 Complete the following phrase:  He represented Czechoslovakia for most of his career and in addition to his Olympic gold, won two silver medals at the World Championships in Athletics 1983 and 1987 and one gold and one silver at the European Athletics Championships for his country. He was a two-time champion at the European Athletics Indoor Championships, winning in 1987 and 1988 over distances of 3000 m and 5000 m, respectively. He was a four-time participant at the IAAF World Race Walking Cup and his best performance was a win over 20 km at the 1983 IAAF World Race Walking Cup, becoming his countrys first victor at the competition. He had previously shown his developing talent as a youngster with a win at the 