How to Measure Intervals Effectively

Grant Holicky talks about focusing more on how the athlete felt and how hard they pushed to see if the intervals were effective. One of the things that I'm looking for immediately is their reaction to the workout. That is my trigger to then go dig deeper into the workout and see what they were able to do. It's interesting because a lot of athletes are like, oh, if I write, I felt bad. He assumes I did bad.