Interval training keeps workouts moving

Whether you're a professional athlete or just trying to shape up for summer, interval training can help. Its bursts of intense exercise followed by easier, slower activity can help you burn calories and build strength.

What is interval training?

Cardio interval training is alternating cycles of fast and slow, intense and lighter exercise.

You can try it on the treadmill, stair climber or stationary bike. It also can be used on strength-building machines or while lifting dumbbells, doing squats or even swimming. You don't need expensive equipment: Interval training is perfect for push-ups, dancing and jogging or walking outdoors.

The intervals include intensity changes in speed, the number of repetitions of a task or the weight of a lifting load.

"It's not the equipment that's important, it's how you apply it," said William J. Smith, director of fitness education for the Can Do Fitness Clubs in Wayne, N.J.

At a Lodi, N.J., gym recently, 56-year-old Steve Browne spent a 20-minute treadmill session alternating between one minute at a fast pace and two minutes at a slower pace. His speeds varied between three and five mph, the inclines changing from two to eight degrees.

"I usually go by how they feel, to know whether to push them more or hold back," said Nicole Marino, his personal trainer and owner of Absolute Fitness in Lodi.

Browne wound down with five minutes of walking at 2.5 mph on a zero-degree level."If you just stop, it's not healthy," Marino said. "You have to let your body cool down. That's even if you're advanced."

What will interval training do for me?

Proponents of interval training say these bursts of intense and lighter exercise can jumpstart your fitness by:

1. Burning far more calories - and more fat - than in low-intensity workouts.2. Building your endurance faster than slower-paced exercises.3. Stimulating your metabolism - you can continue to burn calories and fat long after you're done working out.

"Intervals activate heart rate and facilitate blood flow," Smith said. "Intervals increase endorphins," the brain chemicals believed to reduce pain and enhance pleasure.

It's also a good workout to try if you're squeezed for time: You can work yourself as hard in just 30 minutes of interval training as you can in an hour of low-intensity exercise.

Fitness is an uphill battle at this stage for many baby boomers or anyone who sits for hours in front of a computer. They need the intensity of interval training to reap long-term benefits that moderate exercise doesn't always provide, Smith said.

"You've got to push your body," he said. "It's about getting fitter and living better."What should I be concerned about?

Before starting interval training, assess your fitness level and talk to your doctor about any health conditions that might be affected by exercise.

Interval training is wonderful exercise, but people who are out of shape shouldn't jump into it, said Dr. Samuel Suede, a cardiologist at Englewood Hospital and Medical Center.

"I'd encourage it, but a sedentary person needs to start slowly," said Suede, assistant co-director of cardiology at Englewood.

"A sedentary person has to be very smart about it," he said. "Start off with short, not very intense exercise. Alternate walking with simple jogging. Then build up to jogging alternating with running."

Whether a person wants to strengthen the body or burn fat, "the No. 1 aim for intervals is completing the task without injuries," Smith said.