Trying searching for HIIT (High Intensity Interval Training), I've never heard of FIIT but I'd bet they are they same thing.
The InterWebz will have a ton of info for HIIT for all abilities.
My personal experience is that I do better with HIIT on a bike than with running, as all-out sprinting leaves me too injury prone at my age.
I also tried a HIIT routine with jump squats, burpees, mountain climbers, etc. and it was darn hard and I'm sure very effective. But once again made it easy to get injured.