Question: I've read a lot about aerobic exercise, particularly about breaking sessions into 10- to 15-minute "mini-bouts" a few times a day. What about warm up and cool down times? Does one need warm up and cool down with these shorter workout periods?

Answer: Warmups and cooldowns are important to increase circulation and warm your muscles if you are going to be performing intense exercise, such as jogging or strength training. Short bouts of exercise are designed to be more moderate "lifestyle" types of activity, such as walking around the block, going up and down a flight of stairs, or performing simple calisthenics. In other words, a short bout of exercise does not mean getting out of your car and sprinting down the block for 2 minutes before work. For that, you would need a warm-up.

Even though short bouts are not inherently intense, they can be just as good for you as more vigorous exercise, according to research. In a 2-year study of more than 230 overweight, sedentary folks, researchers from the Cooper Institute for Aerobics Research in Dallas found that men and women who upped their physical activity by taking the stairs at the office, walking around the soccer field during their kids' practice, and gardening had about the same improvements in fitness, blood pressure, and body fat as did people who went to a gym for 20 to 60 minutes of vigorous exercise, 5 days a week.

In a similar study at Johns Hopkins University, researchers found that people who added just 30 minutes of lifestyle activity to their day lost almost 10 pounds during the 16-week treatment period--more than a comparable group who did step aerobics 3 days a week.

If you are not sure how to sneak more short bouts of exercise into your day, try the following schedule. It will increase your daily exercise time by 30 minutes while barely changing your daily routine.

Mid-Morning Break
Grab a coworker (or another mom if you're at home) and catch up with each other. Walk 10 minutes around the building or block at a casual, lively pace.

Mid-Afternoon Slump Buster
Pick up a pad and pencil. Walk down the hall or around the house for 5 minutes, marking off what you need to do for the rest of the day.

Six o'clock Stretch
After dinner (and before second helpings), get up and take a 10-minute walk through the neighborhood. Walk just above a strolling pace, as if you had somewhere to be.

Commercial Break
Get up during the commercial interruptions in your favorite show and do 1 minute of stairs, jumping jacks, or marching in place for a total of 5 minutes throughout the show.

Though true strength training with weights is best, you can also sneak in simple toning moves throughout the day. Here are two moves--one for the lower body and one for the upper body--that you can do (while no one's watching) in your office or even while cooking dinner.

Plié & Relevé
Stand with your legs wider than shoulder-width apart, toes pointing out to the sides as far as comfortably possible. Hold your arms out to the sides and slightly forward for balance (place one hand on a chair for support, if needed). Keeping your heels firmly planted, slowly bend your knees, dipping your butt until your thighs are nearly parallel to the floor. Pause, then slowly straighten your legs and immediately rise up on the balls of your feet. Pause, then lower your heels back to start.

Dips
Sit on the edge of a chair with your hands grasping the chair seat on either side of your butt. Your legs should be bent about 90 degrees with your feet flat on the floor. Slide your butt off the chair seat and walk your feet forward slightly, maintaining the 90-degree angle with your legs. Keeping your shoulders down, slowly bend your elbows straight back, lowering your hips toward the floor until your upper arms are nearly parallel to the floor. Pause, then return to the starting position.