collegiate D3 xc runner and this semester I have been noticing that I will fatigue quick in interval workouts. Im not anything special with ~26:45 PR on a decently quick course. But I will do one mile rep or a few 1k reps and then be fatigued and cant do anything faster than tempo. im not over exerting myself on the early reps. For example I hit a 5:30 in my first rep mid september and then I hit a 5:55 and then couldnt break 6 and dropped from the workout. I figure 5:30 isnt too fast for me factoring in I am not in the racing shape I was in when I ran my 26:45 time. What are some possible reasons I should look into? I take my easy days at 7:30-7:45 pace so I dont think its running too hard on those days