The following are excerpts of an article by Dr. Wescott, published in Fitness Management magazine. Wayne L. Wescott, Ph.D. is the author of the college textbook Strength Fitness: Physiological Principles and Training Techniques.
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Seniors on the Go!

During the past two years there has been a lot of interest in the aging process and strategies for delaying degenerative problems. Although we all grow older, physical inactivity appears to accelerate the adverse effects of aging. Consider the physiological responses to sedentary lifestyles.

It is an unfortunate fact that about 90% of all Americans do too little exercise to receive any fitness benefits. Most of those who do perform regular exercising engage in aerobic activities such as walking , jogging, cycling and dancing. Although these activities are beneficial to our cardiovascular system, they do little to prevent deterioration of our musculoskeletal system. Unless we perform regular strength building exercise, we lose approximately 5 to 7 lbs. of lean tissue, mostly muscle, every decade. Because our muscles are the engines of our bodies, this loss has a major impact on our physical ability and functional capacity. In essence, we go from an eight-cylinder engine to a six-cylinder it engine to a four-cylinder engine.

Because engine size is closely related to fuel utilization, it is easy to understand why less muscle leads to a lower metabolic rate. In fact, our muscle loss is largely responsible for the 2 - 5% per decade reduction in our resting metabolism.

An obvious outcome of less muscle and lower metabolism is gradual weight gain, averaging about 10 additional pounds per decade. Quite simply, calories that were previously used for muscle tissue maintenance are put into fat storage resulting in creeping obesity.

The average aging adult addresses weight gain by periodically dieting. According to Tufts University, 40% of American adults are presently following a low-calorie diet. Unfortunately, dieting without exercise is largely counterproductive. First, about 25% of the weight loss from low-calorie diets is muscle tissue. This further reduces resting metabolism. Second, about 95% of all dieters regain the weight they lose within one year. Because the regained weight is mostly fat, their body composition becomes worse after each diet.

Most adults misunderstand the cause and solution to the weight gain problem. They do not realize that the loss of muscle leads to the addition of fat. They are even less aware that the loss of muscle is related to osteoporosis and a variety of degenerative diseases.

Fortunately, it is possible to replace much of the muscle that has been lost to sedentary lifestyle.

Physiological responses to strength exercise.

Several studies have demonstrated that seniors can increase their strength and muscle mass. Other benefits from regular strength training include better blood lipid levels, improved glucose metabolism, accelerated gastrointestinal transit, decreased back pain, and reduced arthritic discomfort.

Based on these studies, it appears that sensible strength exercise is an excellent means for improving numerous physiological factors and maintaining a high level of musculoskeletal fitness throughout adulthood. For those who have been sedentary, it is possible to reverse many of the degenerative effects associated with the aging process.

Specifically, regular strength exercise can replace muscle tissue and increase metabolic rate, which is like changing from a low-power small car to a high-powered sports car.