Originally Posted by John@NewPaltz
However, in my particular case I was experiencing something different and I call it "perceived exertion":
I'm able to get from say 10 down to 8 strokes per lane at the same exact lap time, BUT swimming with 10 strokes is way less exhausting. Squeezing out those last 2 strokes takes so much more energy, that it feels like a net loss in efficiency. Has anybody had the same experience?
I know I'm late to this conversation, but I've had this exact same experience of increased perceived effort levels when I reduce my SPL. I've had the same discussion with Coach Stuart, who told me the same thing he told you: lower SPL (longer stroke) reduces effort.
Now, a lot of the best stuff I have learned on this forum comes direct from Coach Stuart, and I'm incredibly grateful for his generosity and insights. But his answer that lower SPL leads to lower exertion has not always been true in my experience--like you, it's been the other way around for me when I try to drop down to 12-13 SPL (25m) instead of 15-16 SPL, for example.
BUT--I think that's because when that happens, I have not REALLY been lowering my SPL the right way--core stability, balance, and relaxation. Or I have not developed the fitness to maintain core stability, balance, and relaxation (more a skill than fitness issue), and so get tired when really focusing on those things to lower SPL.
I have also experienced exactly what Coach Stuart predicted when in a challenging 30 x 50m set (:45/50m pace, :20 rest), I focused on maintaining SPL of 16 or less. I found myself able to do it. Halfway through the set I was hitting 15 SPL. Then 14. I never got tired, and completed the whole set easily, and at lower SPL than planned. So, done correctly, Coach Stuart is right--lower SPL = lower exertion.