I have gone full-on crazy with this plan. When I am at home, I have a hill that provides the necessary grade and distance to work for ~2min and gain 200 feet elevation at LT heartrate. When traveling, which I do a lot, I require a building with a stairwell that has 20 stories or more to allow 2Min of work. There are not a lot of hotels or parking garages that tall outside of medium/big cities, so when not at home or in a city with tall buildings, I have reverted to a program I used a lot in years past for "work capacity," which is a melding of this program with a Mountain Tactical Institute (MTI) program using shuttle runs in a SE style.
Essentially, I mark of ~25 yards, ~35 yards and ~50 yards. Then I start my timer for 2 minutes and run (not jog, but not sprint) between the 25-yard marks until my HR hits ~158 bpm. Then, I extend the runs out to the 35- and 50-yard marks as needed to keep my HR at LT (shorter distance = higher loading = higher HR). I then rest 3 min (walking around, shaking it out). I continue this until my HR does not get below 130 during a rest period, and then I stop. I did 6 rounds this morning, for a total of 30 min.
As the article below from MTI notes, the metabolic demand is not from running fast but the strength required to slow (eccentric loading) and the strength required to reaccelerate (concentric loading).
From the article: (
Link)
“A shorter shuttle distance is more metabolically demanding,” the coach stated. He didn’t explain why, and I’ve since learned why. Each change of direction takes more strength … first the athlete must eccentrically slow down into the change, then, one stopped and looking the other direction, he must concentrically push off and get back up to speed. All this takes more leg strength, which means more metabolic demand.
I think the above meets the spirit of the SE, but I would love to hear others' opinions.