Some say that metabolic resistance training, or metabolic training for short, is one of the best ways to build muscle, torch fat and improve your overall fitness… all at the same time.
Your metabolism will be spiked, fat will be incinerated and metabolic forces that work day and night to change your body will be unleashed.
Or will they?
In this article, I take a closer look at the science behind metabolic workouts, and explain why many of the benefits ascribed to metabolic resistance training can be achieved with standard, vanilla, run-of-the-mill, non-metabolic resistance training.
More about that in a moment. First, what is metabolic training?
What is Metabolic Resistance Training?
Metabolic training is a form of circuit training that targets the entire body. You do several exercises back to back, usually with very little rest (30 seconds or less) in between.
A typical workout involves working through a series of compound exercises, usually with your own bodyweight or free weights serving as a resistance.
One of the main aims of metabolic training is to maximize the number of calories you burn both during and after your workout.
The metabolic workout in the video below, for example, involves working intensely for 20 seconds before resting for 10 seconds.
Here’s what a standard metabolic workout might look like:
Push Ups [30 SECONDS]
Rest [15 SECONDS]
Jump Squats [30 SECONDS]
Rest [15 SECONDS]
Wood Choppers [30 SECONDS]
Rest [15 SECONDS]
Mountain Climbers [30 SECONDS]
Rest [15 SECONDS]
Speed Skaters [30 SECONDS]
Rest [15 SECONDS]
Renegade Row [30 SECONDS]
After completing the circuit you’d take around two minutes of rest before doing the whole thing again. In total, you’d do two or three rounds to complete your workout.
Is Metabolic Resistance Training The Same as HIIT?
While they do have a few things in common, HIIT and metabolic resistance training aren’t the same thing. HIIT, short for high-intensity interval training, usually refers to cardio such as running or cycling.
Metabolic training, on the other hand, typically involves multi-joint exercises done with free weights (barbells, dumbbells or kettlebells) or your own bodyweight.
They do have similarities, in the sense that there are peaks and valleys, where you go hard before backing off.
Both types of exercise have also been shown to deliver similar gains in VO2max – a marker of cardiovascular fitness – to steady-state cardio, with workouts that are much shorter.
In one month-long study, four minutes of “whole-body aerobic-resistance training” improved VO2max to the same extent as 30 minutes of steady-state cardio .
Metabolic Resistance Training for Muscle Growth
One of the claims made about MRT is that full-body metabolic workouts will produce more growth hormone, so you build more muscle.
Here’s an example of the type of thing I mean:
Metabolic training uses compound exercises with resistance at high intensity. This recruits and exhausts more muscle and naturally triggers the release of growth hormone which is key in increasing muscle mass. During pretty much every metabolic training session you’ll feel your muscles burning. That is an indication of an internal process of releasing a cocktail of hormones to build up those muscles to be stronger next time.
There are several things about this claim to unpack, so let’s start at the beginning.
First, it’s true that full-body workouts, especially those where the amount of rest between sets is relatively short, do lead to a short-term spike in growth hormone levels.
One of the first studies to look at the impact of different workouts on growth hormone was published back in the 1990’s .
To find out how different set and rep configurations affected post-workout hormone levels, the researchers rounded up a group of men and put them through a number of different workouts. In essence, they compared a strength-type workout with a hypertrophy-type workout.
The strength-type workouts involved heavy weights, low reps and three minutes of rest between each set, while the hypertrophy-type workouts were done using lighter weights, higher reps and 60 seconds of rest between sets.
- Bench press 5 sets x 5 reps
- Leg extension 5 sets x 5 reps
- Military press 3 sets x 5 reps
- Bent leg, incline sit-ups 3 sets x 5 reps
- Seated row 3 sets x 5 reps
- Lat pulldown 4 sets x 5 reps
- Arm curls 3 sets x 5 reps
- Leg press 5 sets x 5 reps
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- Bench press 3 sets x 10 reps
- Leg extension 3 sets x 10 reps
- Military press 3 sets x 10 reps
- Bent leg, incline sit-ups 3 sets x 10 reps
- Seated row 3 sets x 10 reps
- Lat pulldown 3 sets x 10 reps
- Arm curls 3 sets x 10 reps
- Leg press 3 sets x 10 reps
It was the hypertrophy-type workout that triggered the largest rise in growth hormone levels. In fact, the post-exercise rise in growth hormone was around eight times greater compared to the strength-type workout.
However, this wasn’t really a metabolic workout. There were no burpees. No kettlebell swings. No mountain climbers. It was a just a bog standard hypertrophy-type workout, with all but two of the exercises done on a Universal weight machine.
In other words, even with a standard non-metabolic workout geared towards muscle growth, you can still expect to see a post-training rise in growth hormone levels.
