A Better Workout With Medicine Balls? I've been seeing more and more people working out with medicine balls at my gym. I'm trying to do more strength-training exercises to prevent osteoporosis. Do you think I should try working out with a medicine ball? Any suggestions on how to use it? Medicine balls do seem to be making a comeback. Roughly twice the size of a basketball, and weighing from two to 20 pounds, they were popular back in the 1930s and then disappeared until this recent resurgence. One reason they fell out of vogue was because the old-fashioned balls were filled with paper and cotton, making them moldy and smelly when they got wet. Today's medicine balls -- filled with gel, polyurethane, sand, sawdust, or rubber shavings -- don't get soggy when you get sweaty. The exercises you can do with a medicine ball are called "plyometrics," and there are more than a hundred of them, including a number of abdominal-strengthening moves, upper-body exercises, and just plain games of "catch" with a partner. The medicine ball owes its comeback to Donald A. Chu, Ph.D., a former professor of kinesiology (the study of movement), who is director of the physical-therapist assistant program at Ohlone College in Newark, CA. Dr. Chu's book, "Plyometric Exercises with the Medicine Ball" (Bittersweet, 1987), the bible of the medicine ball crowd, describes the exercises you can do. To protect against osteoporosis you should be doing both aerobic exercise and strength training. The aerobic exercise can be running, walking, aerobic dancing, or any form of cardiovascular workout that you do on your feet (swimming and biking are aerobic but don't have the bone-strengthening impact of exercises you do while standing). Strength training also offers protection against osteoporosis. Studies at Tufts University in Boston have shown that postmenopausal women who engage in strength training can actually gain, rather than lose, bone mass. Adding a medicine ball to your strength-training workout may make exercise more fun. I'm not aware of any scientific studies showing that use of a medicine ball gives you a more effective workout. There's no way to predict whether the return of medicine balls is a fad -- or whether they'll become permanent workout fixtures. If the exercises done with a ball appeal to you, I recommend scheduling a session or two with a personal trainer to learn how to use it effectively. Have fun!