It Depends - The Paddle Edition

If you are new to swimming and swimrun you will experience the speed benefit of pull-paddle swimming. Contrary to what you might believe, a lot of that speed advantage involves reducing drag using a large swimrun pull buoy. So are big paddles the way to go for additional speed? Well, it depends!

Let’s look at the first principle of swim speed which is made up of the relationship between two factors:

Factor 1 - the distance you can move for each stroke known as Distance per Stroke (DPS).

Factor 2 - the number of strokes you can take in a time unit expressed as Strokes per Minute (SPM). 

DPS x SPM = Swim Speed

These two factors exist in a dynamic relationship. Increasing one may decrease the other and have a negative overall effect on swim speed. What the swimrunner needs to do, is optimize this relationship for:

1. Their swim skill level

2. Their fitness level

3. The impact of the swim time and run time component in their swimrun event.

So what does the research say? In ROD HAVRILUK, Ph.D. meta-analysis of The Effect Of Hand Paddles On Swimming the summary of his key findings were:

1. Paddle Size and Shape:

   • Paddles are often twice the size of a swimmer’s hand, increasing the surface area (and thus potential drag) significantly.

   • However, because paddles and hands have different shapes, the drag coefficient (Cd) varies. A hand’s drag coefficient can range from 0.6 to 2.4, while a paddle’s is about 1.3. This difference means that, although paddles increase the force, they also alter the way a swimmer’s hand moves through the water.

2. Impact on Strength:

   • Larger paddles should theoretically benefit strength conditioning due to more resistance. However, studies show that hand velocity usually decreases with paddles, meaning the expected strength gains are less than anticipated. Swimmers often don't move the paddles fast enough to get the full conditioning benefit.

   • The evidence suggests paddles may not be as effective for building swimming-specific strength as once thought.

3. Impact on Technique:

   • With paddles, the hand travels a shorter distance underwater compared to swimming without them. This shortened distance can negatively impact stroke efficiency and technique.

   • Despite this, paddles make hand movement more noticeable, which can help swimmers better control their strokes.

4. Impact on Swimming Speed:

   • Even though paddles reduce hand velocity and distance, swimmers often swim faster with paddles. This suggests that the increase in force might outweigh the negative effects on technique for many swimmers.

5. Shoulder Injury Concerns:

   • Research is mixed on whether paddles cause shoulder injuries. The real issue is poor technique, especially during the arm entry and catch set-up phase. Proper technique can help avoid injuries whether or not paddles are used.

Research shows that swimmers often have a slower hand velocity with paddles than without, and with only a small increase in hand force. For example, the graph in Fig. 1 shows that while wearing paddles, male swimmers decreased hand velocity and increased force less than two pounds (Tsunokawa, 2018).

FIG. 1 > This graph shows a significant decrease in hand velocity and a significant increase in hand force. Asterisks indicate significant differences.

More specifically, hand velocity decreased on both the pull and push phases for female swimmers using paddles, as shown in Fig. 2 (Gourgoulis, Aggeloussis, Vezos, Kasimatis, 2008). When paddles were worn, hand velocity decreased and hand force increased in both the pull and push phases.

FIG. 2 > This graph shows a significant decrease in hand velocity and a significant increase in hand force using paddles in both the pull and push phases. Asterisks indicate significant differences.

To put the science into context, we need to consider what the paddle does. It holds the water and creates a platform on which you can exert force thus levering your body past an almost stationary hand. 

It therefore is logical that when you have enough surface area and stiffness to hold the amount of force applied to it, there is no additional benefit to it being larger (or stiffer e.g. carbon). The better the swimmer the smaller the surface area and “hold” needs to be. 

So why do some swimmers swear by the effect of paddle size on swim velocity? The key reason is their swimming skill level.

Swimrunners with a limited swim background are likely to have very slow natural stroke rates. In essence, with or without paddles they have not yet built the necessary neuromuscular pathways, stroke mechanics, and balance to benefit from the Strokes-Per-Minute component of swim speed. Therefore if you are not utilizing this mechanism, the Distance-Per-Stroke benefits from large paddles will give a consummate increase in swim speed.

The screen grab below shows the stroke rates of some of the female competitors in the recent Paris Olympic 10k marathon swim.  As you can see, stroke rate is a considerable contribution to their swim speed. 

Janet Evans had a stroke rate of a crazy 100+, I believe topping out around 120 strokes per minute when she set the then 800m world record of 8:16:22 in 1989. Janet is 165cm so to compete with the larger wingspan competition she had to develop this capacity. This is something to be considered. Even if I had the technique and drag coefficient of my swim squad buddy Jesper Holmberg, I still would never swim as fast as him at the same Stroke Rate. His height and the resulting Distance per Stroke are on his side. If you are vertically challenged (everything is relative) then developing SPM is a key enabler for you to keep up with the albatrosses even with paddles.

Note: Sometimes stroke rate is given as a cycle (both arms) so be careful when comparing numbers.

