"Traditionally, women have undervalued muscles," says Nelson, author of Strong Women Stay Slim (Bantam, 1998). But muscle is critical for long-term health and maintaining the body shape most women want. Here are the benefits you can expect from strength training.
20s and Early 30s
You're still young enough to build bone density at this age an investment of immeasurable value throughout your life. Plus, "muscle is your metabolic engine," Nelson says. Weight training increases your muscle mass, which increases your calorie-burning potential even while at rest. Strength training also reduces the chance of injury from the activities of daily life.
Late 30s and Menopause
"At this age it's common to begin losing an average of a third of a pound of muscle per year and gaining the equivalent amount in fat," Nelson says. Strength training offers a double defense: You burn calories during your workout, and the added strength boosts your walking speed, which burns more calories. Muscle is also key to maintaining an attractive, feminine shape.
"Women ask if they'll bulk up," Nelson says. "The answer is no; stronger is actually more feminine. Fat is loose, jiggly, and bulky, while muscle is trim, firm, and shapely."
On top of her clinical research, Nelson cites Marilyn Monroe's dedication to weightlifting as evidence that strength training builds a shapely body.
50s and Beyond
Resistance training can help maintain mobility and self-reliance with less chance of injury. "I have women in their 50s, 70s, even 90s, hiking, climbing mountains, playing sports. The key is that they've maintained their strength," Nelson says. "The great irony would be to have good cardiovascular fitness late in life, but then lack the strength to be able to enjoy it."
Weight training has therapeutic value, too. "People with bone or joint ailments like osteoporosis and arthritis may shy away, but they're the ones who will benefit most from maintaining strength and range of motion."