{"id":654391,"date":"2026-10-20T09:37:47","date_gmt":"2026-10-20T16:37:47","guid":{"rendered":"https:\/\/www.swimmingworldmagazine.com\/news\/?p=654391"},"modified":"2026-10-20T09:37:47","modified_gmt":"2026-10-20T16:37:47","slug":"what-happens-when-a-fin-adds-speed-without-changing-the-kick-inside-the-data-behind-the-finis-slipfin-pro","status":"publish","type":"post","link":"https:\/\/www.swimmingworldmagazine.com\/news\/what-happens-when-a-fin-adds-speed-without-changing-the-kick-inside-the-data-behind-the-finis-slipfin-pro\/","title":{"rendered":"What Happens When a Fin Adds Speed Without Changing the Kick? Inside the Data Behind the FINIS SlipFin Pro"},"content":{"rendered":"

What Happens When a Fin Adds Speed Without Changing the Kick?<\/h2>\n

Inside the Data Behind the FINIS SlipFin Pro<\/h3>\n

What Makes the FINIS SlipFin Pro Different?<\/b><\/p>\n

A closer look at what happens when a fin adds speed without changing the kick<\/span><\/p>\n

Coaches have used fins for decades for a simple reason: they work.<\/span><\/p>\n

They add propulsion, increase speed, and create training conditions that are difficult to reproduce without equipment. But every fin also changes the way a swimmer moves.<\/span><\/p>\n

More blade and resistance can slow the kick and change the rhythm being trained. That can be useful when the goal is strength or maximum propulsion. But what about the sets where the goal is speed without moving too far away from the swimmer\u2019s natural kick?<\/span><\/p>\n

That was one of the questions behind our latest SlipFin Pro testing.<\/span><\/p>\n

FINIS conducted a six-month comparative study involving high-performance swimmers across Junior National, Sectionals, and Futures levels, evaluating SlipFin Pro alongside barefoot swimming and more traditional fin styles.<\/span><\/p>\n

The results helped define where <\/span>SlipFin Pro<\/b><\/a> fits.<\/span><\/p>\n

\"Finis<\/a>

Courtesy: Finis<\/p><\/div>\n

The Number That Stood Out<\/b><\/p>\n

One of the clearest findings was the speed of the kicking movement.<\/span><\/p>\n

The study measured this as angular movement speed, expressed in degrees per second (\u00b0\/s). Put simply, the higher the number, the faster the kicking movement was occurring.<\/span><\/p>\n

Barefoot: 72.7\u00b0\/s<\/b>
\n<\/b>SlipFin Pro: 73.0\u00b0\/s<\/b>
\n<\/b>Railed + long-blade fins tested: ~37\u201338\u00b0\/s<\/b><\/p>\n

SlipFin Pro was within roughly 0.4% of the barefoot measurement, meaning the speed of the kicking movement remained almost unchanged when swimmers put the fin on.<\/span><\/p>\n

By comparison, the railed and long-blade fins tested reduced that movement speed to roughly half the barefoot rate.<\/span><\/p>\n

That distinction matters because the fin that creates the most propulsion is not necessarily the right fin for every set.<\/span><\/p>\n

A coach may want resistance. They may want maximum propulsion. But for race-pace, rhythm, and technique work, there is value in adding assistance without dramatically slowing the movement the swimmer ultimately needs to reproduce without equipment.<\/span><\/p>\n

That is the space SlipFin Pro was designed to occupy.<\/span><\/p>\n

Train with speed. Keep the movement.<\/span><\/p>\n

Interested in bringing SlipFin Pro into your program?<\/span><\/p>\n

Qualifying teams can receive 20% off SlipFin Pro and other training gear.<\/span><\/p>\n

[SHOP SLIPFIN PRO]<\/b> <\/a> [GET TEAM PRICING]<\/b><\/a><\/p>\n

\"Finish<\/a>

Courtesy: Finis<\/p><\/div>\n

More From Each Kick<\/b><\/p>\n

Keeping the kick close to barefoot tempo is only valuable if the fin is also helping the swimmer move faster.<\/span><\/p>\n

That is what the testing showed.<\/span><\/p>\n

Compared with barefoot swimming, SlipFin Pro produced <\/span>18.3% more distance per kick<\/b>, along with a calculated <\/span>11.7% increase in propulsion.<\/b><\/p>\n

In simple terms, <\/span>each kick moved the swimmer farther through the water, while the speed of the kicking movement remained almost unchanged from barefoot swimming.<\/b><\/p>\n

That combination is what makes the result interesting.<\/span><\/p>\n

SlipFin Pro is not simply adding propulsion. It is adding assistance <\/span>without requiring the swimmer to slow down the movement of the kick to get it.<\/b><\/p>\n

For swimmers and coaches focused on race rhythm and tempo, that creates a different training environment from a larger fin designed primarily around resistance or maximum blade-driven propulsion.<\/span><\/p>\n

Where a Traditional Power Fin Fits<\/b><\/p>\n

SlipFin Pro was also evaluated against the <\/span>FINIS Edge, a more traditional power-fin style training fin.<\/b><\/p>\n

The Edge produced greater short-distance propulsion, while SlipFin Pro maintained movement much closer to barefoot tempo.<\/span><\/p>\n

That comparison is useful because it reinforces something coaches already know:<\/span><\/p>\n

Different fins should do different jobs.<\/b><\/p>\n

There are times when resistance and greater propulsion are exactly what you want. A traditional power fin can be a great tool for that.<\/span><\/p>\n

SlipFin Pro is intended for a different purpose: adding speed while preserving more of the rhythm and movement the swimmer will eventually need when the fins come off.<\/span><\/p>\n

It is less about asking, <\/span>\u201cWhich fin is better?\u201d<\/span><\/i> and more about asking:<\/span><\/p>\n

\u201cWhat am I trying to train?\u201d<\/b><\/p>\n

\"Finis<\/a>

Courtesy: Finis<\/p><\/div>\n

Movement That Stays Consistent<\/b><\/p>\n

Another finding that stood out was repeatability.<\/span><\/p>\n

SlipFin Pro recorded:<\/span><\/p>\n

97.7% acceleration repeatability<\/b>
\n<\/b>97.0% overall movement repeatability<\/b><\/p>\n

For coaches, that consistency creates a more predictable environment for technical work.<\/span><\/p>\n

If the equipment behaves consistently, it becomes easier to watch the athlete. Timing, amplitude, ankle movement, and rhythm become easier to observe and reinforce. Those were among the practical coaching applications identified through the testing.<\/span><\/p>\n

It also creates a simple opportunity for transfer work:<\/span><\/p>\n

Use the fin to reinforce a movement. Take it off. Ask the swimmer to reproduce the same feeling barefoot.<\/b><\/p>\n

The research identified this assisted-to-unassisted approach as one potential application for SlipFin Pro in technique training.<\/span><\/p>\n

So Where Does SlipFin Pro Belong in Training?<\/b><\/p>\n

There is not one fin that should do everything.<\/span><\/p>\n

Some sets call for resistance.<\/span><\/p>\n

Some call for maximum propulsion.<\/span><\/p>\n

And some call for higher swimming speeds while keeping the kick and stroke mechanics as close as possible to normal swimming.<\/span><\/p>\n

That is where SlipFin Pro becomes interesting.<\/span><\/p>\n

Its lightweight, open-heel design gives swimmers a very different feel from a traditional full-foot fin, while the testing supports the central idea behind the product:<\/span><\/p>\n

Add propulsion without asking the swimmer to completely change the way they kick.<\/b><\/p>\n

The Numbers at a Glance<\/b><\/h3>\n