What kind of burn-out would be involved? When I think of that, I personally think of women and men who are overworking, and also doing too much outside of work, not sleeping enough, probably poor nutrition with lots of coffee or tea.
On the other hand, people who say they are burned out sometimes mean they are bored and limited in their lives and work, and while not depressed, they don't find a lot of pleasure or stimulation in every day.
Those are coming from quite different perspectives in terms of health. What is it from your point of view?
Perhaps a good place to start is to lay out the parameters of what burn out is (and isn't) for the purposes of this study. After that, we would then be in a much better position to find appropriate candidates.