Did the XOTrainer Arm Exerciser used to be known as by another name?

Yes, indeed. We've undergone a rebranding, which also reflects some recent product improvements.  We did not want any potential confusion with another company.

Is the XOTrainer Arm Exerciser a one-size-fits-all exerciser?

Human beings come in many sizes. XOTrainer arm exercisers fit about 85% of people. Our newest straps fit very large individuals comfortably, and well as average-sized folks. If you have small arms, it may not fit comfortably. If the problem is the narrowness of your arm, you can add material inside of the hinge area (some people like to put a sweat band around their elbow and the hinges sit against the band). If the splint under your armpit is too long, there is nothing that can really be done. If you have this problem, please return them for a refund and thanks for trying XOTrainer.

Are improved straps available for the XOTrainer Arm Exerciser?

Yes. Early on, all units shipped with a regular size strap. As time when on and we learned more about our product and market, we have added the improved straps for the wrist and upper arms free with every shipment. These straps are slightly longer and significantly wider, and are much improved over the original.  They fit average to larger people. These are now included with each unit we ship. If you purchased the XOTrainer early on (possibly under the name XOTrainer™ Fitness), and did not receive the improved straps, we are happy to send them to you at no charge. PLEASE USE THESE UPDATED STRAPS! Use our contact form to let us know what you need, and be sure to include your address.

OUCH!  What is hurting my arm?

Typically, the velcro is hurting your arm if it touches it..  The Neoprene strap should not, but you need to make sure that the velcro does not overlap the Neoprene, and scratch your skin.

How quickly will I receive my shipment?

Shipping time can vary throughout the United States. Shipments are processed the morning after we receive your order. You will receive a US Post Office confirmation and tracking number when we ship. In most cases, your XOTrainer Arm Exerciser will arrive in 2-3 days.  UPS shipping is also available during the weekdays.

Do you ship outside the U.S.?

We currently ship internationally. Overseas shipments require special handling so beware of the additional cost. 

X-strap? Over the forearm?

The video was made with the original prototype. We redesigned the new cross strap and eliminated the cover for the cross straps on the forearm as shown in the image video. The cross strap cover is no longer needed. Please note, we have noticed that many people will put their arm THROUGH the X-strap.  Actually the entire strap is designed to go over your forearm. Also, once you adjust it, you should not have to release it to take XOTrainer™ off. These suggestions will make sure that the X-strap works well and will not fail over time.

Do you have a customer service hotline?

Not at this time. We get so few calls or complaints it’s difficult for us to justify the expense of a person sitting all day long at a phone that rarely rings. If you have a question or need additional support, please send an email to support@xotrainer.com. We are able to answer and address most inquiries in less than 24 hours.

Can I use the XOTrainer when I’m boxing or fencing?

Definitely. Boxing and MMA is one of XOTrainer's target sports. During training, the arm exoskeleton strengthens the triceps and biceps (in that order). It increases speed and endurance. It should not be used during an actual match because the additional resistance will slow your action and throw you off. When bowling, the fine-tuning that you work so hard to perfect will be off because of the extra resistance to motion. When fencing, a 20-ounce sword could feel like it weighed 20 pounds. Your arm is going to be quivering by the time you are done.

What’s the best way to become acclimated to the XOTrainer?

You should probably start at a low resistance setting. It may seem easy, but given the number of repetitions during your work out, you’ll feel more fatigued than you bargained for. As you become stronger, you can increase resistance by tightening the knobs. You may also want to tighten the harness. That could be uncomfortable if you do not adjust the harness carefully, and certainly sweaty.

Is the XOTrainer washable?

Yes. Wash the straps by hand with a mild soap and cold water. Rinse and let them line dry. They’ll be good as new. We DO NOT recommend MACHINE WASH OR DRY THE STRAPS and METAL COMPONENTS (it will decrease the life of the straps, and the nylon may damage your washer). Use a damp  cloth to clean the exoskeleton (BE SURE TO WASH OFF ANY SOAP, AS THAT MAY IRRITATE YOUR SKIN).

How much muscle growth can I expect?

Results vary depending on the diligence of the tester.  If you sit at a desk all day, wear it for 5 days a week, and do no real exercise, you will still see an increase in the circumference of your bicep/triceps region by 1/4” per week. If you are a workout nut, and use it intensively, at the highest settings you can stand, you will see 1 1/2” per week increase in your upper arm circumference.  We have actual university studies planned, but do not have the results of these yet.  These findings are reported by our people who have been diligent enough to measure their results. Please review the test results (found on our news page) from the University of Oklahoma, School of Exercise Science.

Can the XOTrainer be used for physical rehabilitation?

We are not allowed to recommend using the XOTrainer for rehabilitation until we have FDA approval.  However, we do get a lot of mail about successful experiences.  We work with a national physical therapy clinic who uses the XOTrainer with their clients. They write: “Yes I do have experiences to share with patients and conditions for which the product is beneficial.”  We have completed clinical trials, which took (about 3 years), and you may read the results on our news page.

