Ykema made his international debut at the 1981 World Speed Skating Sprint Championship . There he finished 20th in the all-around competition. In 1984 he took part in his first Winter Olympics in Sarajevo . There he reached ranks 14 and 20 over 500 and 1000 meters respectively. His most successful season was 1987/88 . At the Sprint World Championship in West Allis , he finished sixth, his best World Championship placement of his career. At the Winter Olympics in Calgary , he was able to win the silver medal over 500 meters. He also won three World Cups this season, two over 500 meters and one over 1000 meters. Ykema also won three national sprint championship titles in 1982, 1987 and 1988.
After retiring, Ykema worked as a real estate agent for about 15 years . In 2008 he returned to speed skating as an assistant coach for a small Dutch professional team.