some of the muslims can be pretty intense.

part of it is fear of retribution amongst their own for getting too close to westerners. So some of them double down their efforts to maintain their customs/traditions/beliefs.

Personally, I would have a really hard time in the gym if I were muslim observing Ramadan.

But then again, there are not too many muslims there, that I've observed, that are as interested in their physiques as some westerners are. They are, after all, fairly spiritual......