Swimrun Paddles -
The Scientific Evidence

Updated January 2025

Swimrun Paddles are important items for most swimrun events. Having said that, I used webbed neoprene gloves for my first event as I was not confident enough to use hand paddles in a race. But after that, I did some research, and changed over to some green Speedo paddles with a bigger surface area.

"BUT WHERE'S THE SCIENCE?" I hear you ask. "WHAT IS THE RESEARCH EVIDENCE BEHIND SWIM PADDLES?"

To be honest, there hasn't been a lot of reliable scientific research into the optimal size and shape of swimrun paddles. BUT there has been enough research to help you to make an informed choice about the best paddles!

There are FOUR things to look at; The surface area of the paddle, the curvature of the paddle, the outline of the paddle in plan view (ie looking down from above), and whether the paddle has any holes in the body in addition to the strap-retaining holes.

Two Swimrun competitors swimming together at Ötillö Engadin in Switzerland, wearing green tops and caps.

Neoprene webbed gloves - not as crazy as might first appear - Even a small increase in surface area is effective!

Why use swimrun paddles?

SURFACE AREA.

A paper (1) published in the Journal of Strength and Conditioning Research investigated how hand paddle surface area affects the metabolic cost of transport (COT), arm cadence, distance per stroke, Vo2 and Heart Rate, while swimming.

Metabolic cost of transport (COT) is defined as the energy required to move 1 kg of body mass 1 meter in both swimming and running.

The use of hand paddles decreased COT, cadence, Vo2, and HR, and increased distance per stroke - all good! In this study, 5 sizes of hand paddles were tested; 201cm2, 256cm2, 310cm2, 358cm2, and 391cm2.

Interestingly, as paddle size increased, so did the benefits - BUT only up to a point.

The study concluded that; "The magnitude of the change of COT decreased as paddle size increased, indicating diminishing marginal return with increasing paddle surface area.

The largest-sized paddles actually increased COT per stroke (BAD) compared to swimming without paddles (p = 0.001). Therefore, results from this study suggest that an optimal hand paddle size exists (210–358 cm2) for proficient, adult swimmers, which reduces COT without increasing COT per stroke."

In other words, when it comes to paddle size, there is a Law of Diminishing Returns; Simply going for paddles with a large surface area is counter-productive.

The OPTIMAL paddle size lies between 210 cm2 and 350 cm2, depending on the hand size of the individual swimmer.

BASICALLY, YOU CAN FORGET ANY PADDLE WITH A SURFACE AREA OVER 350cm2 ! And if you are female or have smaller hands, the most efficient paddles will be more like 270 cm2. The optimal solution is to find a paddle that increases your natural hand surface area by about 70% - 100%.

An underwater photo of a swimrun competitor using hand paddles in shallow water.

Underwater shot of swimrun paddles in action!

SHAPE.

BUT there's more to it than just the surface area! What about the shape?

There are 2 ways to consider the shape:

The 3-dimensional shape. Is the paddle a flat board or does it have 3D curvature?
The shape in plan view (ie from above). Does it have a smooth outline like a ship's propeller, or does it have sharp corners?

Let's look at these features, and the science, one by one.

In 2022, Jessica Hargreaves published a paper titled "The effect of the curvature of a swimming paddle on the propulsion force." (2). She studied the relative fluid resistance forces generated by 4 different paddles of equal surface area, differing only in the curvature of the paddle. The curvatures were 0 degrees (ie flat), 10 degrees, 20 degrees and 30 degrees.

The results clearly showed an optimal angle of curvature of around 20 degrees. Increasing the curvature beyond 20 degrees resulted in lower fluid resistance force.

CONCLUSION; Flat paddles are NOT optimal for fluid resistance and therefore generating force.

SO, as well as forgetting about any swim paddles bigger than 350 cm2, you can also forget about FLAT paddles!

OUTLINE SHAPE (PLAN VIEW).

You may have noticed that ship's propellers have rounded edges and outlines, without sharp edges or corners. The reason for this is that sharp edges or corners can induce tip vortex cavitation, where the forces generated at the sharp edge cause the formation of vapour-filled cavities (bubbles). Once cavities form, there is a loss of force on the surface. This means less propulsion!

