Illustration of a bodybuilder training with the X3 Bar by Dr John Jaquish to build muscle mass.

Review of the X3 Bar by Dr John Jaquish: Is It Good for Building Muscle?

Dr John Jaquish is quickly becoming known for making extravagant claims about the benefits of training with his resistance band system, the X3 Bar. According to him, the product that he developed is the very best way to build muscle—three times better than traditional weight lifting. And not only that, it’s cheap, safe, and can be done from the comfort of your very own home.

But is any of that true? Are resistance bands an effective way to stimulate muscle growth? Is the X3 Bar better than the other types of resistance bands? And how does it compare to traditional weight lifting for building muscle? Can it really compete? Does it really offer any advantages?

So, is the X3 Bar good for building muscle? Let’s take a look.

Outlift illustration showing the before and after results of a skinny-fat guy building muscle.

What is the X3 Bar?

The X3 Bar is a bar connected to resistance bands. The resistance bands provide the resistance, the bar gives you something convenient to hold onto. The idea is that because you’re holding a barbell-like handle, you can handle heavier resistance, and so you can stimulate three times more muscle growth, hence the name—X3.

Does the X3 Bar Build 3X More Muscle?

Dr John Jaquish cites this study, The Effects of Combining Elastic and Free Weight Resistance on Strength and Power in Athletes, as proof that the X3 Bar stimulates three times more muscle growth than traditional weight training. Problem is, this study investigated whether we can improve muscle growth by adding band tension to free weights (accommodating resistance), like this:

Illustration of a man doing accommodating resistance.
This is accommodating resistance. This is what was studied.

The idea with accommodating resistance is that as we get closer to locking out the weight on some of the big barbell lifts—the squat, bench press, and deadlift—the moment arms get shorter, our leverage improves, and we’re able to lift more weight. So a band is added to the barbell, adding a bit of extra resistance at the top, keeping it challenging throughout the entire range of motion.

Now, this isn’t true with all lifts. If we look at the overhead press, barbell row, chin-up, biceps curl, lateral raise, or a hundred other exercises, the resistance curve is totally different, and so adding a band to the lift wouldn’t help at all. In fact, in some of those cases, we’d want to the opposite, offloading weight as we lift the barbell higher. That’s the idea behind the T-bar row machine. As we lift the weight higher, more of the weight rests on the pivot point, keeping the lift similarly challenging throughout the entire range of motion, like so:

Illustration showing a man doing a row on a t-bar row exercise machine.
The T-bar row, designed to flatten the strength curve of the barbell row.

But anyway, that’s not what the X3 Bar does. It doesn’t use accommodating resistance (like weights + bands) and it doesn’t flatten the strength curve (like exercise machines). It gets all of its resistance from resistance bands. This is a type of resistance called variable resistance, where the lift gets progressively harder through the range of motion. We’ll cover the implications of that in a moment.

Where this gets even more controversial is that the study being referenced to show the benefits of the X3 Bar didn’t even find a benefit to adding resistance bands to traditional weight training lifts. The study concluded, “While lean body mass was not significantly different between groups, both groups did significantly increase their lean body mass over the course of the study.”

Graph showing the differences in muscle growth between resistance bands and exercise machines, with the authors concluding that there were no statistically significant differences.

Dr Jaquish does cite one study that used resistance bands, though. It took a group of sedentary middle-aged women and compared their muscle growth after 10 weeks of either using resistance bands or exercise machines. The problem is, again, the study failed to prove that there was any benefit to using resistance bands over exercise machines. The women using the exercise machines gained twice as much lean mass and lost twice as much fat, but the results didn’t reach statistical significance, and so we can’t draw any conclusions.

With that said, none of this proves that the X3 Bar is a scam or that we’ve debunked its effectiveness, just that the studies being referenced don’t back up the claims being made. Even if the X3 Bar doesn’t build muscle three times faster than free weights or exercise machines, maybe it still works comparably well. For many people, that would be enough.

Does the X3 Bar Actually Work?

