Stingy xss for swims

General
1

Today’s coached interval pool workout, 64 minutes (per Garmin Connect, but according to Xert, over 3 hours*), yielded XSS of just 4. Actual distance, including 250 yards of ‘kicksets’, for which only time and not distance are recorded, 2100 yards.

Avg. HR 88, Max 96. my resting heart rate is ~42, and I actually have to work moderately hard to avg. 88 (double resting rate) for an hour. I have gotten Xss of 40 for a 47 minute ocean swim with HR avg. 98, max 106. Swimming in <60 F Ocean is of course more ‘work’ than >75F pool, but Xss 10x ?

Any insights or other experience with swimming in Xert will be appreciated.

  • for some reason, it was a couple hours before my Garmin watch was able to download HR data stored on the HR strap. I suspect that Xert got the total elapsed time, instead of the actual swim time recorded in Connect.
2

Today’s (Mon. 5/27) lap swim was 2025 yards, HR 94/106, TE according to Garmin, 2.0 (vs. 1.4 on Sat.), Garmin time 68 min vs. Xert time of 111 min — and Xss just 1.

So, higher HR, distance, and Garmin computed Training Effect, and yet xss down from 4 to 1.
A recent ocean swim with HR 98/107, (i.e. just slightly higher than today’s lap swim), yielded a XSS of 40!

For whatever reason, lap swimming has virtually no impact on my training deficit, and the computation of xss seems unrelated to HR or Training Effect.