One positive effect of paddles that should not be overlooked is that you make the movements of a hand more noticeable, a swimmer can control it better. For example, a swimmer can feel if a paddle moves backward a horizontal distance that is equal to the distance without a paddle. This can allow for better technique for swimmers still developing their skills. But I’d argue that in this case, larger isn’t better, as you get a more natural swim stroke and still get technique feedback from smaller paddles.

The effect of paddles on swim speed for an elite swimmer is not as significant as it is for recreational swimmers

Although swimmers usually move the hand more slowly and through a shorter distance with hand paddles than without, the research shows that elite swimmers usually swim slightly faster with paddles than without paddles (Fig. 3). In five studies (Gourgoulis, Aggeloussis, Vezos, Kasimatis, 2008; Tsunokawa, 2018; Gourgoulis 2006; Barbosa, 2013; Gourgoulis, Aggeloussis, Vezos, Antoniou, 2008), swimmers swam faster with paddles. In two studies (Lopez, 2012; Barbosa, 2020), swimmers had no significant difference in swimming velocity with and without paddles.

FIG. 3 > This graph shows the results from seven studies that compared swimming velocity with and without paddles. Asterisks indicate significant differences.

My Choice for Most Races

I currently use the Evolvent Karlskrona Edition. I chose their small size (still pretty big) to ensure that my fingertips are close to the leading edge of the paddle. This is important as it maintains the lever's natural length and reduces shoulder stress. I also like the paddle shape as I find the additional surface area higher up the wrist beneficial and the front cut away makes the start of the catch easy to engage.

What Evolvent says: “Lightly cupped paddle in carbon-fiber-twill and carbon-fiber-extreme. The cupping creates a more economical insertion and a stiffer paddle. Wings against the forearm for a more powerful and economical pull.”

Size Matters

If we look at the photograph below, imagine the catch set-up phase when the right arm goes from extended to the initial catch position in the picture. If the paddle is too large for the individual and/or the swimmer puts too much force in this movement, the front of the body is pushed up and creates drag. In addition, this downward force does not contribute to forward propulsion and is wasteful.

If you lack the technique and/or strength to handle the size of your paddles what is common to see during video analysis is that from this catch position where the majority of the propulsive force is generated, there is a subconscious movement of the paddle to angle outward (or inward) to reduce the force on the shoulder. These “power-farts” (as I call them) are a tell-tale sign that your paddles are too big.

The second and third points that I mentioned that needed to be optimized toward, were your fitness level and the impact of the swim time component of the swimrun event.

We are not doing pull-paddle swim races, we are doing swimrun races, we are therefore not purely optimizing for swim speed.

I have a quiver of different paddle sizes in my rotation, everything from size 0.5 Strokemakers to Tengblad Carbon Mega Plates, plus everything in between. Over a 400m distance, I can adapt my DPS and SPM to swim the distance equally fast. However, the aerobic fitness contribution to higher SPM swimming with the Strokemakers 0.5 is significantly higher than the low cadence muscular endurance of using the big dogs.

This needs to be taken into consideration not only for the average length of the swims at your event (will you be able to hold DPS for the full length of the swims) but also for the runs that follow them (how much energy are you using on the swims). I tend to end up with the happy compromise of my Evolvents.

I surprised myself the other week when I took my small ARK plastic blades on my local swimrun loop and set a PR on a 600m swim segment. Note that in this case, I was using the runs as recovery between hard swims. In swimrun races, for me, it is usually the other way around.

Another good example is World Champ Desirée Andersson at the EX Super Sprint, she crushed the swims and the competition with Strokemakers Size 1 in combination with a higher stroke rate. 

FYI Strokemakers have seven different sizes from very small to very large -  0, 0.5, 1, 2, 3, 4 and 5.

Some of my tips for paddle swimming:

• Use the front finger loop; this allows you to get to the catch position quicker without unnecessary strain on the shoulders

• See and feel a downward angle on the arm entry to avoid shoulder issues and to avoid creating drag during catch setup

• The sensation is slow to fast and easy to hard through the stroke cycle

• Try to feel the paddle push back as far as a hand would to maintain technique and distance, and keep a perpendicular angle of the paddle to the water surface (don’t power-fart)

• Be realistic about your ability to hold speed (your combination of DPS and SPM) - just because you are faster over 100m or 400m reps in the pool doesn’t mean you will be faster over 1000m towards the end of a long race

• Regardless of what you choose on race day, make sure you experiment with different paddle sizes to avoid mono-cadence swimming during training

• As your swimming develops your optimal paddle size may change, do not have a closed mind to “what works best”

• Consider the specifics of your race to determine which paddles to use, for example:

  • I’ve used smaller paddles for colder water races to generate heat on the swims

  • For a fast run course, I’ve used larger paddles to keep the average pulse lower

  • I’ve used smaller paddles to keep the cadence and power on when swimming into currents and waves on a point-to-point course

Context is everything. Train and race smart.