Exercise while TTC

I read an article with findings from a single study that vigorous exercise (in this case, working out hard enough that you don't have the breath to hold a conversation) while TTC can actually hinder getting pregnant, unless you were clinically obese, in which case loosing weight was needed to conceive. It was only one study, so certainly not scientific proof, but it still made me think and wonder. Has anyone heard anything about this from a doctor, or noticed trends in their life or those around them?