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Kick up the Cardio

Currently, health clubs offer a variety of cardio and strength options. They offer a plethora of equipment and classes yet attrition remains high. By combining the science of cardio and strength training with a motivated and energetic instructor new programming combining interval and steady-state routines will excite, motivate and retain your members.

What is circuit training?

The purpose of circuit training is to keep participants moving by only allowing minimal breaks between exercises. Rest is part of the circuit and it is based on the overall goal of the circuit. This workout is different from other programs or routines such as supersets or compound sets, which target one or two specific muscles and work with the fatigue factor of those particular muscles to increase the intensity of the workout. Circuit training, on the other hand, works because it creates an environment to keep pushing the body aerobically, while still challenging strength development.

Circuit training was popularized as a way to gain the benefits of both strength and cardio training. It involved doing a “circuit” in which one moved from weight machine to weight machine rapidly, doing high-rep sets with low weight and short rest intervals. This was supposed to keep heart rate up as well as strength train. Unfortunately, this did not really develop either capability. In fact, it proved a significantly poorer method of development on both counts. The prospective research shows unequivocally that training both strength and cardio simultaneously diminished the benefits of both. Further, the research is clear that doing cardio before strength maintains the cardio effect but enhances the strength training session.

In a classic Cooper Clinic study in 1982, which studied the effect of doing a circuit workout three times a week. The study had 77 participants (a rather small cohort), who were divided into three groups. One group did not train at all, one group did weights and a third group jogged in between weight sessions. Not surprisingly, the group that didn’t train saw no improvement in its cardiovascular fitness. The weights group improved cardio fitness by 12%. And the weights and-jogging group improved by 17%. Therefore, one could conclude that a circuit workout improves both strength and endurance and kick starts the metabolism. With circuit training members will leave the gym burning  1/3 more calories then they did in the workout and will continue to do so for several hours depending on the intensity of the circuit.

Now, this isn’t to say that circuit training is useless. There are effective ways to circuit train, just not in that fashion. For example, circuit training could be used as a fun way to circulate members between “technique stations” or various types of drills. This is evident in the industry with the development of the Kinesis program by Technogym. Stop by RallySport in Boulder, Colorado if you want to see the Kinesis program utilized optimally. It can mix up a workout in a challenging fashion. In this case, each activity is performed with adequate rest and the emphasis is on the skills developed from the variety of exercises. Other types of circuit training could be something like an obstacle course, where again the focus is not on development of maximal strength or muscle mass, but rather mastery of difficult, repeated activities.

Keep in mind that although weight training has traditionally been reserved for men it is important for women, who tend to lose muscle mass at a rate of 1% per year in their late 30’s and 40’s. This muscle mass gets replaced by fat and the fat tends to leave the subcutaneous tissue and migrate to the core as we age. The other advantage is in the delayed onset of osteoporosis/osteopenia in women and men with weight-bearing resistance exercise. Muscle acts as a cushion against injury while giving the body a trimmer, tighter appearance.

The common misconception

Circuit training isn’t just for women. It does not mean using light dumbbells and no rest periods.  The misconception that lifting heavy weights with few repetitions is the only way to increase strength holds no water in this instance. Especially considering the overweight and deconditioned individuals currently seen in the health club environment. One only has to attend meetings to notice the new emphasis on the deconditioned and aging population entering the health club arena.

However, muscle responds to the total tension produced. Using lighter weights with more sets during a set period of time will produce the same if not more total tension and will stimulate muscle growth.

The benefits

First, it allows work on the cardiovascular system while simultaneously working on strength. Since the participant is constantly progressing through the workout, the heart rate will remain elevated, therefore reaping the same benefits as the person who mindlessly logs all those miles on the treadmill. This type of training is far superior to steady-state exercises when it comes to increasing your VO2 (the amount of oxygen one can uptake during exercise). Take not that I did not say VO2max as this type of training requires very high intensity and is reserved for well-conditioned, healthy athletes. This approach will constantly stimulate the mind which will keep boredom at bay. It is also important to be mindful of performing long-duration, moderate intensity exercise, as this may put the participants in a catabolic state where they will start losing muscle mass. That’s right; some of that hard-earned muscle will start degrading itself in the quest to get lean. Hence the importance of determining appropriate intensities through metabolic testing. Determining VO2 at various intensities and aerobic threshold among other variables will allow safe, effective and results driven activity. Monitoring intensity and recovery with a heart rate monitor will enhance outcomes and provide an additional motivating variable to the participants.

The effects on specific muscle fibers should also be considered. Slow twitch muscle fibers are more compatible with short, intense bouts of exercise such as sprinting (Spinning), and weightlifting.

