Gym Grips vs Fat Gripz: Why They're Completely Different Tools

Here's the most common mistake people make when they first see a rubber grip in the gym. "Oh, Fat Gripz." It's an understandable assumption. Both are rubber, and both go between your hand and the bar. But they're built for opposite goals, and confusing them means using a tool that works against what you're training for.

Quick answer: Fat Gripz artificially thicken the bar, which makes holding it harder. That deliberately shifts work into your forearms and grip. PUMPZ dual-panel gym grips are designed to do the opposite job, improving the stability and quality of your hand-to-weight contact so more of the work can land on the muscle you're actually targeting. Fat Gripz train your grip. PUMPZ are built for everything else.

What Fat Gripz do

Fat Gripz are thick rubber sleeves that convert a 28mm bar to 50mm or more, and they exist to make gripping harder. A thicker handle reduces your mechanical advantage, forcing your forearm flexors to work overtime. That's the point. Fat Gripz started the thick grips category, the brand name has all but replaced the generic term, and as a grip and forearm training tool they've always been marketed as an arm builder.

The trade-off is built into the design. When your grip works harder, it becomes the limiting factor sooner. The thicker handle also changes your wrist position, which is why plenty of lifters find heavy work on a thickened bar uncomfortable through the wrists.

What the research actually shows

This isn't just theory. A study published in the Journal of Strength and Conditioning Research (Krings et al.) had trained lifters perform deadlifts, bent-over rows, upright rows, concentration curls and pull-ups with and without Fat Gripz attachments, measuring strength and muscle activation via EMG. The strength cost was enormous. Average 1RM deadlift dropped from 141.5kg to 83.3kg, bent-over row fell from 94.7kg to 66.2kg, and max pull-ups went from 11.1 reps to 3.4.

The activation data is the part most lifters never hear. Forearm activation went up, as advertised. But activation of the upper-arm muscles went down during deadlifts, bent-over rows and pull-ups. And on concentration curls, the exercise thick grips are most famously used for, EMG showed no significant increase in activation at all, just a lighter load. On the compound pulls tested, the study measured less arm stimulus with thick grips, not more. On curls, it measured no bonus.

An earlier study by Ratamess and colleagues found the same load problem. Lifters had to reduce weight on almost every exercise tested with thicker bars, and pulling movements were hit hardest.

Two honest caveats. These were acute studies measuring single sessions, not long-term muscle growth, and none of them tested PUMPZ. But they're the best available evidence on what a thickened handle does to a working set, and the direction is consistent. If the goal is forearm and grip overload, the research supports exactly that use. If the goal is bigger lats, traps or biceps, the acute data points the other way, with lighter loads and, on the compound pulls tested, less activation in the muscles you're there to train.

What PUMPZ do instead

PUMPZ dual-panel gym grips by LIFTLABZ are a newly invented tool, not another version of something already on the market. There is no other portable grip built for both pressing and pulling. Instead of adding grip demand, the lower-profile dual-panel design is engineered to improve the interface between hand and weight. It's built to distribute pressure across the palm, seat the handle more stably in your hand and support cleaner force transfer, so pressing feels stronger and pulling connects better.

The intended effect is the opposite of the thick-grip trade-off. Your hands and forearms stop being the noisy, limiting part of the lift, so you can direct effort and tension into the muscle the exercise is for. The trademarked design gives your hand a better platform, with multiple ways to position it per exercise, because everyone's hands are shaped and move differently. PUMPZ fit barbells, dumbbells, machines and cable attachments, reduce calluses, and the rubber carries a lifetime guarantee.

Gym grips vs Fat Gripz: side by side

Are Fat Gripz worth it?

For their actual purpose, yes, with caveats. If you specifically want bigger forearms or a stronger crushing grip, thick-bar work is a legitimate overload method, best kept to a few targeted exercises rather than your whole session. Where Fat Gripz are harder to justify is as a general training upgrade. Put them on your back or chest work and the acute research says you're capping your loads and, on the pulls tested, reducing activation in the muscles you're there to train.

Which should you buy?

Ask what your limiter is. If your forearms never get a stimulus and you want them to grow, Fat Gripz are the tool. If your hands and grip interfere too early, meaning you finish rows feeling your forearms more than your lats, benching hurts your palms, and curls turn into a grip battle, that's the problem PUMPZ was designed for. For most intermediate and advanced lifters chasing muscle, that's the everyday pick, with Fat Gripz as the occasional specialist.

Wondering how grips compare to the other classic accessory? Read gym grips vs lifting straps, or see the full landscape in the types of gym grips guide.

FAQ

Fat Gripz is a trademark of its respective owner. LIFTLABZ is not affiliated with Fat Gripz, and this comparison reflects published research and product information.

See how PUMPZ differ from Fat Gripz. A world-first dual-panel design built for the press and the pull, not forearm fatigue. Shop PUMPZ →