leg·work 
/ˈlɛgˌwɚk/ noun
/ˈlɛgˌwɚk/ noun [noncount] : the active physical work that is involved in doing something
▪ I wrote the article myself, but my assistant gathered the information and did most of the other legwork.
▪ I wrote the article myself, but my assistant gathered the information and did most of the other legwork.
