I like to run sprints but I got thinking about when I get tired and am I still getting the benefits of HIIT. So here's my question...... I run sprints up a hill that's moderately elevated and roughly 150 yards long. I shoot for 8 sprints and a light jog back down. It takes me about 1 1/2 miles to get there so that's my warm up. Ok... If I am giving 90-95% effort on all my runs but the last 2-3 sprints I start to get tired and even though I'm still giving max effort at the end, in reality it's only 70-75 percent of when I started, are the last few runs as effective as the start of the session?