If we challenge the strength of our muscles, we can provoke muscle growth. This is true whether we use bodyweight exercises, dumbbells, barbells, exercise machines, or resistance bands. All of them put mechanical tension on our muscles, and all of them can build muscle. And that includes the X3 Bar. It’s a legitimate type of resistance training. You can indeed build muscle with it.

Illustration of a man building bigger forearms with forearm workouts.

With that said, just because something works, that doesn’t mean that all the claims made about it are true. It also doesn’t mean that it’s the best way to build muscle. It doesn’t even mean that the X3 bar is a good way to build muscle. So let’s dig a little deeper.

Is Variable Resistance Good for Building Muscle?

If you want an in-depth review of the research, we’ve written an entire article on the effectiveness of resistance bands. But I can summarize the main points here, as well as give the recommendations from the top muscle hypertrophy researchers.

What makes the X3 Bar unique from free weights and exercise machines is that it gets its resistance from resistance bands. This matters because as you stretch the band out, the tension increases, providing gradually more resistance as you go through the range of motion. This is called variable resistance, like so:

Illustration explaining the variable resistance of the X3 Bar.

Thing is, there’s a growing body of evidence that when we challenge our muscles at longer muscle lengths, we stimulate more muscle growth. And the effects are quite dramatic, too. If we look at a systematic review of 26 studies, we see that challenging our muscles at longer muscle lengths stimulates almost three times as much muscle growth:

Graph showing how training at different muscle lengths stimulates different amounts of muscle growth.

Now, just to be clear, these 26 studies were done using isometric lifts. What that means is that they had some people pulling against an immovable object with their muscles in a stretched position, other people pulling against an immovable object with their muscles in a more contracted position. It’s not comparing lifts with different strength curves, it’s comparing the effects of challenging our muscles at different muscle lengths. (And again, note that even with the worst way of training, challenging their muscles in a fully contracted positions with isometric lifts, the participants were still able to gain muscle.)

So, what we see with this research is that the more stress we put on our muscles when they’re stretched, the more muscle we build. This seems to apply to traditional weight training and exercise machine lifts, too. For example, if we look at a study on hamstring curls, we see that training the hamstrings at longer muscle lengths produced a more than twice as much muscle growth as training them at shorter muscle lengths.

What does this have to do with resistance bands? Resistance bands put a lower amount of tension on our muscles when they’re at longer muscle lengths and a higher amount of tension on our muscles when they’re at shorter muscle lengths. That means that we tend to be limited by our strength when our muscles are contracted, not when they’re stretched. That’s the opposite of what we want. It’s the least beneficial resistance curve for building muscle.

Finally, there’s the claim that “X3 uses variable resistance, which effectively lowers the resistance during the lifter’s weakest range of the lift and increases it during the stronger portion.” For some lifts, such as the bench press, this is true, which is why accommodating resistance is sometimes used. For other lifts, such as the row, this is not, which is why t-bar rows are so popular. It really depends on the resistance curve of the lift. And in either case, the research still suggests that there’s a benefit to loading our muscles heavier at longer muscle lengths.

Where this gets confusing is that challenging our muscles at short lengths tends to result in higher electromyography (EMG) readings. The muscles bunch up, so more muscle mass is under the electrode, so the reading comes out higher. This is one of the problems with EMG research, and it’s why it pays to look at actual muscle growth instead of just muscle activation.

Outlift illustration of a bodybuilder flexing his biceps.

This style of high-rep, constant tension training also tends to give people a killer pump, it often feels quite hard, and it can lead to plenty of muscle soreness. It’s not ideal for building muscle, but it still feels like a rigorous way of training, and so a lot of people really enjoy it. And that’s fine. People should train however they want. But most research shows that we build more muscle by emphasizing mechanical tension, not by emphasizing the pump and burn.

Are Resistance Bands As Good as Free Weights?

So far, my hunch is that free weights and exercise machines are better for building muscle, but maybe I’m missing something. So I talked with one of the top experts in the world, Dr Eric Helms.

Not a lot of research on the topic, but I would agree with your general recommendations of free weights and machines for hypertrophy, with bands and bodyweight working in a pinch.

