thanks!
on another note, vag's last post reminded me that my garmin volunteered to me after the sprint workout last weekend that i have a new VO2max of 56. no idea how it calculated that - i never wear it at rest so not sure how it's guessing my resting heart rate - or even that estimating my VO2max was a service that my garmin offered. but lol, i'll take it! that puts me in the 95.8th percentile of 32-year-olds, which honestly seems about right. most people are not fit at all. also i went to the local NHS clinic yesterday to get registered and my pulse was 49. middle of the afternoon, no special rest or breathing to get it down. happy about that. should measure it first thing in the morning sometime soon.
EDIT: after snooping around a bit i think it's probably safe to assume that my VO2max is somewhere between 54 and 58. former uses my max measured HR from the race-pace intervals last week, latter uses mayo clinic estimator of 220-age; both use 49 as RHR. not sure that information is much use but there you go.