These data extend the current knowledge base by indicating that acute exercise-induced changes in cognition are disproportionately related to executive control and may be specific to the aerobic exercise domain.Translated: aerobic exercises such as running apparently do something to the brain to make it work better.
How I can tie this to political knowledge, I'm not sure. It's not like we can make people do jumping jacks while watching or reading the news, but it might be interesting to include in a survey items that attempt to tap a respondent's aerobic activities. My guess is, any difference or effect here is lost in the maze of other potential variables that influence political knowledge -- which is usually more long-term memory, than this example. Still cool.