Interval training is an important part of aerobic exercise. If you're a walker or a runner, run intervals once a week. Walking and running build endurance by strengthening your cardiovascular system. Doing interval training once a week enhances your endurance by dramatically increasing the amount of blood your hear pumps every time it beats.¹ (This is known as your cardiac stroke volume.) Interval training also increases the amount of oxygen you can take in on each breath.² (This is known as your respiratory vital capacity.) The result is that you have noticeably increased speed and increased reserves when you need a prolonged burst of energy.

The same principles apply for any type of aerobic activity. . The interval system is easy to apply. For example, if you're a swimmer, you can do interval training with laps. If you ride a bike, you can do intervals with timed sprints.

There many books and magazine articles available to help you add interval training to your aerobics program. If you're doing aerobics exercise three times per week, you could use one of those sessions for interval training. Interval training is very powerful and the most important thing is to build up gradually.

To begin, you need to have a good base, meaning you do aerobic activity for at least 30 minutes. Using running as an example, you might be running 10-minute miles in at a fast "race pace". Ten minutes per mile is 2.5 minutes per quarter-mile. On your interval day, warm up by lightly jogging 1 mile. Then run four quarter-miles at a pace a bit faster than your race pace. In this example, you could run four quarter-miles at 2:25 or 2:20 per quarter. Then finish by lightly jogging for another mile.

Over time, your interval pace gets faster. You could do intervals with half-miles, three-quarters of a mile, or even a mile, if your weekly mileage supports such an interval distance. Most of us will see remarkable benefits by doing quarter-mile or occasional half-mile intervals.

One obvious result is that your resting pulse drops like a stone, because your heart is being trained to pump more blood each time it contracts. In this way, you save wear and tear on your heart. Owing to your heart's stroke volume, your heart beats less during the course of the day to provide the amount of blood you need flowing to your tissues.³ The takeaway is that your heart will last longer because you're doing intense vigorous exercise. That's a pretty remarkable result.

The bottom line is that interval training makes you stronger and faster. Your heart and lungs get a terrific workout with each interval training session. There's a big payoff for this once-a-week activity.

¹Molmen HE, et al: Aerobic interval training compensates age related decline in cardiac function. Scand Cardiovasc J 2012 Jan 24 (Epub ahead of print)

²Dunham C, Harms CA: Effects of high-intensity interval training on pulmonary function. Eur J Appl Physiol 2011 Dec 23 (Epub ahead of print)

³Hwang CL, et al: Effect of aerobic interval training on exercise capacity and metabolic risk factors in people with cardiometabolic disorders: a meta-analysis. J Cardiopulm Rehabil Prev 31(6):378-385, 2011