5x5 Effects on Muscular Endurance
 

So I was doing a 5x5 for a couple of months, mostly power moves to build my strength back up a little bit after not being in the gym for a while. I recently took about a 10 day break during finals for school and got back in there today. While doing my sets I noticed that the fatigue would hit me rather quickly, as in, I would be able to hit 8 reps, then the 9th would become way to hard to even push half way. In fact I failed completely on back to back sets and where the rep just before I felt perfectly fine.

Is my body used to pushing out about 5 reps and fatigues very quickly after this? Or is it just chalked up to the fact that I've been a little bit sick lately?

Probably both, I know when I am sick that my endurance is crap. But if you are used to doing only 5 rep sets as well, than higher reps are difficult at first.

I noticed when I switched from strictly power lifting back over to hypertrophy training that I was struggling to get through workouts, but my body adapted within a couple days.