SO, the optimal outline shape for a swim paddle is smooth and rounded, NOT sharp corners with straight edges. Take a look at my green Speedo paddles, below.

HOLES IN THE PADDLES:

What's the scientific evidence for holes v. no holes? It is actually better to have a number of small holes in the surface of the paddle, because this induces a degree of turbulence which increases the hydrodynamic force generated by the paddle! (3) - (Experiments in Fluids 2021).

IN SUMMARY, the optimal paddles should:

increase your natural hand surface area by around 70% - 100%, which for most people will be 270 cm2 to 350 cm2;
the paddles should have a 3D curvature of around 20 degrees;
they should have a smooth, rounded outline when viewed from above;
and they should have a number of small holes to increase the hydrodynamic force generated by the paddles.

WHEN LOOKING AT SWIMRUN PADDLES, REMEMBER THESE FOUR IMPORTANT FEATURES.

Swimrun Paddles - Running

Remember, you have to carry the paddles while you are running. In all swimrun events, you have to cross the finish line with ALL the equipment that you started with. So you can't throw the paddles away mid-race if you get fed up with them!

There are 3 ways of running with your paddles;

If your paddles have a wrist strap, you can take your paddles off your fingers and flip them around against the backs of your hands while running.
You can take your paddles off entirely, and stuff them down the front of your wetsuit, after unzipping the front of your suit a little.
Some swimrunners take their paddles off and loop them through their swimrun belt, usually at the back. The disadvantage here is that the paddles can flap around while you are running!

Some paddle manufacturers like to promote the light weight of their paddles. However, in reality, we are talking 100 grams to 300 grams. This is miniscule compared to the weight of just about every other piece of swimrun gear!

Just think of the weight of water in your swimrun shoes or wetsuit after a swim. Most water should drain out pretty quickly, but a significant weight of water will remain. This puts the relative weight of swim paddles into perspective - there are plenty of other areas where you can save weight!

But, what do the most efficient paddles look like? Here are some photos of my current paddles, from Speedo. I like them because they are the correct size for my hands, they have a smooth curved outline, and they have a curved 3D profile!

These have been superseded by the Speedo Nemesis Contour, which look almost exactly the same! (JUMP down to see these paddles).

Two green swimrun paddles lying on a black surface.

SwimRun Paddles on my kitchen top

Two green SwimRun Paddles lying on a black surface, with a man's hand in the straps of the left one.

SwimRun Paddle on my left hand

Side view of a man's hand in the straps of a green swimrun paddle

SwimRun Paddle on my left hand

I replaced the black rubber straps with softer rubber tubing, in a different layout. You can see what I've done in the photos below. The new layout and softer rubber tubing allows me to turn the paddles round quickly when exiting the water, allowing me to use my hands without the paddles falling off.

A green Swimrun paddle with yellow rubber straps

The new rubber tubing straps

A green swimrun paddle with a man's hand inside the yellow rubber straps.

How it works!

A man's hand with a green swimrun paddle flipped around so that only one strap loops around his wrist.

Paddles turned around to allow hand use.

You can find a good deal on these Speedo Swimrun paddles HERE on Amazon.

Swimrun Paddles

And here are some photos of the swimrun paddles that Mogsy is now using. They are a bit smaller than mine, and they are flat (bad), but they are the correct size for her hand!

Mogsy's swimrun paddle

Side view of a black Swimrun paddle for ladies

Mogsy's swimrun paddle - right hand

A woman's hand inside the straps of a black swimrun paddle for ladies

Mogsy's swimrun paddle

GETTING BACK TO THE "WHY" - how much faster can you go?

Research shows that you can swim faster by about one minute per 1000 meters. AT LEAST. So if you have an event with several swims adding up to 5 kilometers or more, that's a 5 minute difference! MINIMUM! So definitely worth swimming with paddles.

However, you get the maximum benefit from paddles if you can maintain your normal 'without-paddles' cadence, or close to it. If your cadence drops significantly because your paddles are too big, you lose any speed benefit.

Here's my tip; it's more effort to swim with paddles, so you MUST train for it. During your pool sessions (which should be based around speedwork/repetitions), you should wear the paddles for at least 75% of the session.

