I used to do that in competition (obstacle pole buck) when I was at college in the '70's. The only difference from what was done there was that we had to make two cuts on the log, both with the bottom of the bar ie from the left and right. The other thing was I would carry the saw by the rear handle and start it as soon as my foot hit the mark (the second paint line on the log). The saw had to be turned off as you crossed the upper line on the way back.
I don't think we ever wore ppe except caulks, but we may have wore chaps (can't remember). None of the saws had chain brakes on them as they either hadn't been developed or were not installed as standard equipment.
It looks more dangerous than it really is. As long as you had good balance, its pretty easy to do. I went to a two year college (3 for specialty programs) at that time, so the most experience anyone had was 3 years. The only accident I remember on our team was someone doing the underhand chop (where you stand on the log you're chopping) and he cut through 1 chop sooner than he anticipated and the axe slid out of his hands, went straight up in the air and hit him on the back on the way down. Just a minor cut as he was jumping out of the way.