The SwimRun Float is also sometimes called a "pull buoy". It's used simply as a flotation device during the swimming sections of any SwimRun event. But why would you bother?
Anybody entering for a swimrun must be a good swimmer already, so why use something that looks like a safety aid? After all, it's not as big nor as visible as the proper safety floats that long-distance swimmers tow behind them, in order to be seen more easily. What's the advantage? AND what are the disadvantages?
Let’s look at the positive factors first;
1. You lose some buoyancy from your legs in a swim run wetsuit because you normally have the neoprene legs finishing above the knee. This is to allow more mobility around your knees when running. But it means that the rest of your body has neoprene buoyancy, but not your lower legs. There is a tendency for your legs to sink a little. So, a little extra buoyancy for your legs would help to even things out, and keep your legs higher in the water, reducing drag.
2. Swim run events are HARD WORK on your legs! If you have not run in a wetsuit before, you’ll have to take my word for this. Before I started Swim Run, I had run 6 marathons and completed 9 triathlons. I’m not a veteran nor an expert on endurance events, but I HAD done a few things before trying SwimRun.
SO it was a major shock to discover how running in a wetsuit (even with the top pulled down to my waist) becomes progressively harder and energy-sapping. It’s not due to the heat generated by running in a suit (I live in Spain, remember, and am well used to running in 30 degree C / 90 degree F temperatures.)
It’s more to do with the resistance and stiffness of the neoprene around your lower body and upper legs. For the first few run sections, everything seems OK. But then you reach a point where you start to feel the fatigue building. And then it seems to build relatively quickly. In a marathon road race, the fatigue builds on a more gradual scale; and everyone agrees that after mile 20 is the hardest part. But it’s a gradual build-up. In a Swim Run, the fatigue seems to escalate quite quickly.
That’s where the float (pull buoy) can help! By using a float during the swim sections, you can let your legs relax and allow them to recover from the previous run. And the cold water of the swim helps too. But it’s important to fully relax your legs, to get the maximum benefit.
The TYR unisex pull float is an example of one of these floats on the market - check out the latest deals for this float here.
The disadvantage is that you have to somehow carry your float from the start line all the way to the finish! Obviously, you’re not going to run with the float between your legs - you need to carry it in some way.
The most common method is to thread some thin elastic bungee cord through the float, to make a couple of loops that you can put your leg through. Then you can pull the float and elastic cord loops up your thigh as far as possible and THEN you can pull the float around so it’s on the OUTSIDE of your thigh for running, OR pull it round so it’s between your legs for swimming!
This works quite well, but it’s important to get the tension / size of the elastic loops correct - you want the loops to be tight enough to hold the float in place while swimming, but not TOO tight so that the loops become uncomfortable while running.
Other options are to simply run with the float in your hand; this works OK while running, but can become awkward when you get to a water stop or energy station.
OR you can attach your float to your running belt/marathon belt, at the back. You can tuck the float into the small of your back and tuck it under a loop of elastic cord or running/marathon belt, like in the photo below, taken at the Ötillö Hvar race in Croatia. I dislike this option as the float jiggles up and down as I’m running, which I find annoying. However Mogsy finds that having the float tucked inside the back of her running belt is fine - so it's obviously personal choice on that one!!
We believe that it IS important. We didn’t use floats for our first
SwimRun in Hvar, Croatia, and although we did quite well on the swim
legs without it, our legs suffered badly on the running sections. So we
tried using floats for our recent event in Switzerland; (We
committed the schoolboy error of not testing enough in training, and
Mogsy found the elastic loops uncomfortable for running, so I ended up
carrying her float for her!).
Our swimming sections went well, with us regularly passing other teams as we had done in Hvar, but the big improvement was in our running, where our legs seemed to last longer before the fatigue and exhaustion started to build. And this was at over 6000 feet altitude!
So the SwimRun floats definitely helped!
We have moved on to a "system" which involves a belt, incorporating a clip to hold the SwimRun float in position on your thigh while running. It also has D rings for clipping the tow rope.
The actual shape of the SwimRun float can vary quite a bit. Most competition events have a maximum size of flotation device in their rules - (after a team turned up at a race a few years ago with an inflatable "mobile phone" the size of an air mattress!) - but just about any commercially available pull buoy intended for use as a training device in a swimming pool will be fine.
Some competitors will try to get a more "aquadynamic" shape, to reduce resistance and drag in the water, by using an empty sealed plastic mineral water bottle, adapted for use with elastic cords.
Whether there is really IS much drag reduction is debatable; I haven't seen any laboratory testing to prove it. As with most things in SwimRun, you have to test it out for yourself! Good Luck!