This is the 5th stroke for swimming now - it has totally changed the sport - short-course of course much more since you can do it 2x. Why are times so much faster now - underwater kick and suits - that is the answer without a doubt. It seems easy - we all learned butterfly kick at some point. So what is the secret ??
I am still in disbelief how I missed this ... I literally watched David Berkhoff in person at the 88 games in awe of him doing 30m+ underwater - he started this revolution. But to be fair - all of us can not transition things very quickly - why does it take 30+ years for somebody to do 5+ fast underwater kicks after every single turn in the 500Free and destroy records ??
The "catch" of becoming fast in the underwater kick is THE CATCH for the recovery portion !!! I tried improving this kick since mid 2000s - and like many people I worked to improve the down kick in all sorts of ways - but the recovery is the hidden gem - that is the key - that may change my way of swimming. I watched a very detailed underwater video of myself and I realized that my recovery for the underwater kick was like hitting the break pedal - it totally slowed me down and times were proof - my fav saying .. the clock never lies - I was 0.3s slower when doing 3-4 underwater kicks vs just freestyle and maybe one quick kick. So I saw the video and then it dawned on me -- I went in the water and realized I literally treated the recovery portion of butterfly kick with absolute zero catch or intend to move myself forward - I used it like a minibreaststroke.. it looked ok - but my mind and muscles and body did zero catch.
As soon as I tried to catch - my body told me that I never ever activated those muscles in general - and they are weak - hamstrings / glutes / lower back have always been my weak spot. I wasn't even able to start this process with butterfly kicks - I need to first learn to catch the water -- started by actually avoiding down kick just moving the feet slow forward and then catching the water with the bottom of my feet and toes - standing and floating and so on ... its been 3 weeks and again the clock never lies -- still learning this and just starting this project - my 25 underwater time is already 1.5 second faster than before and I wasn't even going at max level - there is another 1-2 seconds there easily. For me - that's a huge difference - and as I said - the clock NEVER lies ...