I recently read a research paper on swim training with paddles looking at the effects on speed and injury swimmingscience.net.

In summary, most people automatically lower cadence with paddles so that the net power production remains the same as without paddles. So in order to create more power/force you need to keep the cadence closer to normal swimming. Therefore the researchers recommend short intervals keeping the cadence high for force production. I’d also say it confirms my argument for small paddles on longer sets.

In terms of injury risk the researchers found no real correlation to injury (caveat – they were researching good swimmers) although they did point out that incorrect form at the entry/extension increases the risk as the shoulder muscles are weak at the extension of the stroke in front of the head and if you go in too flat and far forward this creates extra stress on the shoulder joint. To avoid injury good stroke mechanics are required (even without paddles). The swim stroke should be thought of as slow to fast… fingertip entry at wrist length, soft at the start, and hard at the finish.

This pretty much supports my beliefs… I use paddles mainly as an aid to feel the water and NOT for strength training (go to the gym!)… on short hard intervals I also use them to increase my proprioception of force production through the stroke. Using large paddles all the time merely enforces mono-speed swimming – which is to be avoided.

As the autumn swim term periodization is all about learning/unlearning and improving your technique and movement patterns… please don’t use paddles as an aid just to “keep up” – use (smaller) paddles to improve. 

Squad Swimmer: “Very interesting. But I still can’t get my head around why some people increase their speed big time with paddles on. Are those the ones who are not “most people” and therefore manage to keep the cadence up? Or are they “gym-strong”? Another question. What “speed” was the research about. Speed with or without paddles or both?”

They compared speed with and speed without. My take is that for people with less feel for the water (i.e. all of us who didn’t swim as kids!) paddles help the swimmer feel something they would not feel on their own. This translates to increasing the propelling efficiency, the stroke length, and thereby the swimming velocity. So in your example, I don’t think they are necessarily gym-strong or high cadence – they just swim better with paddles (although your two factors may contribute a little). Great swimmers gain less with paddles. The research showed that increased speed in the study group had more to do with improved mechanics rather than increased force.

Another thing I’d add is that even in far less technical movements like riding a bike, non-elite cyclists (particularly triathletes) may find they create more speed (power) at lower cadences…. but mechanistically the highest power can only be created at high cadence (force x acceleration = power). That’s why an hour track record holder has both a low gear (force) and a high cadence (acceleration) – not something most mortals can recreate. So paddle swimming even with lower cadences (larger paddles) can be a good compromise to create additional velocity in a race situation to offset the absence of the stroke mechanics and neuromuscular skill of great swimmers.

Remember also that drag is the #1 enemy of a swimmer… and drag increases exponentially with swim speed. Big % jumps can be expected for a slower swimmer using paddles. If you are already fast, the additional power required to make you faster is an exercise in diminishing returns. Another reason why faster swimmers gain less.