What is the fastest way to swim?
Do you know? It may not be what you originally thought.
I'm sure most people don't realize that the fastest way to move in the water is actually under it in a streamline doing dolphin kick. Streamline dolphin kick should be your most powerful weapon going for you in a race.
Why you ask?
Unlike flutter kick which can be fast, dolphin kick incorporates more of the body, rather than just the legs. In fact to demonstrate how powerful your underwater work should be, watch this race below of an amazing young swimmer getting DQ'd by dominating his race with underwater dolphin kick in the 50 back.
This isn't just a benefit to short sprints. I've seen swimmers go from being in last place going into a turn only to come out in front off of the turn just because they executed stronger underwater work than their competitors during long events too. In fact, if you've ever watched some of Michael Phelps swim his longer races, he's not always the first guy to the wall going into a turn especially on the first lag of a race, but then watch him explode off that wall with those powerful kicks thrusting him body lengths ahead of the competition. It's incredible to see. However, in the last Olympics I did notice that the margins in which Phelps was able to pull ahead have narrowed as other swimmers are now more aware of this hidden stroke.
How to improve your dolphin kick
The problem I see often is that a lot of swimmers get lazy when it comes to their underwater work. They think dolphin kick is no different than doing butterfly so it's too hard or their streamlines are weak (and that's putting it nicely). I've also heard swimmers say "well you never give us time to work on it in practice". I always hate excuses when it comes to sloppy underwater work. Swimmers have every single lap to work on their underwater kick, even if they are only doing 25s. There are no excuses. Pushing off the wall in a tight streamline while doing small powerful dolphin kicks should and can be done all the time. Each lap is an opportunity to build strength and train your body into getting better at it. As I've mentioned before muscle memory is an incredible thing. If you don't have to spend as much time in a race thinking about all the small technical components of your stroke, you have more time to think about race strategy.
Some swimmers will say that they have weak dolphin kicks so they would rather do flutter kick off the walls. My answer to that is then work on it. Use kick sets to work on your dolphin kick. Train with and without a board. Practice doing dolphin kicks on the surface of the pool on your back is one of the best ways to increase your efficiency. Build up the strength in your core and your hips while maintaining a proper streamline. Focus on your weaknesses in swimming and turn them into strengths.
Some swimmers kick very rigidly while attempting dolphin kick. If you are one of these types, then focus on keeping your feet moving. As soon as your feet hit that downward point while kicking on your back, begin moving them back up towards the surface of the water. Your kicks should always be fluid. You should feel the power moves from your hips down to your toes.
Sometimes inefficiencies in dolphin kick come from having too large a kick. A large kick isn't necessarily a bad thing. In fact, in some cases, this is a more powerful kick, but it also ends up taking up more energy without as much benefit to your overall speed. Practice being in control of each kick. Think about your core, legs and toes being like a whip. Control your movements so that you can create that snap or flick at the end of your kick with your toes driving into that next kick. This will increase the number of kicks you do per meter which is good. Watch Olympians use their kicks. They are small blurs of motion, whipping back and forth to help increase speed. By practicing off every wall, you'll start to discover the right rhythm to your kick that maximizes your power and your speed. This balance can be tricky.
One thing I want make extremely clear though is that I'm not recommending you practice the entire lap underwater. The risk of shallow water blackouts are too high for any swimmer to do this, especially younger ones. Make sure you continue to breath when you need to if you are working on a strong streamline kick on your front or come up for air if you are kicking on your back. As I mentioned above, doing streamline dolphin with a tight streamline on your back at the surface is just as good as doing it underwater for training purposes. Then in a meet you only are allowed 15 meters so that's ok too. The idea is you want to train your body to know how to powerfully and efficiently get you to that 15 meters before anyone else.
I strongly recommend that most of your practice be near the surface of the water or on your back during your training sessions.
As you can see, there's a reason why the governing bodies of swimming have limited the amount of underwater kick you can do in each stroke. If we didn't have those limits in place, there would be a lot more athletes competing underwater for the entire race. You can also see why dolphin kick slowly been included in every stroke of the IM in various ways. I'm reminded of a particular breaststroke race that I was in when I was a young swimmer. It was towards the end of a long three day meet and I was competing in the finals of the 100 breaststroke. During one of my turns, I made the mistake of including a small, but powerful, dolphin kick in my pullout. I remember noticing how much further I got off that turn than the rest of the field. All from one little movement. Of course at the time this was considered an illegal pullout so I was DQ'd but in my mind it was worth it. I've seen used every practice and every race to maximize my underwater work to help me reach my greatest swim potential. I believe this is can be true for you as well. Think about each turn, every push off and every kick set as an opportunity to improve your underwater work. Then show up to your next competition with five strokes to compete in instead of just four.
Good luck and I would love to know how you use this fifth stroke to your advantage.