I received an interesting question from an athlete today. He asked...
Question: "Is there research available on recovery time vs. Intensity Factor (IF)?"
Explanation: "IF" is a TrainingPeaks and WKO+ term which refers to how hard a workout is relative to the athlete's Functional Threshold Power (bike) or Functional Threshold Pace (run, swim, etc). FTP is similar to anaerobic or lactate threshold--the level of intensity just below the effort at which lactate begins to accumulate. It's when you start to "redline." IF is expressed as a percentage of FTP. So if, for example, your FTP on the bike is 250 watts and you rode your bike during the entire workout at an average of 200 watts, your workout IF would 80% (200 / 250 = 0.8). It's a nice way of talking about how hard a workout was.
My answer: "That's an interesting question. No, I've not seen any research precisely on the relationship of IF and rate of recovery. But as with all things in exercise physiology, the answer would be highly dependent on many factors, mostly related to individuality. For example, one such individual determiner would be what the physiological predisposition of the athlete is as compared with the type of workout done. For example, if the athlete is better adapted to aerobic stress as opposed to anaerobic, and the workout's IF was primarily based on anaerobic intensity, then the rate of recovery could be expected to be slower than for another athlete who is more anaerobically inclined. The opposite pairing would also be true, I believe. And there are many, many more such individual markers of recovery such as age, diet, experience, prior training, type of exercise, sleep, psychological stress, lifestyle, etc. The topic of recovery is very complex."
Conclusion: I don't know.