Cycling race

On March 15th there was a cycling race in El Alto, at over 4000 meters/ 13,100ft. It was a version of a criterium: 20 laps on an out and back course, totaling about 45km/28miles. I had never raced a criterium before, but I assumed it was going to be harder than a regular road race, and I was right. After every turn there was a severe acceleration, racers trying to break the pack and drop people. After just 4 minutes I saw my heart rate reaching anaerobic levels and I was trying to hang on to the leaders at every turn. I knew there were a bunch of really good riders, but while suffering, I was sure that not many would last until the end. As the race wore on there were less and less people trying to be at the front. Many times a few riders broke away for maybe a minute or less, but didn't get away. Then at some point, I think just after the half way point, I didn't really even see 2 getting away because I was a few places back. They got far away, but after maybe 15 minutes one of them dropped the other and rode away solo, until the finish. I would have been impressed, but I was busy still chasing him taking turns with basically just one other racer, pulling 2-4 others behind us. Luckily those 2-4 were not being "smart" by not taking any pulls, but they were more like dying. At the last turn I was quick and had only one guy ahead of me, then I sprinted away for a moment, but soon the dude who was in the breakaway with the eventual winner but got dropped, easily passed me and kept that 5 meter lead until the finish. So I got 3rd overall. Pretty good. Cycling has been my priority but I'm running and swimming too. After the last turn I peaked 866 watts and averaged 398 watts for one minute. When doing a normal or an easy ride, the wattage is not so different from sea level, but when doing hard intervals, everything seems to be about 50-60 watts lower here at these crazy altitudes. It also looks like that when going hard, the heart rate is lower than at sea level. It's very different riding, running, and swimming here.