Beyond strength training
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 recommended last fall that most Americans 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, "this can be achieved by small changes in behavior, such as 15 minutes per day of walking."
When 8 Minutes Is Not Enough
Ken Turley, PhD, assistant professor of kinesiology and director of the Wellness Center at Harding University in Searcy, Ark., says the value of quick workouts depends on what you're aiming for