Metabolic Resistance Training Might Increase Growth Hormone, But Does it Matter?
While a full-body metabolic workout might increase growth hormone levels, this won’t make a difference to the rate at which muscle is gained.
In fact, we’ve known for a while that any temporary surge in post-training hormone levels is too small to have any impact on muscle protein synthesis , muscle fiber hypertrophy  or strength gains .
Even growth hormone injections don’t do much for the synthesis of muscle protein, a prerequisite for building muscle.
Back in the 1990s, Kevin Yarasheski, a Professor of Medicine at Washington University School of Medicine, took a group of healthy young men, and injected them with growth hormone for two weeks .
He found that muscle protein synthesis was identical to the rates measured before treatment. Protein breakdown was also no different before or after the injections.
In short, growth hormone isn’t a particularly effective drug for muscle growth. Most of the gains in lean mass are accounted for by changes in fluid levels in the body [6, 7]. Even in healthy, elderly men, growth hormone administration has little, if any, effect on muscle size and strength .
If GH injections, which produce a large and sustained rise in growth hormone levels, don’t do much for muscle growth, the temporary spike you get after exercise is unlikely to do much either.
That is, while a full-body metabolic workout may increase growth hormone levels to a greater extent than a strength-type workout, that doesn’t mean you’re going to build muscle any faster.
Metabolic Workouts: Compound vs Isolation Exercises
Metabolic workouts are also said to be better than traditional weight training routines because of their emphasis on compound rather than isolation exercises.
Here’s an example:
Using isolation exercises will not help you gain muscle quickly because you can’t really use the most weight possible with isolation exercises. In fact, you’ll use less weight because it’s harder to lift heavier weights when you’re isolating your muscles.
This is something you hear a lot.
Chin-ups, for example, are supposed to be better than curls for making your biceps grow, because you’re lifting your entire bodyweight. That’s a lot more than most people can pick up and curl.
However, this fact alone doesn’t make curls less effective than chin-ups for building your biceps.
The reason you can lift more weight during an exercise like the chin-up compared to a dumbbell curl is because multiple muscles are doing the work.
With the dumbbell curl, it’s mainly the biceps moving the weight. But with the chin-up, the muscles in your back, shoulders and biceps are all involved.
The work is being distributed across multiple different muscles, which is why you can lift more weight.
Single-joint exercises will involve the use of lighter weights compared to compound lifts. But that’s because fewer muscles are involved. It doesn’t necessarily mean they’re less effective than multi-joint movements for stimulating growth in a particular muscle.
Does Metabolic Resistance Training Build Muscle?
As long as your training program is set up properly (meaning that each muscle group is being trained with enough volume, frequency and effort to make it grow) then metabolic training will certainly lead to some muscle being built.
But is it going to do a better job at stimulating growth than regular weight training? No it’s not.
Rushing from one exercise to the next, doing burpees, jump squats, kettlebell swings, mountain climbers and whatever else is a long way from being the best way to train for hypertrophy.
It’s certainly a lot less effective for building muscle than regular resistance training, where you’re lifting heavier weights, giving yourself plenty of rest from one set to the next, and where muscular (rather than cardiovascular) fatigue is the limiting factor when it comes to the number of reps you’re able to do.
Metabolic Resistance Training and Fat Loss
Metabolic workouts are also supposed to be better than traditional weight training routines for losing fat. Specifically, metabolic workouts are thought to increase excess post-exercise oxygen consumption (EPOC for short), which you’ll often see referred to as the afterburn effect.
Here’s the type of claim you might come across:
After a metabolic workout your body’s metabolism is very high. Because you are resting at this time, your body is tapping into your fat stores for energy through oxygen. Oxygen burns fat. Your body takes a lot longer to recover after metabolic workouts, therefore your body is burning fat for a longer period. Science shows that your body can burn fat up to 36 hours after an HIIT workout (metabolic or Spartan) – that’s great!
It’s true that more intense workouts tend to generate a bigger afterburn effect than workouts of the low-intensity variety. This means that more calories are being burned in the hours after your workout is over. However, the size of the afterburn effect, as well as the extent to which it contributes to fat loss, isn’t as great as was once believed.
There was an interesting paper published in the British Journal of Sports Medicine, where researchers pooled the results from multiple trials on the subject of HIIT, steady-state cardio and fat loss .
HIIT typically generates a much larger afterburn effect than steady-state cardio, which is one of the reasons it’s supposed to accelerate fat loss compared to exercise of a lower intensity.
What did the researchers find?
After crunching the numbers, HIIT did provide a “greater reduction in total absolute fat mass” than steady-state cardio.
However, while the difference between HIIT and steady-state cardio was statistically different, the “real world” difference was small.
