How Aqua Knuckles Can Help Swimmers Move Faster Through The Water

Courtesy of Aqua Knuckles, a SwimSwam partner.

Aqua Knuckles help swimmers get faster by utilizing muscle memory for open finger swimming technique.

Why does open-finger swimming make you swim faster?

When swimmers pull through the water with their fingers slightly opened (about 5-10 mm apart), they push more water. Water does not escape through slightly spread fingers.  As the hands enter the water, they form a thin boundary layer. The water closest to the hand sticks to the hand to form this layer. The boundary layer is like a glove on the hand, adding more surface area to your hand. How thick the boundary layer is will depend on the speed of your hand through the water and the shape of your fingers. When you spread your fingers, water gets trapped between the spaces of your fingers because of this boundary layer. This effectively increases the surface area of your hand.

Golf balls have been taking advantage of the boundary layer for years to achieve

better distance and control. The dimples on a golf ball create a thinner boundary layer that stays closer to the ball’s surface.  This helps the air flow tighter to the surface of the golf ball creating less of a wake. The dimples on a golf ball reduce the drag by half. In swimming, we are trying to increase the drag from our hands.

Spreading the fingers gives the hands more surface area. Spreading your fingers is accomplishing the same effect as wearing paddles and is easier on your shoulders than paddles. You can’t wear paddles during a race, but you can spread your fingers during a race for a similar effect. The pull is a very important part of the stroke. The more powerful you can make your pull, the more powerful your stroke is. Wearing Aqua Knuckles offers the swimmer the ability to get very precise with his/her finger placement on one of the most important aspects of the propulsion of the stroke – the hand surface area. Using Aqua Knuckles really helps create a precise finger position which can be hard to accomplish otherwise. There are multiple scientific papers online and now some videos comparing open-finger swimming to closed-finger swimming. The papers all indicate that open-finger swimming is a better method of generating a more powerful pull by increasing your hand-surface area by as much as 10%. On a side note, we’ve also discovered that wearing Aqua Knuckles decreases stroke count.

Open finger swimming also increases the nerves exposed to the water by up to 35%. When you swim with closed fingers, the sides of your fingers are not getting exposed to the water. When a coach talks about “feel for the water”, this is how you can feel more. Having a better feel for the water helps swimmers make those micro adjustments to their pull, helping them swim faster. Some coaches believe the best swimmers’ edge is having a better feel for the water.

What are Aqua Knuckles?

Aqua Knuckles are training aids worn during swim practice for competitive swimmers and anyone who wants to move through the water faster (surfers use them, too). Aqua Knuckles are double silicone bands slipped over the ring and middle fingers of each hand. They are sold in pairs and follow ring finger sizing, though many swimmers prefer a snug fit.

Why should swimmers use Aqua Knuckles?

Training with Aqua Knuckles on a few sets during practice at least every other day makes swimmers faster when they race at meets. Our extensive testing with competitive swimmers indicates that swimmers can shave off as much as .5 seconds per 50 yards.

How did you come up with the idea for Aqua Knuckles?

I have studied swimming technique as both a competitive swimmer and a coach for decades. There are always ways to improve technique to get faster. Back in 2018, I was watching underwater Olympic racing footage of Nathan Adrian and noticed he swims with his fingers slightly spread apart. He swims like this all the way through his stroke (except for his streamline when diving into the water). I then started really paying attention to the finger spacing of the world’s elite swimmers and reviewed hours and hours of underwater footage. Many elite swimmers swim with their fingers slightly opened…using open-finger swimming technique – Katie Ledecky, Michael Phelps and Sarah Sjostrom, just to name a few. These swimmers’ hands are relaxed as they pull through the water. Their fingers are not tightly pressed together.

