What Are Intervals? (Part Deux)

In an earlier post, I discussed the issue of recovery time in intervals in reference to an October Running Times article (I can't link because they don't appear to put current content online). The November issue has a report from Pete Pfitzinger that I think ought to clarify things for RT readers.

The optimal ratio of hard running time to recovery time depends primarily on how intensely you run the intervals and only secondarily on the length of the interval. Thus, cruise intervals, which require only a modest amount of recovery time (e.g. 30 second to two minutes) because the intensity is only moderately high, have a relatively high work to recovery ratio, about 5:1. VO2 max intervals are shorter but faster than cruise intervals, with reatively longer recoveries (e.g. 90 seconds to three minute), resuting in a work to recovery ratio of 1:1 to 2:1. Because shorter repetitions to improve your speed are run at an even higher intensity, the recoveries are comparatively long, with a work to recovery ratio of 1:2 to 1:4.

There's not much more I can add to this, other than to recommend that you go buy the issue or go down to your mailbox to see if it's arrived.

(Disclaimer: I do not work for Running Times, although if they're hiring ...)