And in your open water swim sessions, be it lake or sea, you should wear your paddles for the entire swim. It MUST become second nature to swim with paddles!

A green Swimrun paddle with yellow rubber straps and cut-off times written on the inside with black ink.

Cut-off times for the Isles of Scilly event

A handy trick for longer events is to write the cut-off times for each timing station inside your paddle - assuming you don't have black paddles!

Here are a couple of links to paddles available on Amazon that have been recommended by our readers:

Arena Vortex Evolution Hand Paddles

Arena Vortex Swim Training Paddles

The Arena Vortex Evolution is a smoothly-rounded design that will minimize any tip vortex cavitation issues. It is also available in a reasonable size (M) at approximately 320 cm2.

There are some holes in the body of the blade, but not many. However, these paddles are lightly curved, around 10 degrees, which is better than a completely flat design but not as efficient as a blade with a 20 degree curve.

They come in an obvious left-hand and right-hand design.

Arena Vortex Evolution Swim Training Hand Paddle - CLICK HERE for the best price on Amazon.

Speedo Power Plus Paddle

Speedo Power Plus Paddles

The Speedo Power Plus paddles have several features supported by the science.

They are available in a reasonable size (only the Small; the Medium, Large and Extra-Large are way over the optimal 270 - 350 cm2).
They have a smooth, rounded contour in plan view;
and they have many holes in the body of the paddle, which generate turbulence and therefore more force.

However, they are FLAT, which has been shown to be sub-optimal. Still, they are popular with many swimrunners.

Speedo Power Plus Paddle - CLICK HERE for the best price on Amazon.

Speedo Nemesis Contour

The Speedo Nemesis Contour has a very similar outline to the Power Plus:

Smooth, rounded corners and edges.
It is also available in reasonable sizes below 350 cm2,
It has holes in the body.
In addition, it has a 20 degree curved blade, which research shows is more efficient than a flat blade.

This is a swim paddle that follows all the science!

Speedo Nemesis Contour before trimming the straps!

Speedo Nemesis Contour Paddle - Click here for the best price on Amazon.

ARK Sports Carbon Air Rocket

A recent paddle design is the ARK Sports Carbon Air Rocket. As the name suggests, these are made of carbon fibre, which means they are very stiff, very light (70 grams) and very thin (1mm).

What about the science behind the size and shape?

They are flat, not curved.
They are too big, at 465 cm2.
They have sharp corners and ruler-straight edges, instead of being gently curved.
And they don't have any holes apart from the ones intended for the silicone straps.

Did they get it all wrong?

ARK Carbon Air Rocket

Obviously, lightness is a desirable asset, but we are not sure about the stiffness. Conventional plastic / EVA foam paddles seem plenty stiff enough, and the downside of high stiffness (measured by Young's modulus) is that it tends to be more brittle, which can result in a crack or catastrophic failure if subjected to a trauma.

We are not convinced that carbon fibre is a good option for swimrun paddles. As well as being more brittle than conventional plastic, it is also more expensive. It is better suited to the aerospace and Formula 1 industries where light weight and high tensile strength are important.

The Air Rocket paddles are available direct from ARK Sports.

SO, swimrun paddles are important, but you have to choose your paddles wisely, and then train with them a LOT before your event!

If you are entering your FIRST swimrun event, DO NOT feel that you HAVE to use paddles, especially in a sprint event - say under 15km (9 miles total). The shorter the event, the less you NEED paddles, and the MORE you need to concentrate on your trail running!

References;

1. ENERGETICS OF SWIMMING WITH HAND PADDLES OF DIFFERENT SURFACE AREAS: GEORGE H. CROCKER (1), JOSEPH F. MOON (2), JEFF A. NESSLER (2), AND SEAN C. NEWCOMER (2). 1. School of Kinesiology & Nutritional Science, California State University, Los Angeles, California; and 2. Department of Kinesiology, California State University, San Marcos, California.

2. The effect of the curvature of a swimming paddle on the propulsion force. Jessica Hargreaves, Barker College, 2022.

3. Sidelnik and Young, 2006; Marinho, 2020; Vilas-Boas, 2015). Experiments In Fluids, 16 November 2021