The ARX Study: What the 2021 ACE Trial Shows, and Does Not

ARX sells two machines, the ARX Alpha at $43,000 and the ARX Omni at $46,000, both verified 2026-09-17, and it sells them on one study. The headline figures on the ARX site, twice the muscle gain, 90 percent greater strength gain, 2.5 times the fat loss and 3.5 times the cardiovascular improvement in 72 percent less training time, all trace to a 12-week study at Western Colorado University that the American Council on Exercise commissioned in 2021, later published in the International Journal of Research in Exercise Physiology. Everything we track from the brand lives on the ARX brand hub.

Here is the direct answer. The study shows that in one 12-week trial, a group training on ARX twice a week for about 15 minutes was reported to outgain a group doing moderate-intensity weights for 45 minutes three times a week, on the measures ARX quotes. It does not show that the result repeats, because it is one study; that it holds for you, because it ran on one cohort at one university; or anything we have measured, because we have not tested an Alpha or an Omni. Treat the numbers as the brand's cited evidence, read the full paper before you spend $43,000, and if you buy, buy for the time saving and the per-rep force data, which the study is not needed to establish.

Quick answer

• Home buyer who wants the full ARX exercise list: the ARX Omni at $46,000, verified 2026-09-17, sixteen cable-driven exercises including belt squat, deadlift and Romanian deadlift, none of which the Alpha has.
• Home buyer who wants the smallest footprint and the easiest learning curve: the ARX Alpha at $43,000, verified 2026-09-17, six guided-sled exercises in 21 square feet for $3,000 less than the Omni.
• Buyer who needs the study to be independent proof first: neither machine yet, because the ARX Alpha at $43,000 and the Omni at $46,000 both rest on one commissioned 12-week study that ARX cites and we have not replicated.

ARX Alpha and Omni at a glance

Both share everything below the exercise list: 110V on a dedicated 20A circuit or 220V on a dedicated 15A circuit, no GFCI outlets per ARX, a complimentary one-year warranty, a typical two-to-four-week lead time, the ARX Certified Course, and a purchase that runs through a Talk to ARX call rather than a checkout. ARX does not state which footprint dimension is which.

What the 2021 ACE study is

The American Council on Exercise commissioned the study in 2021. It ran for 12 weeks at Western Colorado University and compared training on ARX adaptive resistance equipment against moderate-intensity weight training. Per ARX, the ARX group trained twice a week for about 15 minutes a session; the weight-training group trained three times a week for 45 minutes. It was later published in the International Journal of Research in Exercise Physiology. That is the whole of what our verified record carries about the design.

Adaptive resistance, the thing under test, is what both machines do in place of a weight stack: a computer-controlled motor pushes back with exactly the force you produce at every point in the rep, including the lowering, or eccentric, phase, which ARX says weights cannot load. The Alpha delivers that on a guided sled across six exercises; the Omni through a cable system across sixteen. The study is about the method, not either model.

What ARX says it found

Four outcome figures and one time figure, all ARX's: 2 times the muscle gain, 90 percent greater strength gain, 2.5 times the fat loss and 3.5 times the cardiovascular improvement, in 72 percent less training time. Every one is a ratio against the weight-training group, not an absolute change. Twice the muscle gain of a group that gained a little is a modest number; twice that of a group that gained a lot is a large one, and the absolute figures are not in our verified data.

The time figure deserves its own look. On the session lengths ARX describes, the ARX group trained 30 minutes a week and the weight-training group 135. A straight comparison comes out near 78 percent less time, not 72, so the 72 percent is measured on something the summary does not spell out. That is not a contradiction, it is a reminder that a summary is a summary, and the full paper is the document to read.

What the study shows

Give it its due. A commissioned study is still a study, and a journal publication is more than most fitness equipment can point to. On its own terms it supports a narrow, useful claim: that a short, infrequent protocol on adaptive resistance was reported to outperform a conventional program taking more than four times the weekly clock time, over 12 weeks, in the group measured, on the outcomes ARX quotes. If your question is whether 15 minutes twice a week on this equipment is a serious stimulus rather than a gimmick, the study is evidence in the direction of serious.

It also fits the design case. The motor loads the eccentric phase, the software records total force, max force in both directions, rep speed, range of motion, intensity, exercise time and fatigue, and a study showing the protocol produces measurable change is consistent with that machinery doing what ARX says it does.

What it does not show

Now the other side, and this is the reason the post exists.

• It is one study. Nothing in our verified record shows the 2021 trial repeated by another group, at another site, or with a different cohort.
• It was commissioned. ACE commissioned it, ARX cites it, and the figures in circulation are the ones ARX chose to publish. That does not make the work wrong; it means the framing you have seen is the brand's.
• It is 12 weeks. Long enough for early adaptation, not long enough to say what happens in year two, when a new stimulus is no longer new and the question becomes whether you still use the machine.
• It ran at one university. How many people took part, how trained they were, how the weight-training group's loads were set, and how outcomes were measured are not in our verified data. We are not saying those details are weak, only that we cannot show them to you; at $43,000, ask ARX for the full paper.
• It is a ratio. The multiples are against a comparison group whose absolute gains are not in our record.
• We have not replicated any of it. Lifespan Vault has not tested an Alpha or an Omni, and nothing on this page is our measurement.

The 2023 review and the XPRIZE arm

ARX cites two more pieces of evidence, and both need the same care. The first is a 2023 review in Sports Medicine that ARX references. What it covered, what it concluded, and whether it examined ARX equipment specifically or adaptive resistance in general are not in our verified data, so we list it as a citation the brand makes rather than a finding we can describe. The second is ARX's involvement in the XPRIZE Healthspan training arm, which has not reported results. An unreported arm is not evidence either way yet; when it reports, this post gets an update.

