Yesterday, after work I swam for half an hour and was very pleased with the process if not the pacing. I worked with the TempoTrainer and did the warm up at 60SPM which ended up being slightly slower than usual at around 5 minutes. Then I upped the cadence to 62SPM for 400m of RHS only strokes which felt fairly hard going and came in at 9:42min which is OK.
With some degree of depletion I set off for sets of bilateral breathing gradually increasing the SPM to finally 66SPM, the rationale being that my cadence is well below that usually recommended. I get it helped keep up the rhythm of the sets and doesn't need a leading arm to be held for ages.
It was hard to review the times and link back to stroke rate (the Garmin recorded stroke rate is averaged with an initial glide) but it does seem that somewhere around 64SPM may be optimum. I was surprised how comfortable I felt doing this and easily managed 100m sets and included a 200m set when I felt that my pace had been interrupted. None of the sets were fast, around 2:25min/100m at best, but the important thing is that it felt manageable with bilateral breathing. It would be great if I could do that for 400m or more, but in reality I suspect I'd be over 10 minutes.
Anyway, come this morning's run I think the swimming effort was apparent! I struggled with every ascent, couldn't find a comfortable temperature and was glad to get back home. It was a good job that I'd set off with an intention to be 'slow' as if I'd been hoping for a record I'd have been disappointed. But this all makes sense, I can't expect to make gains on consecutive days.