When training in one of these modes the muscle tissue has a tendency to take on the appropriate properties. As an illustration, imagine a marathon runner and a sprinter. The sprinter is composed of fast twitch muscles and carries a great deal more muscle mass, whereas the marathon runner has a lot of thin, slow twitch muscle fibers and their body tries to become as light as possible so that it is easier to transport across those great distances. This maybe extreme to prove a point; however it is easy to see how much of a difference the type of training has on body shape.

Second, due to fewer rest periods, there will be a greater release of testosterone which helps the muscle to grow. While it is true that if one was to perform a long aerobic session, the testosterone level will drop and the release of cortisol (which causes the body to break down muscle tissue), this workout session will not take that long to complete. Therefore, the time required to start this cortisol-releasing process will not be reached. Finally, since the participants move through the workout quickly, they will not have to spend long hours in the gym, and will be able to spend more time doing the things they never seemed to have time to do or have the energy to do.

Here are some examples of circuits that you may try members:

High intensity, short duration

  • This version of aerobic work is done around anaerobic threshold as determined by metabolic testing vs. antiquated formulas that misrepresent appropriate heart rates.
  • This is a very demanding form of training.
  • It is done for between 5 to 20 minutes generally, depending on the fitness level and

Aerobic interval training

  • The first way of doing aerobic interval training involves doing a period of moderate to high intensity aerobic work, alternating with a period of rest of low intensity work, e.g. 3 minutes of fast running then 1 minute of slow walking, repeated 4 times.
  • You can vary the intervals and intensities to your liking, e.g. 10 minutes of moderate work, 2 minutes easy, 1 minute hard, or perhaps 5 minutes hard, 5 minutes easy
  • The key is variation during the work while not working so hard that the participants must stop completely.

Anaerobic interval training

  • This type of training involves going hard for short periods of time then resting for equal or longer periods of time.
  • It is done at intensities of 85-100% max HR.
  • Here is an example of how it works: have participants sprint as hard as they can for 30 seconds, walk for 30 seconds, sprint for 30 and walk for 30 etc. Repeat 3 – 6 times depending on the fitness level of participants. If the group is mixed give specific intervals depending on their current level of fitness. This works well for Spinning classes.

Fartlek training

  • Translated from Swedish, this means speed play
  • Basically, mix up all the above types of training into one session. E.g. run for 10 minutes, sprint for 30 seconds, walk for 2 minutes, run fast for 2 minutes, jog slowly for 5 minutes then sprint again.
  • It is a good way to work through the entire intensity spectrum as well as prevent boredom.

Apply to circuit training

  • Circuit training is basically aerobic weight training
  • Set up a number of stations with a variety of exercises that work the entire body, e.g. bench, curls, pulldowns, leg curls, etc.
  • Use a fairly light weight that can be lifted without going to failure for a preset period of time.
  • Do each exercise continuously for a specified time internal e.g. 1 minute at each station and go through the cycle 1 to 3 times or more. The time to get to the next station is the rest interval. Add a cardio station or two for variety etc.
  • It is a reasonably good way to do aerobic work and weight training simultaneously.
  • It also has the advantage of working the entire body in a short period of time, incorporating both aerobic and anaerobic training.


  • 30 seconds of squats
  • 30 seconds on a stationary bike, or jogging in place or on a treadmill
  • 30 seconds of lunges
  • 30 seconds of cycling or jogging
  • 30 seconds of chest press
  • 30 seconds of cycling or jogging
  • 30 seconds of bent-over rows
  • 30 seconds of cycling or jogging
  • 30 seconds of shoulder press
  • 30 seconds of cycling or jogging
  • 30 seconds of bicep curls
  • 30 seconds of cycling or jogging

Creativity is a wonderful thing! Circuit training allows the fitness professional to create an environment to challenge the beginner as well as the advanced fitness participant even within the same class or studio environment. Circuit training will also allow for immediate success vs. failure which will keep participants coming back for more with a renewed enthusiasm for exercise, fitness and fun.

A final note

Since circuit training may not target all the muscles in the body (including the heart), it is still best to include normal strength and cardio training routines into the members programs. This lends itself to periodization methodology, keeps the body balanced, fit and healthy. Circuit training can be used to break plateaus as well. When members are feeling stale or they are not losing the fat they want use circuit training to jump-start their metabolism and excitement. Since circuit training can be quite intense have members start with once a week adding a session each week until they can perform the circuits 3 times a week. Any more than this may lead to injury and overtraining.

Stephen A Black, DSc, M.Ed., PT, ATC, CSCS is considered a world-renowned leader in the field of sports medicine, rehabilitation, fitness, and sports performance. As a physical therapist, athletic trainer, and certified strength and conditioning specialist, Stephen uses his background in sport biomechanics, movement quality, muscle imbalance, and manual therapy to specialize in all aspects of human performance. Dr. Black is the founder of Rocky Mountain Human Performance Center.

MFN Contributing Author; MedFit Education Foundation Advisory Board