 Complete the following phrase:  A new technique, skate skiing, was experimented with early in the 20th Century, but was not widely adopted until the 1980s. Johan Grøttumsbråten used the skating technique at the 1931 World Championship in Oberhof, one of the earliest recorded use of skating in competitive cross-country skiing. This technique was later used in ski orienteering in the 1960s on roads and other firm surfaces. It became widespread during the 1980s after the success of Bill Koch United States in 