The remaining line on the ARX site, trusted by Tony Robbins, Dave Asprey and Ben Greenfield, is ARX's line, not ours, and it is an endorsement, not a study. Also worth writing down: ARX itself concedes that barbells win on cost and track record and teach you to balance and stabilize real loads. A brand that says that about its own $43,000 machine has earned a fair reading of its study.

The ARX Alpha: what the study does and does not tell you about it

The ARX Alpha is the smaller machine at $43,000, verified 2026-09-17: leg press, chest press, row, calf raise, torso flexion and torso extension on a guided sled that keeps every rep on one path, in 21 square feet at 655 pounds. ARX calls it its easiest machine to learn and names studios, in-season athletes and busy professionals as its buyers. The study tells you the method behind it produced the reported result in 12 weeks. It does not tell you that six guided movements are enough for your goals, because the study, as recorded, tested the method, not one exercise list against another.

Where it gives ground:

• Ten fewer exercises than the Omni, no belt squat, deadlift or Romanian deadlift, and no cable system, so none of the Omni's handles, attachments or grip variety.
• It still needs a dedicated 110V 20A or 220V 15A non-GFCI circuit and weighs 655 pounds, so the install is the same job as the Omni's.
• The $200 a month home software is required and identical on both machines, the license is non-transferable, and without an active license the machine will not run.

The ARX Omni: what the study does and does not tell you about it

The ARX Omni is the flagship at $46,000, verified 2026-09-17, $3,000 above the Alpha. The same motor and software drive a cable system with clip-on handles and attachments across sixteen exercises: belt squat, deadlift, Romanian deadlift, hamstring curl, calf raise, horizontal press, incline press, decline press, overhead press, pec fly, pulldown, pullover, row, high pull, biceps curl and triceps pressdown. ARX says it does the work of 10-plus machines in 37 square feet at 680 pounds, and names founders, clinics and home-gym owners replacing a room of equipment as its buyers. Again, the study supports the method, not the extra ten exercises; whether the Omni's library is worth $3,000 and 16 more square feet is a question about your training, not the trial.

Where it gives ground:

• It is the larger and heavier machine, 37 square feet against 21 and 680 pounds against 655.
• Same dedicated-circuit, non-GFCI requirement, same required software at $200 a month home or $400 commercial, same non-transferable license.
• The extra exercises come with a cable system to learn, and ARX itself calls the Alpha the easier machine.
• At $46,000 it is the most expensive single-purpose strength machine we cover, and ARX's own concession about barbells applies to it in full.

What it costs to run the experiment on yourself

Only training on the machine will settle the question for you, and here is what that costs over five years using only figures ARX publishes. Hardware is $43,000 for the Alpha and $46,000 for the Omni, verified 2026-09-17. Software is $200 a month for home use, $12,000 over 60 months, or $400 a month commercial, $24,000. Lifetime licenses exist per the site, but their price is not in our verified data, so the table uses the monthly rate; the electrician for the dedicated circuit is likewise not in our verified data, so it is listed and not priced. ARX quotes financing at about $1,200 a month through third-party lenders; that is a lender payment, not a price, so it is not in the table.

Two things fall out of that table. First, the study's headline is time, and time is the one thing the table cannot price for you: at 30 minutes a week against 135, the protocol as described saves about 91 hours a year, and what an hour is worth to you decides whether $105.77 a session is expensive. Second, twice a week versus once a week is the gap between $105.77 and $211.54 a session on the Alpha, and our catalog notes that most users train one to two times a week. The study assumes twice; your habit is the variable it cannot control.

If that makes you hesitate, good. Our Best Home Gym Equipment 2026 guide covers machines priced from $679.99 to $4,649, and the Amazon home-gym edit gets a strength, Zone 2 and recovery setup running for a fraction of one ARX machine. And if the 3.5 times cardiovascular figure is the one you want to check on yourself, a measured test before and after is the honest way; our VO2 max analyzer buyers guide covers analyzers from the VO2 Master Essentials Kit at $6,895, verified 2026-08-01, up.

Verdicts by buyer type

• The buyer who wants the shortest credible strength protocol and has the money: the ARX Alpha at $43,000. The study is the brand's evidence that 15 minutes twice a week is a serious stimulus, and the Alpha is the cheaper, easier machine to run it on.
• The buyer replacing a room of equipment or building a studio around one machine: the ARX Omni at $46,000, because the study is indifferent between the models and the sixteen-exercise library with belt squat and deadlift is what the extra $3,000 buys.
• The buyer who wants independent proof first: neither, yet. One commissioned 12-week study and an unreported XPRIZE arm are a reason to read the full paper and ask ARX for a session, not a reason to wire $43,000.
• The buyer who enjoys free weights and has the hours: a barbell, in ARX's own words. It wins on cost and track record, and the home gym guide starts at $679.99.
• The renter, or anyone without a dedicated non-GFCI circuit: neither machine, regardless of the study; ARX states its machines are not compatible with GFCI outlets.

Bottom line

The 2021 ACE-commissioned study is real, published, and the brand's, and all three facts matter equally. It shows that one 12-week protocol of about 15 minutes twice a week on adaptive resistance was reported to outgain 45 minutes three times a week of moderate-intensity weights, on the measures ARX quotes; it does not show that the result repeats, that it applies to you, or anything we have measured ourselves. Buy the ARX Alpha at $43,000 or the ARX Omni at $46,000, both verified 2026-09-17, for the time saving and the force data, with a five-year home cost of $55,000 to $58,000 in front of you, and treat the multiples as the reason to ask for the paper rather than the reason to sign. Read the Best Home Gym Equipment 2026 guide first if the numbers gave you pause, because that is what they should do.