NYC is a difficult place to build a gym. Commercial real estate costs are high, so a gym owners first instinct is to find a location that has a lower price per square foot. Unfortunately, the lower your $psf goes, the further you’ll be from population dense areas like train lines, which are the veins that carry the lifeblood (customers) to your gym’s doorstep. If a prospective NYC gym owner is determined enough, they might look for a location with a good balance of $psf and high street traffic. What they’ll often find is a mixed commercial and residential building, and with that comes vibration issues.

What are vibration issues, and how are they different from noise issues?

Noise issues are audible, they’re the music or car horns you hear at night that your wife thinks are your fault (hi Mollie). They’re usually high frequency and low amplitude, and travel primarily through the air.

Noise dampening is pretty straightforward. You can baffle areas via noise absorbing materials on the walls, plug air gaps that act like holes in a bucket of sound, and acoustically isolate spaces that create a lot of noise like a music studio (put a pin in this one). If you’re the victim of noise issues, you can always use ear plugs which can help at the final destination, greatly reducing the ability for the sound to shake your ear drum. Noise issues are considered pretty straightforward to solve, at least compared to vibration issues.

When things vibrate, the problem becomes a lot more complicated. Vibration is primarily transferred via solid objects, like a foundation or concrete pillars. High amplitude low frequency sound like bass can also vibrate walls and shake buildings, even though it’s initial transmitted through air.

If you’re the victim of vibration issues, your solutions are much more limited. It’s technically possible to put each foot of your bed on vibration dampening pads, but when you get into the physics of vibration you’ll learn it’s incredibly difficult to attenuate (reduce) vibration at the destination. By the time it gets there, there’s a mix of frequencies and resonances that make it nearly impossible to choose a vibration dampening material that covers the entire spectrum.

That’s why when you’re aiming to solve vibration issues, you go to the source.

Acoustic isolation

Imagine the music studio example from before. An NYC producer has a room in their basement where bands come in and make tons of noise, meant to be recorded by sensitive instruments. That means not only do they want to prevent his neighbors from hearing this music, they wants to make sure noise from outside the basement isn’t ruining the otherwise pristine beat. The only solution here is to isolate it acoustically from its entire environment. A full 6 surface (four walls, floor, and ceiling) sound proofing solution consisting of different foams, air gaps, acoustic isolators, the whole works.

If you’re a gym owner suffering from complaints from your neighbors about vibration, you might be panicking at the idea of wrapping your entire facility in foam. Fortunately, we can be a little more clever than that by going to the source, the deadlift.

Odds are, deadlifts are creating a majority of your problems. If your gym has olympic lifting as well, that’s undoubtedly also causing vibration issues. Instead of vibration proofing the whole gym, you can solve the problem at the deadlift platform and prevent it from ever leaving that small area to begin with. By doing so, you avoid all of the complicated resonance issues, band stops, etc.

That’s the good news. The bad news is this is quite a challenging problem. Typically acoustical engineers in NYC deal with high frequency vibration, which can be solved with materials that are rubber-like and very high in durability. Deadlift vibration at its core is incredibly high amplitude and low frequency noise. Think about amplitude as the height of a wave in the ocean, and frequency as the number of waves per minute. Most vibration is like a windy day at the beach, 5 or so waves a minute, maybe strong enough to push you over. Deadlifts are like a tsunami. Very infrequent and enough to topple buildings.

What you can do

Our latest 24 hour gym opened in April 2024, S&S Bushwick. It’s a second story location in a new construction residential building. We had experience with vibration proofing from our previous locations, so we had high confidence going in, but by week two that confidence was utterly shattered. We received an email with a picture of a letter inside the residential elevator, with a dozen furious residents complaining about vibration issues all hours of the night. We had built in the vibration proofing that we used at our previous locations, but it wasn’t up to this new challenge.

Our first course of action was swift, we went to all the usual suspects - dumbbell drops, deadlifts, olympic lifting, and made strict rules. No dropping dumbbells, crash pads only, and no dropping deadlifts. It barely helped. Luckily, through my Mechanical Engineering degree I took two semesters of courses literally called “Vibrations 1” and “Vibrations 2”. I knew the theory, and had some experience in the application. I went to work and started solving problems one by one.

Dumbbells are pretty simple. We luckily had rubber coated dumbbells which somewhat reduced the severity of the problem we had to solve. We had also already installed a two-layer solution, a special waffled rubber flooring on top of a regular 3/4” stall mat. That wasn’t enough, so after the elevator letter we installed a layer of carpet padding between the rubber and the concrete floor, and a product called a “Shock Mat” under each dumbbell bench. Problem solved.

Our shock absorbing flooring, below a special 6’x8’ shock absorbing mat. One at each bench.