Dr Eric Helms, PhD

You may be familiar with Dr Helms already. He’s published several important studies looking into muscle hypertrophy, such as this one. He also the co-author of the Muscle & Strength Pyramids, which has been praised by other top hypertrophy researchers, such as Dr Brad Schoenfeld and James Krieger, MSc.

For another perspective, I asked Greg Nuckols, MA. Greg is the founder of Stronger by Science, he’s the creator of the research review, Monthly Applications in Strength Sport (MASS), and he’s the guy who turned me onto the research showing that our muscles grow better when we challenge them at longer muscle lengths.

Yeah, I do think, in general, bands are probably slightly worse for growth since it’s a lot harder to load a muscle at long muscle lengths.

Greg Nuckols, MA

Is any of this conclusive evidence that free weights are better than resistance bands for building muscle? No. That evidence doesn’t exist. But what’s abundantly clear is that there’s no reason to suspect that resistance bands are better for building muscle. In fact, most research suggests and most experts suspect that the opposite is true.

What About the X3 Exercises & Workout Routine?

Every exercise is a little bit different, and the X3 bar will be better at some than others. And just to be clear, this isn’t a horrible way to train. This is resistance training. It will build muscle. But if we look at a lot of these exercises, because of the variable resistance, the range of motion gets really short, and it’s typically the bottom part that gets cut off.

For example, if we look at the X3 chest press, we see that they’re using a very narrow grip (which is bad for the chest) and a shallow range of motion (which is really bad for the chest). To build a bigger chest, better to do the opposite of this, using a wider grip and bringing the barbell all the way down to the chest. That way the chest is trained under a deep stretch, stimulating something like twice as much muscle growth.

But again, if we look at the research comparing training at longer vs shorter muscle lengths, it doesn’t show that it’s impossible to build muscle by training at shorter muscle lengths, just slower. So if all you have is an X3 Bar, that’s okay, just be patient with it. You can still build muscle.

Is the X3 Bar As Good As Weight Training?

So, overall, we have a large body of evidence showing that loading our muscles heavier in a stretched position can stimulate 2–3x more muscle growth than loading them when contracted. This suggests that free weights are better for building muscle than resistance bands, although there’s no research looking at it directly. We also have the top hypertrophy researchers and reviewers suspecting that resistance bands are worse for building muscle.

What does this mean for the X3 Bar? Well, the X3 Bar is a metal bar connected to resistance bands. It’s a slightly more convenient way to use resistance bands. And just like resistance bands, we can indeed use it to build muscle. But because of the variable resistance, I’m doubtful that it can build muscle as effectively as using dumbbells, barbells, or exercise machines.

Illustration of Milo of Croton carrying a calf as it grows into a bull, demonstrating the principle of progressive overload.

I’d also argue that barbell and dumbbell training is actually quite easy and convenient. We’re lifting real objects, which feels quite natural and intuitive. Weights have a resistance curve that we’ve evolved to be good at lifting. And it’s easy to load those weights gradually heavier, adding tiny little weight plates to the bar over time. That doesn’t mean that free weights are necessarily ideal, but so far nothing has proven to be significantly better.

If you don’t have the money or the space for a barbell home gym, you can always get a couple of adjustable dumbbells that you can hide under your bed or stick in the closet. That’s how I would train when I lived in a small condo. There isn’t really a problem that needs solving. Except, perhaps, for the fact that free weights are so popular right now that they’re sold out everywhere.

What About Going Beyond Failure?

There’s more to the X3 Bar than getting the resistance from resistance bands. For example, one of the other ideas is to keep lifting long past the point of muscle failure. When you can’t complete a full rep, you do half a rep. When you can’t complete half a rep, you do a quarter rep. And so on. You keep pushing until you can’t stretch the band at all.

Graph showing that beginner lifters build more muscle if they take their sets to muscle failure.

The idea is that by going beyond failure, we do a better job of thrashing our muscles, and so we can stimulate more muscle growth. So far, the evidence points in the other direction. As beginners, we can build more muscle by pushing ourselves as little harder (studystudystudystudy), but then as intermediate lifters, it helps to stop our sets shy of failure (studystudystudystudystudy).

