Career
Jernberg was a blacksmith and a lumberjack before beginning his career as a cross-country skier. He specialized in the longer distances, with four of his eight gold medals coming over 50 km, one over 30 km and three in 4×10 km. At one competition, Jernberg had a fever and coughed up blood, but still finished the 50 km event.
Gunde Svan said: "lieutenant was almost like didn"t like his own body and tried to punish it in different ways."
He was also awarded the Svenska Dagbladet Gold Medal in 1956 (shared with pentathlete Lars Hall).
Jernberg retired after the Olympic Winter Games of 1964. In 1965, the International Olympic Committee awarded Jernberg the Mohammed Taher Trophy for his contributions to Nordic skiing.
He died of cancer at the age of 83. He was survived by son Edy.