In all seriousness, if you are not used to intense heat like that, you can get a sick feeling. Ive done many courses in first aid. You can get heat exhaustion easily, even if it is just walking in heat. If someone is in a class without access to water/means of keeping cool or cooling down, they may feel sick. That is our body at work, not how we are raised lol.
Lol I have treated a million cases of Heat Exhaustion. It sucks. People can be fine for awhile then all the sudden they show symptoms of it, and they need to slow down.