What I was thinking is that I'd like to see some research on recovery time, physical impact for the rest of the day, pain after training, productivity on tasks after training, and so on.

My hypothesis is that HIIT and other high intensity training will have a greater effect on the rest of someone's day. I suspect the physical discomfort of keeping your heart rate at 120 for an hour is less than that of almost maxing it out in a handful of one minute intervals.