1927, Porterfield, William M., Bamboo and its uses in China, Chinese Government Bureau of Economic Information, Booklet Series 2, p.40. Cited in David Farrelly, The Book of Bamboo, p.25; Sierra Club Books, 1984. Big bamboo poles are used for carrying heavy loads in China. In the cities one hears the familiar antiphonal “heigh-ho'ing”, indicating that a heavy load is being moved somewhere. The heavier the load, the louder and more agonized the chant.
Source: wiktionary