I would presume that the standards are adjusted to fit the species of the crewman, with some basic minimums for all personnel regardless of species. Let's say there is a species who can typically run a three-minute mile, whereas the human record stands at four minutes (or just under). Human fitness standard say you must be able to run an eight-minute mile to pass the test, but members in this species need to run a six-minute mile. On the other hand, a species who typically can't run a full mile before dropping over, few of them could even join the service and only if they can run a twelve-minute mile. Does that make sense to anyone else?