Olympic lifting is a big challenge, but crash pads are a great solution. Olympic lifters are used to using crash pads, so we had a moderately good solution pretty quickly. We put up signs to ensure members used crash pads only, but it’s easy to miss a sign, and it’s also difficult to hit a crash pad on heavy lifts. That means a ton of disruption for our neighbors in the residential floors of the building if members aren’t super diligent, which isn’t a great experience for them either. Luckily in this area, we had already installed a raised wooden platform for the whole space. That gave us some wiggle room to cut flooring out on either side of the platform, and install some special material underneath.

You can see the crosslinked polyethylene wrestling mat in the subfloor next to the shop vac.

Crosslinked polyethylene is a solid material for vibration proofing. That’s why it’s used in wrestling mats, where vibration proofing means saving a kid from dislocating an elbow (fun fact, I was a high school wrestling ref and unfortunately witnessed this happen once. Wrestling mats aren’t perfect.) Wrestling mats are by far the cheapest way to source this material, but they still aren’t cheap. Since we’re using them ‘off-label’, and cutting them up for use in platforms, we don’t need new or even whole mats. If you google around, you’ll likely find a local wrestling mat sales rep with a ton of scrap material laying around. They’ll happily sell it to you for a discounted rate.

This allowed us to greatly reduce the vibration caused by a heavy failed lift, or by a new member who wasn’t aware of our rules. It’s not a perfect solution (more on this later), so we still require crash pads. But these are incredible to have beneath the floor as a backup solution.

The deadlift

Out of the big three, deadlift is by far the hardest vibration source to solve for in a gym. There aren’t many off the shelf platform solutions that work well - vibration proof deadlift platforms absurdly expensive. In fact there aren’t even many good do-it-yourself options. I can write a book about all of the research I did into deadlift platform vibration proofing, a New York Times best seller no doubt, but I’ll skip a lot of that and jump right to the solution.

The 'trick' to solving deadlift vibration is converting that low frequency impact into pure mechanical displacement. If you drop a deadlift bar with 225 lbs onto a concrete floor and measure the frequency response, you'll see a broad spectrum of high amplitude vibrations. If you drop it onto a stack of pillows 10 feet tall and measure the frequency response, you'll measure virtually no vibration. That's because the impact energy has been converted into pure mechanical displacement, with a frequency well below 1 Hz. The energy is dissipated before the system can complete a single oscillation, preventing any transfer of vibrational energy to the subfloor.

With that principle in mind, we can design a platform. We need a material that can stop a deadlift bar in its tracks, and we need to install that material where the weight hits the ground. A solid centered platform for a reliable surface under the foot, with soft cushioned sides.

A confounding requirement exists though, the material can’t be so squishy that the lifter starts at a deficit. So what is this miracle material? It actually belongs to a whole category called “dilatant” or “shear-thickening materials”. Typically foams, these products experience strain-rate softening - they soften as the rate of the applied force increases. In the world of foams, the property is referred to as viscoelasticity, and it’s the reason you’ve seen memory foam mattress commercials where a person jumps next to an egg sitting feet away, undisturbed.

There are more specialized materials within this category that better address our specific problem. Certain high density polyurethane formulations, thermoplastic polyurethanes, EVA foam, and some that are much more exotic (read: expensive), designed at the molecular level to “glassify” upon impact.

Within this subcategory (yes, we can go even deeper), we can start to rank different foams by a very important metric called the “compression-set”. That’s the ability of a material to return to its original thickness after being compressed - typically expressed as a percentage of the thickness lost after repeated exposure to compressive force. Some of the above materials, like EVA foam, are typically considered high performing for a gym environment, but the demands of a deadlift platform expose a compression-set of up to 40%. In fact we tried EVA foam in an early test platform and initially it worked well, but then failed within only a few deadlift sessions.

OK so EVA foam doesn’t work, and that doesn’t help you fix your deadlift platforms. So what does work? A high compression set, semi-viscoelastic, affordable polymer.

High density rebonded foam

Rebonded foam is just chunks of recycled polyurethane foam glued together in a giant hot hydraulic press. It comes in a bunch of different stiffnesses, typically for comfortable furniture that’s not super expensive and needs to resist high traffic.

Two different rebonded foams. 120 kg/m³ and 200 kg/m³.

There are stiffer/tougher foams, and there are cheaper foams, but rebonded foam is the king of tough and cheap. We’ve also talked about it a lot already. It’s what’s inside both crash pads and carpet padding. Rebonded foam is in every single solution we’ve talked about thus far. It’s also how I plan on improving our weightlifting platform subfloor (it’s better than the crosslinked polyethylene).

Here’s the catch. Two catches, actually.

Rebonded foam is terrible in sheer. Sheer is the kind of force things tear with, and rebonded foam loves to tear into pieces. You might be wondering why on earth anybody would tear apart their deadlift platform. They wouldn’t do it intentionally, but compressive force causes sheer stress at the deformation boundary. As the material deforms, the surface area stretches and grows, and the material slows tears itself apart. This is why crash pads are consumable gym equipment. The solution is a layering of materials, each with their own unique mechanical properties.

