I think that with time your HR will drop faster and the delta will increase.

Many plans define their ranges differently... is this a plan you are using?

For example, my plan only does 4 ranges, and defines them at the top of the page...

BBB -

I had always assumed that interval training involved exceeding your LT. Otherwise, you should be able to maintain the high-end pace of the interval for extended periods of time.

Last night, though, I was reading an older book on bike training (1980s), and it discussed two different types of interval training --- the main difference being whether or not you cross the lactate threshhold.

And now you talk of strictly staying below the LT. Hey, what am I supposed to do? Well, I don't do intervals anyway, so I guess it doesn't matter. :rolleyes:

Here's another discussion I just saw:

"In general, there are a couple rules of thumb when performing VO2max specific intervals. The first rule is that you should perform these intervals at an effort between 90% and 105% of your VO2max power (pVO2max). The second rule is that the intervals should last between 3 minute and 10 minute in duration. Rule one and two are interrelated in that, if performing an interval at 105% of VO2max power, one will likely only be able to sustain the effort for approximately 3 minutes. Conversely, if performing the interval for 10 minutes, the intensity will necessarily be lower, in the vicinity of 90% of pVO2max. If we adhere to the training principle of specificity, the intervals should be performed at 100 % of pVO2max. In this case, the duration should be 3 to 5 minutes. Highly trained, or elite athletes have been shown to sustain intervals at the effort associated with VO2max for up to 7 or 8 minutes, but this is a gut busting effort, which likely isn’t necessary to elicit the training effect. Further, in order to introduce the training principle of overload, one could perform multiple short intervals, and theoretically apply a greater overload than a single longer interval.

You might ask, “why not perform intervals harder than 105% pVO2max?� Again, because at intensities of 110% pVO2max the duration of the interval will necessarily be short; likely shorter than 3 minutes. One thing to take into consideration is that at the start of an interval, increased oxygen consumption takes anywhere from 60-180 seconds to reach the point of VO2max, therefore, a two minute interval at 120% pVO2max may not elicit VO2max, and certainly won’t stimulate adaptations that would optimally improve VO2max (this lag in the response of VO2 is also why monitoring heart rate is of little value when attempting to gauge the intensity of these intervals). Performing an effort at a greater intensity than 100% of pVO2max, does not stimulate greater oxygen consumption; our VO2max is just that, the maximal rate of oxygen utilization, and any effort above that needs to be fueled by anaerobic metabolism. So, if one were to perform an interval for 4 minutes at pVO2max, they might achieve actual VO2max after 90 seconds and spend the remaining 2.5 minutes stressing that system. Figure 1 presents a conceptual representation of the relationship between the length of the interval, given the intensity, and the resulting time that one spends at VO2max. As can be seen from the diagram, intervals performed above 100% pVO2max result in little, if any, time actually at VO2max. Similarly, although intervals performed at 95% pVO2max, that last a total of 8 minutes, might result in 5 minutes of time spent actually at VO2max, if we decrease the intensity only a couple percent, and extend the duration past 10 minutes, the individual never actually attains VO2max, and hence spends no time at VO2max for a tough interval; high cost, little gain. This diagram is conceptual in nature, and individual differences will exist regarding time spent at VO2max given duration and intensity, but the premise generally holds true. Figure 1. Intensity versus time spent at VO2max. -------- Intensity (% pVO2max) - - - - - Time spent at VO2max.

Other considerations when performing intervals are the number of repetitions to perform, and the rest period between intervals. With regard to number of repetitions, the accumulated interval time should be between 12 and 25 minute total, and the rest duration is typically equal to the work duration.

In short, what are the points to consider when attempting VO2max intervals?

1) Interval duration should be minimally 3 minutes and maximally 10 minutes in length.
2) Intensity of the interval should be minimally 90 % pVO2max and maximally 105% pVO2max.
3) Total interval work time should be minimally 12 minutes and maximally 25 minutes.
4) The rest between interval is generally equal to the work interval itself.

By using these guidelines, you should be able to devise an interval training approach that will target adaptations to VO2max, and that will result in improved overall performance in diverse cycling events."
http://www.peakscoachinggroup.com/freeinfo/Intervals_for_vo2max.html

Too much pseudo-scientific mumbo-jumbo for me. Some days I'll train hard, some days I'll train easy, and that'll have to be good enough.

kyilee - best i can figure so far...my Z2 is 125-142 and my Z3 is 142-157 with LT at 157. (i've only done a running 30min test once.)

BBB - my plan doesn't drop me to Z1 for this interval, but it seems from your comments that the idea is the maximize the delta with sufficient recovery to keep going. so I guess it probably isn't a killer to have to slow to walk just to bump down my HR briefly?

Hitman - i'll read that tonight at home with bit of scotch when i can read it three times to understand it. ;) but it looks helpful, thanks!

BBB --

That table rocks! Thanks.
I disagree with a few of the zone levels my coach is using (they seem a bit too broad, because the 70-85% is all one zone, where I thought there were significantly different types of workouts in that range) and this helps me get a feeling on how I might adjust things.

Yeah... I'm still just amused then whenever I do HR training it's your voice I hear keeping me at it... and I've never even heard your voice!

BBB - it looks like my Z2-Z3 "intervals" are not quite on the same page as your intervals, but I'll get there eventually. :)

thanks for the extra info!