Deconstructing Fly-Dive Butterfly

The FISU Men’s 200m Butterfly video from a few weeks ago quickly make the rounds for a quite surprising reason. The 2nd place finisher from Japan, Yuya Yajima, basically swam a legal version of the Fly Dive drill. If you haven’t seen it, it’s best if you view it (here) before reading ahead. Yajima is in lane 2, second from the bottom in a black cap.

His stroke rate ranged from 36 (1st length) to 30-32 (next 3 lengths). The winner, Koptelov, ranged from 43 to 50, while most other swimmers in that race had stroke rates in the low 50s. Yajima is basically taking about 2 strokes for every 3 taken by the more traditional butterflyers, and he still only does 2 kicks for every pull. For those of you who are interested in these things, his distance per stroke is up around 3.3 m/stroke! It’s quite an astonishing swim.

Some may be surprised that this is actually not a new way of doing butterfly. A few people have been using this technique, but not many. Check out this video that quickly surfaced right after Yajima’s video (here).

As well, a version of this stroke with 3 kicks as a drill has existed for decades. I first learned it back in the 70s. There are at least 2 versions:

• 3-Kick Fly Slow in which the swimmer’s arms enter the water and the swimmer submerges, does one unhurried kick while keeping the hands out front, and then when ready, initiates the next stroke. This is a good drill for focusing on the initial pull phase.
• 3-Kick Fly Fast, which is just the above drill, but done with a great sense of urgency. Useful for teaching flyers who start their pull too soon to extend their hands and stretch the stroke out a bit. The transition back to regular 2-Kick fly is relatively easy.

Perhaps the thing that finally drew attention to this technique was how fast Yajima went. A 1:55 for 200 Fly LC is an excellent time at any level.

So what are the mechanics of this stroke, and how can it be this fast?

Stroke Mechanics

While the stroke looks completely different, mechanically it really isn’t all that different. At a basic level, the swimmer is more or less just introducing an underwater glide before the pull.

Specifically, the start of the stroke is basically the same. As the arms are recovering, the head drives into the water first, and then the arms enter. That’s all normal. But here’s where we see one of the first keys to the stroke.

KEY #1. At arm entry, butterflyers are to drive their hips up so that the butt just breaks the surface. This allows the swimmer to be driving their upper body down into the water as part of an undulating motion. Fly-dive butterfly requires a very strong hip hinge move to allow the swimmer to drive deeper into the water. If you look at Yajima’s hip hinge, you can see that he gets far more of his butt out of the water than others, and occasionally even part of his upper leg. This higher hip position allows him to drive his upper body deeper for his underwater phase.

Key #2. While underwater, the arms should be closer to a streamline position than normal before pulling. Normal butterfly doesn’t really benefit from starting the stroke with arms close together, and so most butterflyers position their hands roughly shoulder width apart and immediately pull. But fly-dive butterfly holds that pre-pull position for up to a second – Yajima held that position for 0.85 – 1.05 seconds – and so a more streamlined position is beneficial. (Top butterflyers either don’t delay the pull phase at all, or stretch it out for at most 0.2 seconds)

Key #3. The kick during arm entry happens as normal. But the second kick, which normally happens at the end of the pull, actually happens right before the pull. In fact, this second kick speeds up the swimmer right as the pull starts, which should provide a higher speed. I can tell from playing with this stroke in the water, that it feels more powerful to jump start the pull with a strong kick.

Once the pull is done, the recovery is pretty much normal.

How Can It Be Fast?

The two primary factors in swimming fast are propulsion and resistance. So the first thing to wrap your mind around is a tough one: propulsion. With roughly 2/3 the number of strokes as other swimmers, there is no conceivable way that each stroke is 50% more powerful than other swimmers. So the arms are providing much less propulsion. It is possible that the strong second kick leading immediately into the arm pull provides for more propulsion than a normal pull.

This can only mean that water resistance is significantly reduced.

Butterfly is largely a matter of brute force. There is no rotation, as in freestyle and backstroke, to minimize the frontal area exposed to water. For both butterfly and breaststroke, any reduction in water resistance is achieved through body undulation. The fact that undulation isn’t as effective as rotation can be seen in the fact that even the best in the world can die in the last length of the 200 fly and breast.

So how can fly-dive reduce water resistance?

The first two keys above are important. A strong hip hinge will allow the body to get underwater quickly and with speed. In essence, it allows for a cleaner undulation of the body. The closer arm position during this phase allows for less water resistance during that roughly 1 second of streamline. Ideally, little speed is lost, and far less energy is spent.

Which leads to a key point. Fly-Dive Butterfly isn’t actually fast. I haven’t found or heard of any examples of truly fast 50 or 100 butterfly swims with this technique. Yajima himself does a 54.0 for 100 fly: a decent time but not nearly as world-class as his 1:55 for 200 fly. The important point here is that this technique uses far less energy, allowing a well-trained swimmer to have more energy for the 2nd half of a 200.

I should also point out, that as fast as Yajima’s swim was, his technique could still improve. His arm entries were splashier than most of the other swimmers in the final, and those splashes leech away speed.

There is also one significant disadvantage with this technique. With less frequent strokes comes less frequent breaths. In my experimenting with this stroke these last two weeks, I can tell you that the breathing aspect makes this technique very hard to maintain over a lengthy swim.

Summary

This high-profile and world class swim by Yuya Yajima may excite some swimmers enough to give this technique a try. But I suspect that Yajima has been working at this for a long time, and that it’s not an easy technique to master. And I can also tell you from personal experience that developing the necessary lung power will take some time as well.