Circuit vs. Interval Training
By: Pam Archer

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These popular forms of group fitness training are also the most misunderstood class formats. I have observed instructors who are completely clueless as to what these terms mean. I have even observed music companies who are clueless to the meaning, listing music as circuit training, when it really applies to interval or vice-versa.

Interval and circuit training methods have been an integral part of our group fitness programs for more than a decade. Both are effective and fun ways to train and to challenge our participants. However, there are many misconceptions, misinterpretations, and misrepresentations of both types of training.   For example, a true Circuit class is one in which the heart rate is elevated and maintained at steady state, generally around 60-75% of maximum heart
rate, whereas an Interval class elevates the heart rate to the anaerobic threshold, approximately 85% MHR, for short intervals lasting 1-3 minutes, sometimes slightly longer, followed by an active recovery period, maintaining the heart rate in the training zone of 60-75%.

A Circuit class can follow many formats:  

Circuits can be performed in unison, everyone doing the same thing at the same time. Some examples might be:

1. Low impact aerobics or Step for 4 minutes with a one minute time period using resistance. Lower body movement is generally required to maintain the heart rate. Performing lunges while doing biceps curls, would be an example.

2. All resistance training, changing muscle groups every minute.

Circuit stations can be set up around the room.  Individuals move from station to station at the cue from the instructor. The stations can alternate between cardio, of moderate intensity, and resistance training. They can also be all cardio stations or all resistance training stations. Stations including slide, step, bicycles, power boards, trampolines, low impact aerobics, 2 laps of power walking, on the track, etc. are some stations I have used. Activities such as sweeping a ball around a room, dribbling a basketball around cones, sitting in a chair with rollers on it, in which you push off with your feet, but have to walk yourself back to start with your heels. Wow to the hamstrings! I have even had participants lie prone, on mats, and pull themselves across the room or sit on the mats and push along the floor with their feet. It's fun, child's play and definitely not boring! Use your imagination!

An Interval class can also have many formats:

1. It is mostly done in unison, in a group exercise situation, but you can do stations as well. You can perform high/low impact aerobics, using peak movements such as jumping jacks, squats, scissor jacks, etc., pushing to the anaerobic threshold for a short period of time, followed by less intense movement, staying within the heart rate training zone.

2. Active recovery can be done on the step and the anaerobic interval on the floor, or vice-versa.

3. An interval class can be done drill style. These intense movements need to be shorter in length than high/low aerobics. For example, one might do an intense punch/kick combination and lower intensity moves, such as a boxer's shuffle, for 
recovery.

Basic Guidelines:

Warm Up - Warm up should be specific to the class that you are teaching. The more intense and advanced the class is, the longer the preparation time. AFAA's guidelines are 8-12 minutes for all classes. Include stretches appropriate for the 
population that you are teaching.

Warm up should gradually elevate the heart rate.  You should be at the low end of target heart rate at the end of warm up. The transition to the cardio segment should be smooth and un-interrupted. I have seen way too much running to the stereo to change tapes while the participants stand and wait. You have just undone what you tried to accomplish in the warm up!

Exercise Selection:

Select exercises and sequences that are appropriate for the population that you are teaching. Our facility has an overall, older population. It would be inappropriate to include lots of jumping jacks, and other high-impact movements without offering modifications. Lots of modifications should be offered, regardless of the age of the class!

Avoid sudden changes in body position:

Dropping for push-ups out of a very intense, cardio movement can be very dangerous. Dizziness, fainting, heart arrhythmias and other dangers can occur when dropping the head below the heart while the heart rate is elevated. 

It is dangerous and inappropriate to elevate the heart rate to the anaerobic threshold and then suddenly drop it out of training zone by doing a stability ball exercise or any, similar, less intense movement. To do this type of yo-yo stunt to the heart, can result in heart attack, dizziness or other heart irregularities.

Evaluate every exercise you are planning to do for safety and effectiveness. Evaluate it for intensity as well. Make very sure that the intensity of the exercise is appropriate.

Music:

There are many professionally mixed music CD's available for circuit and interval workouts. They are complete with verbal cues or whistles to cue the change in stations. This eliminates the need for staring at a watch and it also keeps the music beats steady and within a proper range for training.  Homemade tapes can be okay if you know what you are doing, but I know very few instructors who can pull this off effectively.

Both Circuit and Interval Training can give a jump start to the metabolism. I often prescribe interval workouts to clients who have reached a plateau in their training. 

Whichever format or class structure that you choose, keep in mind your purpose for the class, the population of the class, and the guidelines for teaching a great, yet safe, class. Always remember that the workout is for THEM!

Pam is the owner of Archer Fitness Consultants, Inc. in Kingsport, Tennessee. She is Co-Host of the “Jenny’s Fit In 15” TV show on The Health Network. She has produced six exercise videos and starred in seven. Pam travels extensively training and certifying group fitness instructors for The Aerobic and Fitness Association of America (AFAA) and The American Council On Exercise (ACE). Her fitness related articles have been published in American Fitness and IDEA Source magazines as well as numerous newsletters, including her own, Archer Fit Press. You may visit Pam on-line at http://www.archerfitness.com or e-mail her at pam@archerfitness.com

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