Nurmi was born in Turku, Finland, to carpenter Johan Fredrik Nurmi and his wife Matilda Wilhelmiina Laine. Nurmi's siblings, Siiri, Saara, Martti and Lahja, were born in 1898, 1902, 1905 and 1908, respectively. In 1903, the Nurmi family moved from Raunistula into a 40-square-meter apartment in central Turku, where Paavo Nurmi would live until 1932. The young Nurmi and his friends were inspired by the English long-distance runner Alfred Shrubb.

Nurmi stated to a Swedish newspaper that "this is absolutely my last season on the track. I am beginning to get old. I have raced for fifteen years and have had enough of it." However, Nurmi continued running, turning his attention to longer distances. In October, he broke the world records for the 15 km, the 10 miles and the one hour run in Berlin. Nurmi's one-hour record stood for 17 years, until Viljo Heino ran 129 metres further in 1945. In January 1929, Nurmi started his second U.S. tour from Brooklyn. He suffered his first-ever defeat in the mile to Ray Conger at the indoor Wanamaker Mile. Nurmi was seven seconds slower than in his world record run in 1925, and it was immediately speculated if the mile had become too short a distance for him. In 1930, he set a new world record for the 20 km. In July 1931, Nurmi showed he still had pace for the shorter distances by beating Lauri Lehtinen, Lauri Virtanen and Volmari Iso-Hollo, and breaking the world record on the now-rare two miles. He was the first runner to complete the distance in less than nine minutes. Nurmi planned to compete only in the 10,000 m and the marathon in the 1932 Summer Olympics in Los Angeles, stating that he "won't enter the 5000 metres for Finland has at least three excellent men for that event."  In April 1932, the executive council of the International Amateur Athletics Federation (IAAF) suspended Nurmi from international athletics events pending an investigation into his amateur status by the Finnish Athletics Federation. The Finnish authorities criticized the IAAF for acting without a hearing, but agreed to launch an investigation. It was customary of the IAAF to accept the final decision of its national branch, and the Associated Press wrote that "there is little doubt that if the Finnish federation clears Nurmi the international body will accept its decision without question." A week later, the Finnish Athletics Federation ruled in favor of Nurmi, finding no evidence for the allegations of professionalism. Nurmi was hopeful that his suspension would be lifted in time for the Games.  On 26 June 1932 Nurmi started his first marathon at the Olympic trials. Not drinking a drop of liquid, he ran the old-style 'short marathon' of 40.2 km (25 miles) in 2:22:03.8 -- on the pace to finish in about 2:29:00, just under Albert Michelsen's marathon world record of 2:29:01.8. At the time, he led Armas Toivonen, the eventual Olympic bronze medalist, by six minutes. Nurmi's time was the new unofficial world record for the short marathon. Confident that he had done enough, Nurmi stopped and retired from the race owing to problems with his Achilles tendon. The Finnish Olympic Committee entered Nurmi for both the 10,000 m and the marathon. The Guardian reported that "some of his trial times were almost unbelievable," and Nurmi went on to train at the Olympic Village in Los Angeles despite his injury. Nurmi had set his heart on ending his career with a marathon gold medal, as Kolehmainen had done shortly after the First World War.

Answer the following question by taking a quote from the article: When did his problems with his Achilles tendon began?