In Defense of the Metabolic Circuit

Ah, the ’80s and ’90s—a time when muscle suits weren’t used by action heroes, the fullback was an integral part of the offense, and Nebraska dominated the college football landscape. Due to the Nebraska football program’s success, many people started to look at what separated them from the rest of the pack. How did they create these monsters on the field? The answer: good recruiting paired with proper strength and conditioning.

One key aspect of Nebraska’s program was the metabolic circuit, a man-maker of a workout designed to maximize hypertrophy while challenging the athlete’s conditioning. The circuit was used for many years with great success, and it quickly spread to programs across the country. However, at the turn of the 21st century, the circuit began to fall out of favor. Whether due to a lack of understanding, a conflict of vision, or poor execution, the circuit has been misused, abused, and cast aside in recent years.

While I do not believe that the metabolic circuit is the ‘king of all lifting programs,’ I do believe that it is a valid training protocol for athletes, says @Tate_Tobiason. Share on X

It pains me today to see how the metabolic circuit has fallen out of favor in some circles, as one of my integral mentors, Mike Arthur, was among the coaches who helped form and optimize it. While I do not believe that the metabolic circuit is the “king of all lifting programs,” I do believe that it is a valid training protocol for athletes and should be treated with consideration. On its surface, the circuit may look simple—and maybe even unscientific—but once you dive in, you’ll find there’s more to it than meets the eye.

What Is the Metabolic Circuit?

Dr. Bill Kraemer developed the metabolic circuit (or “Husker Power Circuit”) in conjunction with Nebraska Strength Coach Boyd Epley. The original circuit concept resembled a Tabata workout, with workouts crushing the athlete with 20 seconds of work and only 10 seconds of rest. However, with the help of Kraemer’s research and Epley’s firsthand experience, the circuit was tweaked over the years to maximize its effectiveness. The goal of the circuit is to induce a neuroendocrine and metabolic response from training, maximizing muscle-building.

The circuit consists of 8-10 exercises covering all major muscle groups, performed for 2-3 sets of 10 repetitions before moving on to the next exercise. Sounds easy enough, right? Now include an 80- to 90-second running clock, and the workout becomes a whole new monster.

The circuit begins with the squat or a comparable compound lower-body movement such as a leg press, belt squat, or trap bar deadlift. Note that growth hormone and testosterone levels increase more with free weight exercises than with machine exercises when performed at the same intensity.¹ Following the squat is a series of non-repeating muscle groups, focusing on the larger muscle groups first and finishing with single-joint movements at the end.

Example metabolic circuit:

1. Squat
2. Glute-ham-raise
3. Bench press
4. Cable row
5. Lunges
6. Pulldown
7. Shoulder press
8. Bicep curl
9. Tricep pushdown

or

1. Leg press
2. Bench press
3. Leg curl
4. T-bar row
5. Shoulder press
6. Leg extension
7. Chin up
8. Dips
9. Hammer curl
10. Calf raise

As you can see, you can perform the metabolic circuit many ways. But the primary principle is to start the workout with a compound lower-body movement and alternate muscle groups while covering every key movement pattern and muscle group in the body.

Within the Husker Power training plan (power-strength split), athletes perform the circuit twice a week, with a “heavy” strength session and a “light” strength session. Loading parameters should be challenging but manageable for the lifter, allowing them full range of motion with the ability to complete every set. Remember it is better to undershoot (T1 error) and raise the weight later than overshoot (T2 error) and visit the trainer. Sets across loading is recommended for its ease in group settings; however, you can utilize step loading if organized properly. Light days are a 10% reduction in total load from heavy days. The circuit is used in the off-season for 3-6 weeks for mid- to upper-level lifters.

Example week setup:

• Monday – Heavy power (clean and weighted jumps)
• Tuesday – Light circuit (3×10 @50%)
• Wednesday – Off
• Thursday – Light power (snatch and med ball throws)
• Friday – Heavy circuit (3×10 @60%)

Critiques

When discussing the metabolic circuit with fellow coaches, one critique I commonly hear is that the rest periods are too short—thus, they don’t allow the weights used to create a high enough tension. This is a valid argument and gets into the mechanical versus metabolic hypertrophy argument. However, I counter this argument with: Why do we chase the numbers on the bar to maximize hypertrophy, especially for athletes? Could there be a better way that raises other qualities while maximizing hypertrophy?

