Fitness: Few Minutes a Day Increase Fitness Level (cont.)

The book specifies two different exercises for each day, working chest and back one day; shoulders and abdominals the next; then triceps and biceps; hamstrings and quadriceps; calves and butt; and inner and outer thighs.

"The program is very specific," Cruise tells WebMD. "It has been designed to provide short workouts -- preferably done in the morning -- that will give your metabolism a boost throughout the day."

The eight minutes a day of strength training should help you lose an average of two pounds a week, says Cruise, who also recommends an eating plan emphasizing portion control and "healthy" fats. But Cruise is quick to emphasize that his program is not designed for overall fitness. "This is exclusively for weight loss," he says. "If you want to work on anything else, this is not for you."

Within the fitness industry, Cruise is one of several proponents of short sessions of strength-training exercise. Similar philosophies can be found in the books Power of 10: The Once-a-Week Slow Motion Fitness Revolution by Adam Zickerman and Bill Schley, and Flip the Switch: Discover the Weight-Loss Solution and the Secret of Getting Started by Jim Karas, among others.

But while Cruise touts the health benefits of strength training -- it keeps your bones strong and your muscles toned -- he does not discount the value of other forms of exercise. "If you want to keep your heart and lungs healthy, then you need cardiovascular exercise," says Cruise, who includes a section on power walking in his book.

Indeed, the Institute of Medicine released a recommendation last fall calling for most Americans to get a minimum of 60 minutes of moderate-intensity exercise each day (other health and medical organizations recommend at least 30 minutes of daily activity). But there is scientific evidence for the benefits of short bursts of exercise -- at least when the exercise is the aerobic type.

For example, in a study published in the journal Medicine & Science in Sports & Exercise, researchers found that three brisk, 10-minute walks taken throughout the day can be at least as effective as one 30-minute walk at reducing cardiovascular risk and improving mood.

The study involved 21 sedentary men and women in their mid-40s. Five days a week for a six-week period, the volunteers either took 10-minute walks three times per day, or a brisk walk lasting 30 minutes once a day. Then, after a two-week rest period, the two groups swapped their walking routines and continued for another six weeks. Both groups saw a slight drop in total cholesterol levels and improved their levels of "good" cholesterol and their aerobic ability. Both the long and short walks brought decreases in tension and anxiety.

And James Hill, PhD, director of the Clinical Nutrition Research Unit at the University of Colorado Health Sciences Center, who recently analyzed two national surveys of U.S. eating habits, believes most people can avoid weight gain by simply cutting back 100 calories daily or by burning 100 extra calories a day. In the Feb. 7 issue of Science, Hill and his colleagues write that "this can be achieved by small changes in behavior, such as 15 minutes per day of walking."