This is the eighth in a series of articles designed to help you swim at your best at meets or just appreciate your swimming experience more.
Nearly 30 years ago in 1988 American backstroker David Berkoff revolutionised swimming by doing underwater butterfly kick on his back (for 30-35 metres off the start, and 15-20 metres off the turn) to break the world 100 metre backstroke record three times. He broke the record in the heats and finals at the US Olympic Trials and then again in the heats at the Olympic Games before being beaten in the final by another exponent of the underwater kick, Japanese swimmer Daichi Suzuki. FINA, citing safety reasons, quickly limited the underwater distance to 10 metres and then extended it to 15 metres in 1991. Butterfliers and freestylers soon began to take advantage of underwater kick, most notably Russian 100 butterfly world record holder and 1996 Olympic champion Denis Pankratov, before FINA similarly limited the underwater distance in these strokes to 15 metres.
Why do swimmers use underwater butterfly kick in these three strokes? When you enter the water on a dive or on a backstroke start, you are moving at significantly faster than swimming speed. The same applies, to a lesser extent, when pushing off the wall in a turn. Doing underwater butterfly kick in a streamlined position is, depending on the individual, the fastest way to move in water, for a short distance at least (almost universally faster than freestyle or backstroke kick). So doing underwater butterfly kick after starts and turns gives you the opportunity to maintain a speed faster than your swimming speed. How far you can go while moving faster than your swimming speed depends on a number of variables and I will return to this question shortly.
I do not intend here to go into great detail about the technical aspects of performing underwater butterfly kick, but suffice to say that in order to generate maximum speed, I believe it is helpful to see the kick as being a continuous undulating wave travelling from your chest down through your hips, knees and ankles, much like a wave along a ‘flicked’ rope. As you move from entering the water on a start or pushing off the wall, to surfacing and swimming, it seems to be advantageous to progressively reduce the amplitude of this wave, or height/depth of the kick, and correspondingly increase the frequency of the kick.
I amuse myself by asking groups of young swimmers: “How far should you do underwater kick for?” I get various answers (including “Don’t end a sentence with a preposition.”) suggesting a certain number of kicks, or distances up to 15 metres, when of course the correct answer is: “For as long as you can stay above swimming speed, up to 15 metres.” Being good imitators, younger swimmers are inclined to want to emulate what elite swimmers do and hence stay down for a considerable distance, even though they are not travelling at faster than swimming speed for all of that distance. Perhaps some Masters swimmers are inclined to do the same. If you have dropped to swimming speed then you should be on the surface and swimming!
How far you can stay above swimming speed obviously depends primarily on your underwater kicking ability. This depends on core, hip and leg strength; and flexibility/range of motion in lumbar spine, hips, knees and ankles. The distance you can remain above swimming speed naturally also depends on how far above swimming speed you are before you commence your underwater kick, which is greater on diving into the water (and to a lesser extent) on a backstroke start than it is on a turn. It is also greater on, say, the only turn in a short course 50 freestyle than on the final turn of a 400 individual medley, and will also vary slightly depending on your speed in each of the three relevant strokes. Oxygen needs are also a factor in how far you can or should go underwater.
Like any skill your underwater kick can be improved with practice. It follows from what I have said above that as well as practising the skill itself, it is of vital importance to get a feel for how long you can remain above swimming speed, being aware this may vary depending on the factors I have mentioned. You may like to convert this to a certain number of kicks, or just try and develop the ‘feel’ for that point when you drop to swimming speed. For many Masters swimmers the number of kicks you should do will be low (two to four?) depending on your age and all the other factors. If it is a skill you use, then, as with all technical aspects, I encourage you to try and develop it, including judging how long you can stay above swimming speed, on EVERY start/push-off and turn you do, not only in sets intended specifically to assist with underwater kick.
Kick underwater and swim for (your) life!