Notes
erm, 2.4 or 2.7 km, probably the latter, lost count. total min around 20mins. but I didn't have the lap function on all the time.
I wouldn't really call this a fartlek, it was slow running and a fast 300m in the middle...but found no better definition of this :)
I went with a running friend (who's still a beginner).
I had him keep his HR low, slow pace, for 600m, way under MAF of course, then I wanted to run a max. 300m and I did it :P HR shot up to 191 after 100m and went to 195 by end of the 300m, it was near max speed for the first half and was truly max speed in the second half of the 300m, call that sprinting. it felt crazy good.
then slow running again, caught up with my friend and we ran a little more until he wanted to finish.
HR was in 140's in the slow 600m before starting this fast 300m, and it would go down to 160 for the last part of the slow running and was held there. perhaps it was working hard to remove lactate? :P (even though I didn't feel any lactate or H+, because it was not a long enough distance for the full buildup of them.)
after stopping the entire workout, HR recovered a few mins later to below 100.