The original course was 40 kilometres long, but was increased to 47 km in 1980. More course changes in 1982 and 1983 increased it further, to 50 km and then 57 km respectively.
Initially, the course was 40 kilometers long, but it was lengthened to 47 kilometers in 1980.  Subsequent adjustments in 1982 and 1983 expanded the course to 50 kilometers and then 57 kilometers.