more weighted lunges and squats....ouch

Today was a treat at the gym. I had a bar that weighted 45 lbs. I had to heft the thing up and over my head, so it was on my shoulders, at which point I did 15 squats. Then I had to bring it back over my head, and do 15 over head presses with it. Then, still holding the bar, arms straight down front, 15 dead lifts. And to finish it off, I had to heft it back up overhead onto my back and do 15 lunges per leg. I finally was able to set the bar down--given that I could get it back up over my head--and rest for about 45 seconds. Then I started over again. I did 4 sets of this. Those lunges are torture. I had butt cramps and I thought for sure my knees were going to give way.