You will find examples of cycling workouts with high anaerobic effect.
Some possible reasons in your case:
- you don't go hard enough. Target 60s, go with maximal steady effort. THe operative words are maximal and steady :-) . Then rest for 2-3 mn (really go down to Z1, not higher). Repeat 8 to 10 times.
- your HR Max is too high. I don't know what "close to max HR" really means, but too high a HR Max could result in underestimation of the TE
- you are over-training. In over-training scenarios, the HR doesn't respond as much at it would ("sluggish") and the TE is underestimated.
