The Real Benefits of Strength Training

by Natalie Belford

Our bodies are programmed to hold on to body fat, especially in response to activity. During most of the time that humans have been on earth, they’ve had to endure ongoing stresses of heat, cold, hunger, and travel, and without the easy access to fat in their diets that we have today. Body fat for both sexes was a necessity for surviving a nomadic, rigorous existence. For women, body fat was even more important: it was what enabled us to conceive, bear, and nurse children without depleting our own resources to the point of death.

As a result, our bodies are constructed to sacrifice muscle long before they let go of fat—which is why any diet or weight loss plan must include some kind of muscle-building component to replace the tissue we’re losing.

Without exercise and physical activity, you’ll lose 20 to 50 percent of your muscle mass over the course of your adult life.

We all slow down a little bit as we age, but losing huge amounts of muscle mass means a major slowdown. So if you’ve been feeling unusually tired and overwhelmed lately, especially if you’ve been trying to diet, it may simply be that the accumulated loss of muscle tissue has finally caught up with you.

Studies by Wayne Westcott, Ph.D., research director at the South Shore YMCA in Quincy, Massachusetts, confirm the role of strength training in creating muscle and reducing fat. In one study, Westcott compared the muscle gain and fat loss of two groups of participants who exercised for eight weeks. One group did only endurance (cardio) exercise, while the other did endurance (cardio) plus strength training.

The endurance-only group had no change in muscle weight and only a 4-pound change in body composition (ratio of muscle to fat), while the endurance plus strength training group had a 2-pound gain in muscle weight and a 12-pound change in body composition.

If a loss of muscle mass is related to aging, the release of human growth hormone (HGH) is part of what keeps us youthful. Growth hormone is secreted by our pituitary glands in different amounts throughout our lives. As the name suggests, it’s most crucial during infancy, childhood, and adolescence, signaling our bodies to keep adding muscle, bone, and other tissue as we grow up.

Remember as a kid when your folks told you that protein rich foods—meat, fish, milk, and beans—would help you grow? Well, growth hormone is a crucial part of synthesizing that protein into muscle— as well as into thick hair, the collagen and elastin that gives you lovely skin tone, and the immune cells that protect you from disease.

Another key benefit of strength training is its role in building healthy bones and preventing osteoporosis. Most of us tend to forget that bones are made up of dynamic living tissue that is constantly being worn away and restored, just like the tissue in the muscles, cardiovascular system, and brain.

Osteoporosis results from a loss of bone mass—the failure of the body to restore the sturdy tissue that makes up our skeletal system.

Weight training creates and maintains bone strength in two ways. First, weight-bearing exercise, in which your bones are forced to bear either the weight of your body or the additional weight of a strength ball, free weight, or machine weight, encourages your system to strengthen and develop bone. Walking is a form of weight-bearing exercise, but strength training is even more effective.

Second, researchers have discovered that when muscles contract—as during strength training — the stress of the contraction is transmitted to the neighboring bone. This stress in turn creates an electrical charge within the bone, which stimulates the activity of the bone-building cells, or osteoblasts. This response in bone is what stimulates bone formation and prevents bone loss.