I felt like I made an exciting swimming technique “discovery” that, if widely known, would help a lot of swimmers get faster. Open-finger swimming technique is not something coaches teach or talk about. In fact, when most of us are learning to swim, the instructors tell us to tightly close our fingers. On my own, I started trying to swim with my fingers slightly opened and figured out it wasn’t that easy because I wasn’t used to swimming like that. It wasn’t intuitive for me after so many years of swimming with closed fingers. I decided I needed to make a device to teach myself open-finger swimming muscle memory. I tinkered in my garage for almost a year to create a simple but efficient design. I tried different materials, finger spacing, and shapes. With each iteration of the product, I’d go swim a bunch of sets to see how it felt. Finally, in the spring of 2019, I was satisfied with the Aqua Knuckles design. The final design is efficient, comfortable and minimalist with optimal finger spacing. It is also low profile and adds very little drag. My small team of innovators started doing time trials with competitive swimmers to test the final product. It was clear we were onto something that really helps swimmers get faster.

Can’t swimmers just spread their fingers on their own?

I tried this myself for a few weeks when I first figured out that many elite swimmers swim with their fingers slightly open. I just wasn’t successful at remembering to spread my fingers as I swam my sets, even for freestyle – let alone fly, back and breaststroke. I have been swimming with closed fingers for a long time. It’s hard to break old habits. I’m an open-minded swimmer with making stroke changes and even I was finding it very hard to spread my fingers without that muscle memory factor. Wearing Aqua Knuckles during practice sets can really help secure that needed open-finger swimming muscle memory across all of the strokes – and throughout the entire pull cycle of the stroke. Even if you have your fingers slightly spread at the catch phase of your stroke, many swimmers tend to close their fingers during the ending phase. If you’re wearing Aqua Knuckles during training, it forces your fingers to stay in the right open-finger position for the entire pull cycle.

What kind of swimmers should use Aqua Knuckles?

Aqua Knuckles are great for swimmers at all stages. If someone is looking for every possible way to take off time, this is a great tool to try because open-finger swimming might help shave off up to .5 per 50 yards. Young swimmers just starting out can wear Aqua Knuckles to learn this optimal finger spacing technique from the start. Coaches will have a certain relief using Aqua Knuckles with young swimmers because wearing Aqua Knuckles ensures the right finger spacing without the coaches having to constantly remind their swimmers what to do. Surfers can use Aqua Knuckles to make their paddling more powerful also.

Have you gotten any traction selling Aqua Knuckles?

Yes, we have. We are selling Aqua Knuckles worldwide. Team sales are popular, but many individual swimmers are buying Aqua Knuckles, too. In the United States, where Aqua Knuckles are made, swimmers all over the country are utilizing our product. Aqua Knuckles have been adopted by many NCAA college swim teams, as college coaches are always looking for ways to get their swimmers faster. Masters swimmers also seem to really like Aqua Knuckles, as they are usually open to innovation and looking for ways to improve. The swimmers and teams most interested in Aqua Knuckles are the ones very “dialed into” technique and how small changes can make big differences. It can be hard for coaches to try new things. New ideas take time to get widely adopted. We’ve been most successful with the teams, coaches and swimmers open to innovations in the sport and new ideas.

Where can I buy Aqua Knuckles?

Aqua Knuckles can be purchased directly at our website:

We are also distributed in the U.K. through our partnership with Allens of Kingsbury. We are so pleased to be partnered with this great swim shop. They are located just outside of Birmingham. Allens Swimwear offers free shipping to all U.K. residents. If you live in the U.K., you can find Aqua Knuckles via Allens Swimwear here.

Where and how do you manufacture Aqua Knuckles?

We make them here in California using a combination of 3d printers, silicone molds and hand finishing.

How did you come up with the name?

It’s just a riff on “Brass Knuckles”. I was thinking about calling them “Practice Bling” but decided Aqua Knuckles is more appropriate.

Use Code SWIMSWAM15 to get 15% off your next purchase.


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John O’Grady – Founder, Aqua Knuckles

John has been a competitive swimmer for nearly 40 years and is a real student of the sport. His love of the water has seen him through age-group swimming, high school teams, Divisions I and II college teams and masters swimming. He has competed in open water competitions in the Atlantic Ocean and has practiced in the English Channel. It is hard to find this guy out of the water! Currently raising his large family of competitive swimmers in Southern California, John is a swim coach at a local high school. When he is not in the water or on a pool deck, John runs a boutique media services company focused on creative projects of all kinds for both large and small entities. He enjoys cooking, surfing, travel, photography and spending time with his wife and children.

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