I do a power hill climb (my name for it

)
Basically, it goes like this...
I start the climb with just long stride hiking. Probably like 12 or 14% grade or something. That takes me up about 100 feet. When it levels out, I start jogging, to the next steep incline. Long stride, hike up that, another 150 feet. Then jog all the way down the back side. Turn around, and hike as fast and hard as I can, all the way to the top. Jog all the way down the front.
Turn around, and do the whole hill again.
The total miles covered is 2.6... and now that I'm adding some flat ground running after wards, closer to 3 miles total (checked it with Google Earth) and the total vertical climb (counting the climb, up the front, up the back, up the front, and up the back again) is about 1100 feet vertically.
The whole thing took me 36min 34 seconds, the first time I tried it.... and I seriously thought it might kill me ! Or, at the very least, that I'd pass out.
Well, it still kicks my arse, but I've gotten it down to 26min 34 sec now, and I bounce back from it much quicker, after wards. Oh, and now that I'm doing it in substantially less than 30 minutes, I continue to run on flat ground, to keep the whole workout to 30 minutes.
Talking to some fitness experts, I've heard that even with running, interval training is all the latest rage.... and that basically, my hard-core up hills, followed by faster, but easier downhills, are creating, in effect, intervals.
My only problem is, I've dealt from foot pain (all started when I was obese, and killing myself with my horrendous diet) but I'm still paying for it, after a run.
But my foot is better this morning, so I can go beat on it again this evening.
Peace,
Fish