Sex that lasts over an hour, with continued intent; if only an hour and a half or so, partners may only be distracted during
sex. During 'marathon
sex,' as opposed to marathons, small breaks are sometimes taken, akin to stretches during exercise, which is part of what the 'marathon' is... exercise, for both partners, in every case, though! For it to last so
long, mutual exercising, and most especially pleasure, throughout the entire event, are both prime requisites.