Graph showing that intermediate lifters build more muscle if they stop their sets shy of muscle failure.

Now, there’s a bit of nuance here. Different lifts are hardest at different parts of the range of motion, meaning that training to failure can look quite different depending on which lift you’re doing. With a bench press, the lift gets a little easier towards the lockout. People are more likely to fail with the bar close to their chests. So with a bench press, when you’re done, you’re done.

Illustration of a man doing the bench press to gain muscle mass.
The sticking point of the bench is near the bottom, where the upper arms are horizontal.

With other lifts, such as the barbell row, the lifts get harder at the top of the range of motion. People are more likely to fail to bring the barbell all the way up to their torsos. So it’s totally possible to do what Dr John Jaquish is recommending, where you keep lifting with a progressively smaller range of motion until you can’t lift the barbell at all.

Illustration of a man doing a bent-over barbell row to build muscle in his upper back.
The sticking point of the row is the top, where the upper arms are horizontal.

But is that a better way to build muscle? Probably not. Going past failure is hardly ever recommended, and there’s no evidence to suggest that it stimulates more muscle growth. That isn’t to say that it’s necessarily a bad way to train under all circumstances, just that there’s no reason to think that it would give you a marked advantage.

Illustration of a bodybuilder doing front squats to gain muscle mass.
A deep front squat, challenging the quads at long muscle lengths.

So, if you can, it’s probably best to choose lifts that allow you to lift through a deep range of motion and that challenge your muscles at long muscle lengths with a good resistance curve. Think of lifts like a deep front squat, a bench press, a deficit push-up, a Romanian deadlift. And then stop 0–3 reps shy of failure. That seems to be ideal for stimulating muscle growth.

What About Keto and Carnivore?

The X3 Bar isn’t just a resistance training tool, it also includes a workout routine and a diet. It recommends a meat-based ketogenic diet with minimal carbohydrates, as popularized by the orthopedic surgeon, Shawn Baker. Again, this flies in the face of most research, which shows a strong and clear benefit to the consumption of carbohydrates for building muscle.

Illustration of a chicken, a common source of protein for people trying to build muscle.

The Journal of the International Society of Sports Nutrition recommends getting 40–60% of our calories come from carbohydrates for gaining muscle mass and strength. The National Strength & Conditioning association recommends getting 45–65% of our calories from carbohydrates to improve our health, gain muscle, and increase our strength. These recommendations also line up with muscle-building research that compare different macronutrient intakes (studystudy). And if we look at expert recommendations from researchers like Dr Eric Helms, he recommends getting around 50% of our calories from carbohydrates.

Graph showing how muscle growth compares between a keto diet and a high-carb diet.

Now, how much does this matter? It’s hard to say. The higher-quality studies looking into the effects of the keto diet on muscle growth, such as this one (shown above), tend to find an advantage to eating more carbohydrates. But it’s not quite that simple. Part of the advantage is that it’s easier to eat more calories when eating more carbohydrates. That’s why other studies, such as this one and this one found that when athletes started eating a keto diet, they stopped gaining muscle mass. But even if we factor out energy intake, carbohydrates still appear to speed up our rate of muscle growth.

The reason that carbohydrates help is because our muscles prefer to run on a fuel called glycogen, which is made out of glucose, which typically comes from the carbs we eat. So the more carbs we eat, the more glycogen we store in our muscles (studystudy), and the better our workout performance gets (study). But what’s especially interesting is that having higher levels of glycogen in our muscles seems to boost our rate of muscle growth (studystudystudy).

But again, just to be sure, I asked the hypertrophy researcher Dr Eric Trexler, who specializes in muscle-building nutrition and supplementation, what he thought about the pros and cons of using keto for building muscle:

The current evidence doesn’t suggest that it’s impossible to gain muscle on a ketogenic diet, but its effects on appetite and high-intensity exercise performance make it hard to view keto as the ideal dietary approach for gaining muscle.

