Interval training is defined as a workout that changes the intensity of exercise at various intervals — typically with a difficult period followed by an easier recovery period. When applied to cardio workouts, interval training is a great way to add variety and crank up the calories burned. Plus, research shows interval training is the best way to improve your cardiorespiratory fitness.

Interval training is a great way to challenge your body in different ways because the varying intensity requires reliance on different muscles. This means you get a better overall body workout.

You can add intervals to any workout by alternating lower-intensity intervals, also known as recovery periods, with higher-intensity work intervals. The length and intensity of each bout can be tailored to meet your individual needs and training goals. An example would be 30 seconds to 2 minutes of higher-intensity intervals, alternating with 2 to 5 minutes of lower-intensity intervals.

If you are new to interval training, these tips will help you get started:

• The more intense the work interval, the longer you'll need to recover.
• The work intervals do not need to be at the same intensity. Likewise, the recovery periods can also alternate intensity and duration.
• There are various ways to crank up the intensity of the work interval. For instance, if you are jogging, you can either increase your speed or incline.
• Remember to start slowly and work from your current fitness level. If you are a walker, start by eyeing an object in the distance, such as a telephone pole. Then power walk to the object with good form. Return to your normal pace until your heart rate returns to your target range. Repeat this process throughout your walk.
• As your fitness level increases, adjust the difficulty of your session by either increasing the length or intensity of the work interval or decreasing the time of the rest interval.

Interval training can be as simple or as complicated as you wish to make it. Whether swimming, bicycling, rowing, dancing, or circuit training, intervals can enhance the quality and reduce the monotony of any exercise session.

Lori Rice, M.S., is a nutritional scientist and author with a passion for healthy cooking, exercise physiology, and food photography.