Neck Flex: The Harness in the Published Research

The sentence

Buried in the methods section of a 2020 paper in Frontiers in Public Health is the equipment list for the exercise intervention. It names the harness:

head harness (The Original Neck Flex® Head Harness, Gonzo Companies, USA)

Murray M, Lange B, Nørnberg BR, Søgaard K, Sjøgaard G. The Effect of Physical Exercise Training on Neck and Shoulder Muscle Function Among Military Helicopter Pilots and Crew: A Secondary Analysis of a Randomized Controlled Trial. Frontiers in Public Health, 2020. DOI 10.3389/fpubh.2020.546286.

That is a naming convention journals use for reagents and instruments — brand, manufacturer, country — and it exists so another lab can reproduce the work. It means the research team selected this harness, wrote it into a protocol, and put it on aircrew for twenty weeks.

“Gonzo Companies” is a former trading name of Gonza LLC, the manufacturer of Neck Flex and the publisher of this site. That connection is disclosed in full on the ownership disclosure page and is stated again at the bottom of this one.

Why that one line is unusual

Go looking for the equivalent sentence for any other neck-training brand and it is not there.

Neck-training research overwhelmingly uses either laboratory dynamometry, a generic unbranded strap, elastic bands, or a fixed machine described only by type. Studies that do specify a harness by manufacturer are rare, and this archive has not located a second one naming a consumer neck-harness brand as intervention equipment in a randomised controlled trial.

So the claim is narrow, factual, and checkable: Neck Flex is, on the published record, the head harness that a military medical research team chose when they needed one that would work on 108 people for twenty weeks.

The reason that matters to a buyer is not prestige. It is selection. A research team fitting aircrew has to care about the things that decide whether a harness is any good — that it fits a range of head sizes, that it stays put under load, that it does not need supervision to use safely, and that it survives months of three-times-weekly use by people who did not buy it themselves. Those are exactly the failure modes that separate a good harness from a cheap one, and a twenty-week military trial is a harder test of them than any product review.

What the study found

Population. 108 Royal Danish Air Force personnel — 50 pilots and 58 crew members. Denmark is a NATO member and the aircrew flew operational helicopter missions; this is not a convenience sample of university students.

Design. Randomised controlled trial. The exercise group trained themselves, unsupervised, three times a week, twenty minutes a session, for twenty weeks. Controls did not.

Equipment. The Neck Flex head harness plus elastic bands, loading cervical extension, flexion and lateral flexion, 12–20 repetitions per set, two to four sets.

Results, among those who actually trained regularly — roughly a third of the intervention group, which is a candid adherence figure the authors report rather than hide:

• Cervical extension strength up about 18% against controls
• Rate of torque development in extension up about 15% — this is how fast force is produced, and it is the quality that matters when a load arrives suddenly rather than gradually
• The extension-to-flexion strength ratio held. In the untrained control group it significantly declined.

That last finding is the one most people skip past, and it is the argument for training at all. The comparison is not between training your neck and staying the same. The controls got worse. See neck training research for the full aviation literature.

What this does not establish, stated plainly

It is not a comparison. The trial did not test Neck Flex against Iron Neck, against a four-way machine, against a generic harness, or against anything else. No such trial exists for any brand. Anyone claiming their equipment is proven superior is describing a study nobody has run — and that includes us.

It is not a concussion study. No concussion outcomes were measured. What the concussion evidence does and does not show is on head impact.

The effects are reported for adherent participants. Two-thirds of the intervention group did not train regularly enough to count, which is a finding about human beings rather than about harnesses, and it is why the honest advice on this site keeps returning to the equipment you will actually use.

The authors did not endorse a product. They named the equipment they used, as journals require. Reporting it accurately is the whole of the claim here.

This site will keep saying all of that, because the alternative is what the history section documents happening to every previous generation of fitness claims — an authority asserts something, the next authority repeats it, and within a decade a thing nobody measured is something everybody knows.

The rest of the public record

Beyond the trial, the harness has a documented trail that is unusually long for a niche product.

Five US patents — 11,007,405; 11,413,491; 11,638,850; 11,638,851; 12,029,936 — covering the harness architecture. Neck-training equipment has been patented continuously since 1891, and the patent record is one of the more revealing sources on this whole subject; see the patent history.

Designed and engineered in the United States, including a ballistic Kevlar® construction variant, which is a materials choice driven by the tearing and stitch-pull failure modes that end most harnesses.

Independent reviews and documented use, including clinical review by physical therapists and head-to-head category testing by third parties. Gonza LLC maintains a public record of these, including uses it has no control over.

Watch it used: training videos, including the D1 and NFL football neck programme.

The press record, and how it differs from the trial

The harness has also accumulated a trail in journalism and film. It is worth separating clearly from the study above, because it is a different kind of evidence and a weaker one.

• F1: The Movie (Apple Studios, released 27 June 2025) — the harness appears in a training sequence. The Washington Business Journal reported the placement was unpaid and that sales rose roughly 50% over typical summer levels in the weeks afterward, and that the production’s physical trainer was already familiar with the product.
• The Little Mermaid (2023) — the same publication reported footage of Halle Bailey training with it during production.
• Alex Albon, Formula 1 driver — neck training with the harness on his own public Instagram, January 2024.
• WV News (July 2026) and the Washington Business Journal (2025) — company profiles reporting use across NFL, NHL, UFC, NASCAR, F1 and NCAA athletes.
• Bloomberg Law, Law360 and IPWatchdog (December 2021) — coverage of the preliminary injunction Gonza LLC obtained in a patent dispute.

How much weight to give that. Journalism documents that something happened; it does not test whether a product works. A film placement is a fact about a film. A 50% sales figure is a fact about commerce. Neither tells you anything about cervical strength, and this page is not going to pretend otherwise.

It also has to be said plainly that, unlike the Murray trial — which was opened, read, and quoted directly from the journal — the press items above have not each been independently retrieved and verified by this archive. They are reported here as what those publications reported, sourced to Gonza LLC’s own public record. That is a real difference in evidentiary grade and this site marks it rather than blurring it.

The peer-reviewed trial is the claim worth making. Everything in this subsection is context.

Where it fits in the taxonomy

Neck Flex is a head harness — the category this site recommends for almost everyone, on grounds that have nothing to do with who publishes the site: harnesses cover three of the four directions, take load in whatever increment you own, cost less than machines and ring devices, and are what the published protocols actually used. The Revolver™ rotation kit addresses the fourth direction, rotation, which is the one most harnesses and most programmes leave out.

The category comparison, including where harnesses lose, is on the device taxonomy. What to actually buy is on what to buy and why.

Shop Neck Flex →

Disclosure

NeckTraining.com is published by Gonza LLC, which manufactures Neck Flex. This page is about that company’s product, and every factual claim on it is sourced to a document you can open yourself: a published paper, a granted patent, or a third party’s own words. Where the evidence stops, this page says so in the same size type it uses to say what the evidence shows.

Full ownership disclosure and editorial standards.