Real Dictionary

legwork
uncountable noun: You use legwork to refer to work that involves physical activity such as interviewing people or gathering information, especially when this work forms the basis of other, more intellectual work.

legwork in American English
routine work that is necessary to a job, as that of a news reporter, involving, typically, walking or driving from place to place, away from the office
noun: work or research involving extensive walking or traveling about, usually away from one's office, as in gathering data for a book, a legal action, etc.

legwork in British English
noun: work that involves travelling on foot or as if on foot