z6 interval thread

whoawhoa said:

I have some questions about z6 intervals, (Coggan levels) so here goes!

The time range for these intervals (.5 to 3 min) is fairly large. Are the benefits of a set of 30 second intervals different than a set of 2 min intervals? It seems to me like 30 second intervals might develop 1 minutish power, while the 2 minutes would maybe put a "peak" on vo2max power. Anyone have experience with this?

I think you are on the right track...
Shorter intervals by nature allow you to train at a higher absolute power, but since such a short effort will not totally deplete your anaerobic 'reserves', these efforts are about training your 'anaerobic power' (i.e.: training your muslces to get the power up near peak values).
Longer intervals must be performed at a lower absolute power and will demand that you tap deep into your anaerobic reserves, if not more or less deplete them, to keep up a high average power for the full duration of the interval. In this case, you are doing more to train your 'anaerobic capacity' (i.e.: the total amount of energy you can deliver to the pedals via anerobic metabolism w/o a signficant drop in power ouput).
Since aerobic contribution to such intervals increases significantly beyond ~30sec, Coggan Zone 6 intervals >30sec will have an increasing effect on VO2peak as the interval duration increases; the magnitude of which will depend on your training state.