On the local bicycle club mailing list I saw this link to an interesting report on very short intervals. There are links to the thesis there, so one can review the data itself. The investigators first examined the physiological effects of very short, high intensity intervals, comparing first 8 s work followed by 12 s rest vs 24 s work and 36 s rest. There was little difference physiologically, but the 8/12 sequence was preferred by the subjects. In the following 15 week training study the 8 second / 12 second 20 minute interval training was compared to a 40 min standard cardio workout at 60% of VO2 peak..
For some reason I was very interested in trying it. This morning I put on the heart rate monitor and tried to use my strength exercise as the stimulus- working hard with light weight for 8 seconds, resting for 12 and going continuously for 20 minutes. It didn’t work at all, because as I always find with continuous circuit training I feel the effort, but my heart rate never gets very high even though I’m working hard. I get to audible breathing, but I remain in at a low level of aerobic exertion based on heart rate.
Not wanting to give up, I gave it 20 minutes on the bike. I picked a resistance on the trainer that felt like work for 8 seconds followed by “just turning the pedals over” for 12 seconds. And the workout was quite intense. It’s seems like it’s quite self regulating to get one working very quickly just above lactate threshold. The rest periods are no where near long enough to recover and and the work periods I kept to short of painful, since I was going to be doing this for 20 minutes. Over about 10 minutes then, my heartrate stair-stepped up to about LTHR and slowly moved moved beyond it in the second 10 minutes.
I think it’s a nice way to build intensity on a trainer while stressing the aerobic system primarily. I could see pushing the workout over time to longer than 20 minutes, since I felt a modest amount of fatigue after the workout. I’ll see how ready I am tomorrow, which is the true test of workout intensity, but tonight my guess is that it’s a moderate, not a hard workout and I probably could do it again tomorrow.