We should not reduce programming for athletes to a single-factor analysis argument. We can and must attempt to raise multiple qualities together. Of course, I will concede that there may be better ways to induce hypertrophy, and if that was all we were chasing, we could just implement Dorian Yates’ single set of 6-8 heavy reps to failure and see success. However, the case for the metabolic circuit, or any athletic training program, must go beyond a single factor such as hypertrophy.

Another critique of the circuit I occasionally hear is that its volume, intensity, and rest periods put athletes at a greater risk of rhabdomyolysis. I counter this argument with: Why, yes, they do. Athletics is all about pushing the limits of what the athlete can physically do. If we push too hard, bad things can happen. But on the flip side, if we push too little and fail to prepare them, I’d argue that even worse things can happen.

If you choose to implement the metabolic circuit, you must ramp up within the circuit’s parameters. Start with two sets and lower the weight initially, but don’t stay there too long. The body is amazing in its ability to adapt.

Hypertrophy Benefits

The primary benefit of the metabolic circuit is metabolic hypertrophy. The circuit works by elevating growth hormone, following high-volume programming (2-3 x10), and training with short rest periods (60 seconds).² By utilizing heavy resistance, high repetitions, and low rest, and involving many muscle groups, the circuit starts a cascade of anabolic hormones priming the body for maximal muscle growth.

By utilizing heavy resistance, high repetitions, and low rest, and involving many muscle groups, the metabolic circuit starts a cascade of anabolic hormones priming the body for maximal muscle growth. Share on X

The circuit is extremely effective at building muscle while simultaneously lowering body fat. It is not uncommon for an athlete to gain 5-10 pounds of muscle while in this phase. This isn’t “bodybuilding” muscle, but rather “armor-building” muscle: muscle mass that protects the body, not muscle mass that is all show and no go. The metabolic circuit can help an athlete not only look more like Tarzan, but also play more like Tarzan.

Conditioning Benefits (Peripheral Heart Action Training)

The metabolic circuit goes beyond being a meathead muscle-building circuit. By utilizing short rest periods and peripheral heart action training, the metabolic circuit provides a unique conditioning aspect.

Peripheral heart action (PHA) training was developed by Dr. Arthur Steinhaus and made popular by bodybuilder Bob Gajda in the 1960s. The idea is to shunt blood up and down the body, taxing the cardiovascular system to a high degree. This is believed to lead to improved metabolic rates, cardiac performance, hormonal release, and fat reduction. No two body parts are performed consecutively within the series. PHA training is intense and should only be used by experienced lifters with no risk factors.

Time Efficiency Benefits

Time is a precious commodity when it comes to training athletes. Many hypertrophy programs rely on maximal mechanical tension and can take a long time to complete. By contrast, the metabolic circuit takes an athlete under 45 minutes to complete. At its highest volume—3 sets of 10 reps for 10 exercises—the circuit takes about 40 minutes to complete (excluding the warm-up).

In addition, when used within a power-strength training split, coaches are able to program clear-cut training days with non-competing training goals. The circuit can be a very useful tool for coaches with limited time and resources.

Who Should Use the Circuit

Coaches should not use the metabolic circuit for novice or advanced athletes. In the context of the collegiate setting, freshmen should spend 6-12 months learning the basic barbell movements along with adequate conditioning before ever attempting the circuit. Furthermore, by the time an athlete reaches their senior year and beyond, the circuit may have exhausted its training effectiveness, and at this point the athlete needs to focus on maximizing the usefulness of their muscle mass as opposed to building it. The circuit is ideal for the intermediate athlete looking to build quality muscle mass. With a solid training background, they will have a fighting shot at completing the circuit.

The metabolic circuit is ideal for the intermediate athlete looking to build quality muscle mass. With a solid training background, they will have a fighting shot at completing the circuit. Share on X

The metabolic circuit was originally developed for football players looking to build what Dan John termed “armor-building” muscle. Other sports can benefit from the circuit, but the coach must use discretion. A hammer thrower looking to gain weight in the hope of increasing his distance may benefit from the circuit, but a senior hurdler looking to shave time off of their event probably will not. The coach must discern whether or not muscle mass will assist in the training goal.