Is there a military discount for purchasing XOTrainer?

Yes we do offer a military discount. We have a huge military following, and apparently we are being recommended by boot camp sergeants to strengthen the recruits. If you are active in any of the armed services or a veteran, you may use the code “XOT10” at checkout, and that will give you a $10 discount on your order!

What are the materials used in the XOTrainer units?

The arm splints are amazingly strong lightweight nylon infused with fiberglass, stronger than steel per ounce. The washers are made of synthetic buna rubber which has the highest coefficient of resistance while remaining durable and compressible. The hinges are nylon over nickel. The harness is made of Non-Allergenic Neoprene, with Velcro fasteners.


We have had many people write to us with astounding results.  We have noticed that if you are younger, your results will be more significant (probably because the body is in the building mode); from toning to actually building muscle. 

There are several excellent reviews on YouTube now, which were done without our involvement:



We should tell you that you should note the X-strap comments above, since the X-strap is designed to be completely over the forearm.

If you would write us and send us some photos or videos, we would love to post you on our Facebook page, and we will send you our new T-shirt.  Tell us your size!

Do you have any future plans for other fitness devices?

Glad so many of you have asked!  Yes. We have designed a Knee Exerciser and have 3 working prototypes which are being tested and refined, and we expect to launch the product ... (still counting). We have completed designs for shoulder, hip, and back units which are in development. These will not be available for at least a year. Our goal is that XOTrainer will eventually offer an entire body exoskeleton exercising machine, and our new branding reflects that goal. Humans come is an amazing variety of sizes and shapes, so there is a considerable amount of experimentation and research required. We have learned a lot over the last 10 years, and future products should be able to be developed more rapidly as a result.


XOTrainer is slipping out of position.

The elastic cord on the back just above the elbow is called the stabilizer.  Its main purpose is to make sure that the XOTrainer stays in the right position on your arm.  If you are doing intense workouts, or noticing that the XOTrainer is slipping off your arm, then tighten this cord (not enough that you can feel it), and it should solve this problem. To tighten the cord, pull to the desired tension, then slip the cord into the keyway, which should lock it into place.

XOTrainer is uncomfortable, and scratching my arm.

This is caused when the Velcro is allowed to touch the skin.  The neoprene is a special synthetic material that is made to be in continuous contact with human skin, but Velcro is NOT.  Make sure that the Velcro is fastened in the center of the strap.  If you are not using the latest straps, change to these, as the width of the Velcro gives more margin on the sides to help your skin avoid the Velcro.  In a few cases, some people will not be able to stand even the neoprene on their skin, and in that case, please return XOTrainer™ for a refund.

XOTrainer is too tight for my forearm to fit through the harness.

The x-strap is one piece, fits entirely OVER your forearm.  This is the piece with the LOGO on it, and you should be able to see the logo on top of your arm once it is on.

The Exoskeleton seem to want to move out of synch.

This is caused when the tightness of the hinges are uneven.  You can feel the tightness of the hinges with your fingers (or wrench, if you use one).  It is important to balance the resistance between the 4 resistance hinges as much as possible.  If the splints move easier on one side than the other, tighten that side more. Side note: some people have asked why there is not markings on the knobs to read the resistance setting.  We originally had those, but with time, the washers will wear, and the reading is off.  So we elected to remove the markings as it is pretty easy to feel the resistance.

The splints jam into my armpit.

Return the XOTrainer for a refund. One of the biggest challenges of XOTrainer design was to make the exoskeleton fit as many human shapes as possible.  Unfortunately, we could not adapt to the folks with a short upper arm.

My straps broke.

Let us know, send us an email with your order number and/or your address.  Tell us which straps failed and we will send you the latest versions for replacements.

The donut-elbow-harness fits better and works better above my elbow.

Yes, many people like this position better, and it works better for their arm size.  It does not affect the effectiveness of XOTrainer, so feel free to find the best position for your comfort.

Can we add XOTrainer products to our web site?

Yes. We work with many different sites, such as dudeiwantthat.com, and appreciate their customer referrals.

What happened to Armore Fitness?

A company called Under Armour decided that we were infringing on their name use, and rather that fighting them in court, we decided (eventually) to change our name to XOTrainer.  Many tell us that our new name better explains what we do, but we had to retool, and this has caused delay and costs.


All items returned or exchanged must be accompanied by an explanation of the problem, order number, and your name and address. Sorry, we do not have the budget for return shipping.
Please ship to XOTrainer:
16065 Brier Creek Drive
Delray Beach, FL 33446
If you have a question or need additional support or if you discover a problem after you've accepted delivery, please contact us at  support@xotrainer.com. We may be able to resolve the problem without requiring you to return the item. Please retain all packaging material until you're completely satisfied with the condition and performance of your purchase. Doing so will make it easier to return the item if necessary.
Note: Prices subject to change without notice.