Q: I'm 79-years old and in good health. I've started a weight-training program at the local health club. How often should I do my exercises to keep the benefit going?

A: Before starting or increasing a weight-training program, it's advised that all adults over 65 have a physical exam and their doctor's approval. Hidden effects of atherosclerosis and coronary artery disease can lead to problems with this type of exercise.

Once you've been cleared, then try and work with an athletic trainer, physiotherapist, or exercise physiologist. A supervised program is always a good idea in the beginning. It's best to develop a regimen you can stick with over a long period of time.

Try to work all areas of the body including the arms, legs, calves, and abdominal and low back muscles. Most researchers advise training at least three times a week but not more than six. If you are using resistance-training equipment, then allow for a two-minute rest period between each machine.

Training the low back muscles once a week seems to be just as effective as doing it more often. Doing eight to 13 repetitions at 50 to 80 percent of your one-repetition maximum is best. Your trainer can help you find your one-rep max.

It takes six to eight weeks to change muscle fibers and build strength. You can continue increasing that strength by doing the exercises a full 20-weeks. The final goal should be to have a consistent exercise program that you can do week in and week out for years (the rest of your life!).

Kevin R. Vincent, MD, PhD, et al. Influence of Resistance Exercise on Lumbar Strength in Older, Overweight Adults. In Archives of Physical Medicine and Rehabilitation. March 2006. Vol. 87. No. 3. Pp. 383-389.