Sounds weird. I checked Denver altitude and it is hardly air sickness territory.
You need to go significantly higher in the nearby mountains to actually feel the effects of elevation on your breathing, fatigue and brain.
You need to go significantly higher in the nearby mountains to actually feel the effects of elevation on your breathing, fatigue and brain.
It's not actually unknown to get altitude sickness in Denver, it is one of the things the city warns about - going skiing at higher altitudes as well of course - but poor health, and just the speed which you change to that altitude, even on a train, are issues.