Variations on the Circuit

I have never been one to be dogmatic about training programs, but rather prefer to use programs as starting points in training that I can mold and adapt to various training needs. One of the worst things a coach can do is treat every athletic program like a Russian 29-24-31-14% specific load split.

Variation #1 – Survivor Circuit

The Survivor Circuit takes the principles of the metabolic circuit but changes the exercises to become a general physical preparation circuit. Instead of muscle groups, it uses various GPP exercises such as battle ropes, prowler pushes, and lunges. The circuit can be performed set style, where athletes complete all three exercises before moving on, or in a rolling set fashion, where athletes move from station to station, completing the circuit 2-3 times. This variation is great for athletes who do not require much muscle mass but can benefit from GPP training. A coach can choose to either use prescribed repetitions or reps for time in this variation.

Example Survivor Circuit:

1. Prowler push
2. Farmers walk
3. Barbell row
4. Walking lunge
5. Battle ropes
6. Jump rope
7. Tire flips
8. Suitcase carry
9. Med ball toss
10. Push-up 

Variation #2 – Core Lift 5s

Back when I interned under Coach Epley and Coach Arthur, I learned about a circuit variation they used with upper classmen. They began the workout with 3×5 on squat, bench, and RDL, followed by 3×10 on the accessory exercises. This allows for heavier loads while still taking advantage of the growth hormone spike from 3×10 training. This method is also a great way to transition from the comparatively lighter weights of the circuit to the heavier weights of a strength training phase.

Variation #3 – Fluid Squat

This variation allows for fluidity in squat sets/reps/methods followed by a 3×10 circuit. I have used this variation by taking clusters on my squat or pause reps on my squat, or by performing Westside-style speed squats before the remainder of the circuit. It’s a fun way to mix up training and avoid monotony as you or your athletes progress.

Variation #4 – Squats off the Clock

Another way to maximize the hormonal cascade is to perform squats off the clock or without a running clock and work up to a max set of 10 around 75% 1RM. Once completed, the athlete enters the circuit as normal, with a running clock of 80-90 seconds.

Tips and Tricks

If you want to execute the metabolic circuit, here are a few tips and tricks to help the circuit go smoothly.

1. 1. Organize the circuit so that you travel from one end of the weight room to the other. Do not have players zigzag all over the weight room, leading to mass confusion. Have a coach at each major lift station with interns filling in at the single-joint stations.
   2. Perform the circuit with a rolling start, where athletes of similar strength pair up in groups of 2-3 and go through the circuit together. Organize the groups similarly to a lifting meet, with on-deck and in the hole. This will help the circuit roll through smoothly and provide clarity on who is spotting.
   3. Do not bench press unless you have sufficient spotters. Do not allow athletes to spot each other, as they will be too tired at this point in the session to safely spot. Instead, perform push-ups, pin presses, or machine/cable presses. If you do desire a barbell bench variation, raise the bench to its lowest possible incline and raise the catches to right below the chest. If the athlete must bail on the lift, they can do so safely with the bar rolling from the chest onto the catch bars.

Try It, Then Decide

The metabolic circuit is a powerful tool for any athlete looking to add quality muscle mass in the off-season while also providing a conditioning aspect utilizing PHAT principles. It is more than a single-factor workout, but rather a maximizer of multiple factors.

The metabolic circuit is a powerful tool for any athlete looking to add quality muscle mass in the off-season while also providing a conditioning aspect utilizing PHAT principles. Share on X

I personally love the metabolic circuit and use it and its variation not only with my athletes, but also in my own training. It is a gut check of a workout that will make you better on the other side. So, give it a try. See how you like it. Try some variations. If you don’t like it, great—move on to the next program. If you like it, I hope your athletes forgive you after the first week of implementation.

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References

1. Shaner, A. A., Vingren, J. L., Hatfield, D. L., Budnar, R. G., Jr, Duplanty, A. A., and Hill, D. W. “The acute hormonal response to free weight and machine weight resistance exercise.” Journal of Strength and Conditioning Research. 2014;28(4):1032–1040.

2. Kraemer, W. J., Marchitelli, L., Gordon, S. E., et al. “Hormonal and growth factor responses to heavy resistance exercise protocols.” Journal of Applied Physiology. 1990;69(4):1442–1450. https://doi.org/10.1152/jappl.1990.69.4.1442