After 30-35 workouts (10-12 weeks if you’re training three times a week), the average amount of fat loss with HIIT was 3.5 pounds (1.58kg), compared to 2.5 pounds (1.13kg) with steady-state cardio.
Granted, the HIIT workouts didn’t last as long. But the overall difference in fat loss between the two types of exercise – one pound of additional fat loss over a 10-12 week period – was relatively small.
Strength Training for Fat Loss
A number of articles on the subject of metabolic training and fat loss cite a 2002 study as “proof” that MRT elevates your metabolism for 38 hours .
The paper, published by a team of researchers from the University of Wisconsin-La Crosse, does indeed show that a single workout comprising just three exercises – the bench press, parallel squat, and power clean – led to an increase in resting metabolism that was still measurable almost two days later.
Here’s what the workout looked like:
Bench Press: 8-12 repetitions
Rest: 2 minutes
Power Clean: 8-12 repetitions
Rest 2 minutes
Squat: 8-12 repetitions
Rest 2 minutes
The circuit was completed a total of four times.
One of the defining characteristics of metabolic training is taking “little (i.e. under 30 seconds) or no rest” between sets.
However, the study in question involved taking a full two minutes of rest between sets, not 30 seconds or less.
To quote the researchers directly:
“Each lift was performed until failure, and 2 minute rests were given between sets. Loads were adjusted after each set to maintain 10 repetitions on subsequent sets.”
In other words, this wasn’t metabolic training. It was plain old weight training.
Why I Don’t Do Metabolic Resistance Training
Metabolic training does have several benefits – it burns lots of calories, and can improve your cardiovascular fitness. The workouts themselves are also relatively short, and can be done with little or no equipment.
Personally, I don’t like metabolic resistance training, so I don’t do it.
I much prefer to take my time and get a decent amount of rest between each set before tackling the next one.
Not only do you get many of the benefits of so-called metabolic training with standard resistance training, the number of calories that a given workout burns is not the only or even most important criteria by which to judge its effectiveness.
There are two other things that are far more important:
1. Your ability to stay consistent.
Your ability to stick with a particular program of diet and exercise trumps everything else when it comes to getting in shape.
So, you need to pick a type of exercise/activity that you like (or dislike less than everything else).
If you hate a particular type of exercise, chances are you’re not going to be doing it long enough to see results.
2. The ability of said program to stimulate the acquisition (or even just the retention) of muscle mass while you drop fat.
For most people, getting in shape means having more muscle and less fat.
Metabolic training will do a better job than regular cardio as far as building/maintaining muscle mass is concerned.
But, there are better options out there.
The last time I got in “photoshoot” condition, I had no idea how many calories I was burning each time I trained.
That’s because the goal of each workout wasn’t to burn calories. It was to send the “size and strength” stimulus to my muscles.
Granted, getting ripped while simultaneously building a lot of muscle doesn’t happen unless you’re using a lot of drugs. But, at the very least, I wanted to hold on to the muscle I’d already built.
And the type of training that works best for retaining muscle is much the same as the type of training that works best for gaining that muscle in the first place.
In other words, a training program that normally makes a muscle grow will, under the right conditions, work to preserve that muscle when you’re dieting.
Why Diet is Key to Losing Fat
When it comes to losing fat, the food you eat (or don’t eat) is a lot more important than what you do in the gym. Sometimes, a workout that burns lots of calories will stimulate your appetite, so you end up replacing the calories you’ve worked so hard to burn.
There’s also a phenomenon known as moral licensing, where being “good” gives you permission to be “bad.”
In other words, you could end up eating more food after a high-calorie workout because you feel like you “earned” it.
As a result, all the fat you’ve just burned off will end up getting replaced. Metabolic training may very well make you fitter, stronger and more muscular. But, if you don’t get your diet right, it’s not going to make you any leaner.
Back in the day, metabolic training used to be called circuit training. But use of the term “metabolic” automatically makes anything sound trendy, exciting and hardcore.
Metabolic Workout. Metabolic Training. Metabolic Conditioning.
Metabolic training is just a fancy name that people are using to “dress up” an old training method and pass it off as something new.
It also means that trainers can run around spouting off various three-letter abbreviations, to show that they’re cleverer than you. Instead of calling it metabolic resistance training, they’ll refer to it as MRT. This is simply another way for them to show off.
Metabolic resistance training can burn a lot of calories in a relatively short period of time. But no type of exercise, be it HIIT, metabolic training, or whatever else is new and trendy this week, will do much for fat loss compared to not eating certain foods.
The main goal of lifting weights is to stimulate your muscles in such a way that they come back a little bigger and stronger the next time you train. Burning calories is simply a side effect of doing the work necessary to achieve that goal. It’s not the end in itself.