Fitness benefits of sprints equal longer workouts

By Anne Harding

NEW YORK (Reuters Health) - Short, very intense bursts of exercise may be just as good as longer workouts for helping people get fit, a new study shows.

Young men who put in 10.5 hours on an exercise bike over two weeks were no more fit than those who exercised intensively for 2.5 hours during the same period of time, Dr. Martin J. Gibala of McMaster University in Hamilton, Ontario and colleagues found.

"To our knowledge this is the first study to demonstrate that sprint-interval training is indeed a very 'time efficient' training strategy," Gibala and his team write in the Journal of Physiology.

The catch is that this time saving required some serious energy expenditure. Participants in the sprint-interval training group pedaled "all out" for 30 seconds straight, four to six times, with a four-minute rest period between each session, while the endurance group kept up a steady pace for 90 to 120 minutes per session.

In an interview with Reuters Health, Gibala said that while he would never recommend this kind of workout for a heart patient, interval training can be tailored to people at just about any fitness level.

With the caveat that anyone starting an exercise program should consult his or her doctor, Gibala suggested that, for example, someone could walk a bit faster than usual for one minute, than back off for one minute, and repeat the cycle 10 times.

While a longer workout would clearly burn more calories than a shorter one, he added, these shorter workouts are much easier to fit into a busy schedule, and can also help "spice up" a person's exercise routine.

"People get bored walking on a treadmill for an hour, running around the block for an hour," he noted. The best approach, he added, would probably be to perform one or two interval sessions a week, along with endurance and resistance training.

In the current study, Gibala and his team randomized 16 young, fit men to six sessions of interval training or six endurance sessions over a two-week period. The interval sessions lasted a total of 18 to 27 minutes.

Both groups showed identical increases in fitness as measured by timed trials on exercise bikes after the two-week training period, and similar increases in their muscles' ability to use oxygen.

"We know the number-one cited barrier to exercise is lack of time," Gibala noted. "You have 20 minutes, you can still get some benefits using an interval-based approach."

SOURCE: Journal of Physiology, September 2006.