alpha-motor neurons. This may be due to age or negative feedback effects, again secondary to disuse.
Social and psychologic factors commonly seen in an older person lead to disuse. Also, numerous disease states, such as rheumatoid arthritis, lead to disuse atrophy. Protein and calorie malnutrition also will encourage disuse.
In an autopsy study, carried out in healthy accident victims over the age of 80, muscle fibers were seen to be affected-type II more than type I. The situation is compounded by the association between energy expenditure and muscle mass. The less you move, the less muscle mass you have, which prompts you to move less, and on and on. Central obesity is decreased by resistance training.
Exercise leads to a 1% to 5% increase in bone density per year. This is not quantitatively a great deal, but can have major functional importance. With this slow rate of change it is important that experimental situations last more than one year, lest the effect not be seen.
A person's walking ability correlates with muscle area. Training helps weak nursing-home residents to increase the speed of regular eight-meter walks.
In the strength-training progression, no "plateau" was noted, even after one year. Further, strength training increases aerobic fitness -- even though the reverse is not true. Thus it may be more cost-, time- and health-efficient to emphasize strength training over aerobic training.
Strength training also improves balance and increases spontaneous physical activity outside the training program. Stair-climbing and housework capabilities are improved with resistance training. The best "bang for the buck" is with strength training, as health improves.
Older persons should be trained at a high "work intensity." Don't baby them; avoid the ball-tossing. A ten-week strengthening program for older persons resulted in a 100% increase in strength.
Food supplements, with or without exercise, are without apparent benefit.
Exercise also is non-drug therapy.
How do you set up an effective program? Not in a lab environment.
There are four forms of exercise: muscle strengthening (resistance); aerobics; flexibility; and balance.
Resistance training is the only one with positive effects on the other three.
A Finnish study in 12 older weight-lifters observed that their 60-year-old muscles resembled those of a 20-year-old "control" with no weight training.
Isometrics are effective, cheap, and available -- all you need is a wall. But they are very specific to isolated movements, and there is no flexibility or balance benefit from isometrics.
The important issues in resistance training are pre-assessment, frequency, intensity, adherence and safety. It appears that 70% to 80% of a maximum repetition effort is the ideal training intensity. Increase in strength is evident after just two or three sessions. It is therefore important to increase the workload continually to sustain improvement benefits.
The first evidence of the strength-building progression was recorded in ancient Greece as a young man continually carried a calf. He became progressively stronger as the calf grew.
In performing an exercise, do it slowly -- and don't cheat: Don't let momentum do the work for you.
It appears that eight repetitions for two or three times are enough -- perhaps five minutes per muscle group.
Resistance training is extremely safe. In my work I have never had an adverse cardiac event. Actually, skeletal injury is less than with aerobic exercises. Pollack reports that 60% of a group of 50- to 70-year-olds had some skeletal injury during a walk/jog program.
Take a good health history before weight training. Muscle strengthening helps arthritis and helps prevent falls. Quality of life, independence and preservation of function are the main goals for resistance-exercise programs.
Various strategies must be employed for hard-to-reach populations. Accessibility and economics are major issues.
A study in 18 community nursing homes shows a decline in function and death rates as the end-points. A strengthening program helps improve the image of a nursing home from merely "being a warehouse" to a place for functional improvement. The work is done mostly by nursing assistants -- who are some of the most important caregivers in nursing homes.
Where such programs are properly implemented, half the residents become involved. The strength-training protocol is now extended to home-care as well.
The protocol involves 11 different sitting and standing exercises -- with slide illustrations available. So far there is an 85% compliance -- a compliance call is made weekly and a compliance log is maintained. Improved function is noted.
It is never too late to start, as evidenced by a 79-year-old muscle builder. Although it may be optimal to start early, our group includes a woman who started at age 96 and is still exercising actively seven years later -- at age 103!
Maria Fiatarone, Ph.D., Associate Professor of Medicine, Harvard University School of Medicine, spoke on "The Development of Strength and Muscle Mass in Older Adults."
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