The durability formula - compressive layer, sheer layer, durability layer.

The formula is pretty simple. You need a foundational layer to absorb impact, in this case it’s about 3.5” of rebonded foam. This layer does the bulk of the vibration proofing work, significantly deforming on impact and converting that vibrational energy into mechanical displacement. On top of that, you need a material that can prevent sheer stress on the compressive layer. Something that is low friction on its surface and can withstand a beating. The top is a straight up durability layer. This is weight-facing, so it needs to be able to take direct impact from heavy weight. It also needs to distribute the load across a wide area, so the dense metal plates don’t act as a hot knife through the foam layers.

The middle layer, the sheer layer, was a real challenge. I’ve tested dozens of materials and landed on an incredibly cool foam made by a giant industrial plastics company that primarily sells it to companies who mold it into football padding. It’s unfortunately not available without a wholesale contract, but I’ve been able to sample it and it’s truly incredible stuff.

This material is wonderful. It feels unlike anything you’ve ever touched - a mixture of silk and memory foam. It’s incredibly tough, very difficult to tear. It also has an insane compression set below 5%, which means after repeated exposure to high intensity compression, the material only loses 5% of its thickness. In my testing so far, there’s zero noticeable thickness lost in a commercial setting over months of continued use.

The downside is it doesn’t have a commercial name, and if it did it wouldn’t do any good to share it. Not only can you not buy this material, you can’t sample it either. The only reason I could is because I have another company that makes gym equipment, RepOne Strength. It’s expensive, but not not too expensive for a thin 1/2” sheer layer in our deadlift platform. Something like $5/sqft. If it weren’t so pricey, this would be a great candidate for a combined compressive and sheer layer.

There’s still hope. I’ve been A/B testing this material alongside a low cost easy to source TPU foam you can find in inexpensive Amazon yoga mats. It’s not quite the same, but believe it or not it performs nearly as well as the Lebron of foams shown above. You can buy a few and cut them up as needed. They’ll need to be replaced more often than the Lebronyurethane, but it’ll still last a really long time.

For the top surface, good vulcanized stall mat works well. Nothing to write home about. Rep fitness will send you a few high quality mats for a reasonable price. In a perfect world, we’d have a single piece 2 foot wide 1” thick smooth vulcanized rubber tile, but that’s not something I can easily sample.

The second problem

Remember that pesky second problem I told you about? The highest density rebonded foam that can be sourced in the United States is the stuff pictured above on the left, under the Thompson Fatbells. 120 kg/m^3 density, enough to help a ton in a home gym, but it’ll still leave the bar sinking as it wears over time. The durability of rebonded foam goes up as the density goes up, and this stuff isn’t really built for weights. The foam pictured on the right is sourced from China. Again, exercise equipment is kind of my thing. They were able to ship me samples, but their MOQ is a literal half a shipping container. 30 cubic meters. If you’re in a pinch, you can source this foam from really high quality crash pads by simply unzipping the vinyl cover and removing it, but it’ll cost you. Make sure to ask the company what the density of the foam is before ordering, 200 kg/m^3 is the sweet spot.

120 kg/m³ on the left, 200 kg/m³ on the right.

A little explainer of what you see here. I designed the platforms such that the foam sides are made of three pieces, each 16” by 24” and 3.5” thick. The center piece eventually deteriorates first as it gets heaviest use, so I can swap it with a fresh piece that’s 1/3 the price without trashing the whole side of the platform.

Unfortunately they shipped us only four sample pieces, two per side instead of three, and they got the thickness wrong by about a half an inch, which is why you see a bit of a ramp as the platform transitions between foams. This should be solved shortly with a new batch of samples.

The latest incarnation, version… 20 plus.

This is where we’re at today in our deadlift platform journey. The latest foam came in, and it’s incredible stuff. Members have given great feedback, and it’s holding up really well to commercial use. I just may need some luck as I try to convince this supplier in China to send me a sample order of enough pieces for 5 deadlift platforms, and pay for about $1000 in DHL air freight. As a hedge against my potential failure in procuring a pretty ridiculous number of sample pieces, and as a way to share what I’ve learned throughout this process, I designed a version of a vibration proof platform that could be shipped in a box to home gyms, using a tow strap as a frame. If there’s enough interest, it could help us crowdsource the materials needed to make an affordable vibration proof deadlift platform. It allows deadlifts of 700 lbs or more without a significant deficit, and absolutely crushes vibration. All for 80% less than the cost of the leading vibration proof deadlift platform.

If you’re a gym owner, either commercial or home, and are facing vibration issues yourself, reach out to us. I’ve done my homework and we have a good solution, but it’s a shipping container away from helping other gym owners solve their problem. If there’s enough interest, we can take matters into our own hands and make these platforms a reality.

Vibration proofing a gym - why deadlifts are the hardest problem, by far.

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