Eric Trexler, PhD

If you want a more in-depth review of all the relevant research, we have a full article about using keto for muscle growth. But the point is, similar to training with variable resistance, it’s not that eating a ketogenic diet can’t work, it’s just that there’s no evidence showing an advantage, and quite a bit of evidence pointing towards at least a slight disadvantage.

Can You Gain 20 Pounds of Muscle in 6 Months?

One of the criticisms that Dr John Jaquish often comes up against is his claim that when people start using the X3 Bar, they can gain 20 pounds of muscle in 6 months. I actually don’t see a huge problem with that, especially if we’re talking about it more casually, and especially if we’re talking about people who are still relatively far away from their genetic potential.

Before and after photos showing a skinny guy doing a lean bulking transformation.

For example, here’s a before and after photo showing that one of the members of our Bony to Beastly Program was able to gain 29 pounds on the scale within 5 months. Is all of that weight muscle? No. His muscles are storing more glycogen, he’s got more food in his stomach, he’s surely gained some fat, his bones are getting denser, and so on. There are many factors contributing to his weight gain. But when people see this, it’s common for them to say that he gained 29 pounds “of muscle.” It’s not true, but it looks true, and it’s just a casual way of talking about his results. I think that’s fine.

The other aspect of this is that when someone is fairly thin, they’re typically able to gain muscle at a much faster rate than someone who’s already near their genetic potential. This is why you’ll see guys gaining 20+ pounds of seemingly lean mass during their first year of weight lifting, but fast forward a few more years, and they’d be lucky to gain 5 pounds of muscle in a year. It all depends on how close to your genetic muscular potential you are.

So is it possible that someone can gain 20 pounds of what appears to be muscle when they start training with the X3 Bar? Maybe! That’s not realistic for everyone, and I’d guess that’s not the norm, but I’m sure it happens from time to time.


The central claim behind the X3 Bar is that it builds muscle three times faster than traditional weight training. Here’s the evidence behind that claim: study found that adding resistance bands to barbell training did not build more muscle than barbell training alone. I feel like this must be some sort of mistake. The research isn’t on a training method that’s similar to X3, and it didn’t find a muscle-building benefit.

Plus, if we look at the overall body of research on accommodating resistance for gaining strength, the meta-analysis that had found a benefit was retracted. When the mistakes were corrected, no benefit was found. So even when using a hypothetically optimal mix of weight training and resistance bands, the addition of variable resistance didn’t help in any measurable way.

Illustration of a bodybuilder working out and gaining muscle mass.

When we’re talking about only using resistance bands, the situation changes. When we stretch out resistance bands, they apply progressively more tension, which is called variable resistance. This is the opposite of what we want when building muscle. After all, we have several dozen studies showing that challenging our muscles at longer muscle lengths stimulates quite a bit more muscle growth. That means that it’s better to load our muscles heavier at the bottom of the range of the range of motion (as with free-weight squats, bench presses, and deadlifts) or with a flat resistance curve (as with exercise machines like the t-bar row).

Still, there isn’t much, if any, research comparing resistance bands against free weights. With the evidence available, there’s good reason to infer that free weights and exercise machines are probably better for building muscle. And this is a position shared by the top hypertrophy researchers and experts in the world. So our argument isn’t that resistance bands are bad for building muscle, just that these claims that they’re better for building muscle are misleading.

Resistance bands have been around for over 120 years, and they’re cheap, convenient, and heavily marketed. They’ve never managed to fully catch on, but some people prefer them, and that’s totally fine. Resistance bands do provide resistance, and X3 is no exception. The claims are wild and unsubstantiated, but you can still build muscle with bands.

Shane Duquette is the co-founder and creative lead of Outlift, Bony to Beastly, and Bony to Bombshell, and has a degree in design from York University in Toronto, Canada. He's personally gained 65 pounds at 11% body fat and has ten years of experience helping over 10,000 skinny people bulk up.

Marco Walker-Ng is the co-founder and strength coach of Outlift, Bony to Beastly, and Bony to Bombshell, and is a certified trainer (PTS) with a Bachelor's degree in Health Sciences (BHSc) from the University of Ottawa. His specialty is helping people build muscle to improve their strength and general health, with clients including college, professional, and Olympic athletes.