While scuba diving, nitrogen narcosis stops the instant you ascend a bit (the typical recommendation is to reduce the ambient pressure by one atmosphere). I don’t think there is anything in this study that indicates the effect lasts more than a few minutes after exposure ceases.
Depending on exactly what one's doing, it's easily conceivable that the exposure can be concurrent with the activity. Maybe not football, where lugging around a compressed gas tank on the field is likely impractical if not dangerous, but a sport like Formula 1 or many E-sports would likely be quite conducive for an individual, and other sports like wrestling or swimming could probably be done entirely in a room with a modified atmosphere.
