Originally Posted by John@NewPaltz
Little comment on the oxygen topic: Very interesting and I haven't spent enough thoughts on it, yet. Sun Yang started breathing on both sides (i.e. on every stroke) before the turns which definitely shows that oxygen demand is an issue when reducing SPM. If you're currently comfortably breathing every 3 strokes, you're still having headroom and could play with reducing SPM but breathing more often. In my personal case, I swam my fastest 2.4 miles with a 2-3-2-3 breathing pattern. But, if you're already at a 2-stroke breathing pattern, you might already hit a completely different (minimum) SPM boundary. Interesting....
Your objections have less to do with the two-dimensional aspect of spl x TT analysis (which after all is just various subtle variations on arriving at the same time to complete a given distance) nor with reducing SPL alone per se
. Remember, in my definition of "sweet spot" I included the condition "for that distance" -- i.e. you have specified sprint, long distance or whatever, and I stand by that.
O2 demand is very high not because Sun Yang is reducing stroke count. It is high because he is doing 1500m at world record pace. If anything, lowering his stroke count, if he has practiced it enough and played around with the spl x Stroke time interval equation enough to arrive at an appropriate sweet spot, should lower
his O2 requirements at his given record pace.
Of course you would be correct that, below that "sweet spot", lowering the SPL would indeed slow your best time, likely because of poorer efficiency and higher O2 demand. But that is only at your current degree of practice and training. Who knows what the future might bring?