Women are at several disadvantages when it comes to optimal muscle health. With age, our muscles deteri­orate at a faster rate than men’s, explains Michael Bemben, an exercise physiologist and professor in the department of health and exercise science at the University of Oklahoma. The neurons that control muscles in both genders are programmed to die off with age. “Men typically have more muscle to begin with so they can afford to lose some, whereas women can’t,” he adds.

It’s also more difficult for women to replace lost muscle than it is for men. A study in the journal PLoS One found older women have less effective muscle protein synthesis—the process that breaks down food to build muscle—than men. So the researchers advise us to eat enough protein.

We also need power, endurance and strength. Older women saw only a 10 percent increase in muscle power versus a 50 percent rise for younger women doing comparable exercises, according to a study in Medicine & Science in Sports & Exercise. Power is more closely related to the ability to perform daily activities and reduce the risk of falls than muscle strength alone, states Dain LaRoche, the study’s co-author and assistant professor of exercise science in the department of kinesiology at the University of New Hampshire.

The good news? With exercise, older women can build up muscle strength. But to achieve “net muscle gain,” we need to work on improving our muscle health now, says Jennifer Jakobi, an assistant professor in the school of human kinetics at the University of British Columbia. “It’s like retirement savings: The more you invest in your muscles, the larger the base you have to function longer.”

Here are the four key target zones you should exercise now, so that as you age you can golf and garden without pain—and travel the world without a walker.