Thousands of men and women have participated in the South Shore YMCA’s Keeping Fit research classes in the past 20 years. Now Rodale Publishers is releasing ‘‘Get Stronger, Feel Younger,’’ a book that draws its information and instruction on the studies conducted in Quincy.

This October, Rodale Publishers is releasing a book titled ‘‘Get Stronger, Feel Younger.’’ I am pleased to report that the information and instruction presented in this text is based on the research studies conducted at the South Shore YMCA in Quincy. Over the past 20 years, thousands of men and women have participated in our Keeping Fit research classes.
  
Unlike most diet or general exercise programs that emphasize weight loss, the Keeping Fit classes have always focused on body composition improvement.

To understand why this is important, let’s begin with the underlying cause of weight gain for most men and women, including those who eat reasonably and exercise regularly. First, unless you strength-train, you lose about 5 to 7 pounds of muscle tissue every decade of adult life. Aerobic activities, as good as they are for cardiovascular fitness, do little  to prevent the loss of muscle during the aging process.

Second, the muscle loss leads to a 3 to 5 percent per decade reduction in resting metabolic rate. Because your resting metabolism accounts for approximately about 70 percent of your daily calorie utilization, this seemingly small change in energy expenditure is largely responsible for an average fat gain of 15 to 20 pounds per decade. Keep in mind that a 20-pound per decade fat gain represents only 19 unused calories per day.

Third, low-calorie diets and general exercise programs are effective for temporary weight loss because of a negative energy balance (fewer calories eaten than needed). However, neither approach addresses the underlying problems of fat gain, namely, less muscle and lower metabolic rate. In fact, low-calorie diet plans result in further muscle loss and metabolic slowdown, thereby making weight regain almost inevitable.

Fourth, the only activity that reverses the age-related processes of muscle loss and metabolic slowdown is strength training. Based on our research, 10 weeks of basic resistance exercise builds, or replaces, 3 pounds of muscle, which increases resting metabolic rate by about 7 percent, and results in 3 pounds to 12 pounds of fat loss. Obviously, this is an excellent means for attaining and maintaining a healthy body composition and body  weight.

Let’s review the key differences between the two most popular weight-loss methods: low-calorie diets and general exercise versus the strength- training strategy. Low-calorie diets reduce fat, but they also result in muscle loss and metabolic slowdown. General exercise programs are beneficial for using energy and improving fitness, but most do not build muscle. Strength training, on the other hand, concurrently increases muscle tissue and metabolic rate, which facilitates fat loss, improves fitness and enhances appearance.

For example, a typical low-calorie diet plan may result in a 9-pound fat loss and 3-pound muscle loss. On the scale, this appears as a 12-pound weight loss, but it really represents 9 pounds in the right direction (fat loss)  and 3 pounds in the wrong direction (muscle loss), for an actual body  composition improvement of 6 pounds (half what the scale indicates).

Conversely, a typical strength- training program may result in a 9- pound fat loss and a 3-pound muscle gain. On the scale, this appears as a 6- pound weight loss, but it really represents 9 pounds in the right direction (fat loss) plus 3 pounds in the right direction (muscle gain), for an actual body composition improvement of 12 pounds (twice what the scale indicates).

The strength-training approach is clearly superior in the short term and even more advantageous over time. But how much time must you spend doing resistance exercise to achieve these beneficial outcomes? Much less than you may think.

Our research program participants do 20 minutes of strength training two or three days a week for 10 weeks.
  
Each training session consists of 10 resistance exercises performed for one set of about 10 repetitions. They take about 1 minute to complete each exercise set (6 seconds per repetition), and about 1 minute between successive exercises (during which they do a 20-second stretch for the muscles just worked). Our classes also include about 20 minutes of cardiovascular activity (treadmill or cycle) for heart health and additional calorie burning benefits.

The Patriot Ledger

Wayne L. Westcott, Ph.D., is fitness research director at the South Shore YMCA in Quincy, and author of 22 fitness books.