In March 1937 he was third in the Lahti Ski Games over 17 km. In 1938 he first took part in a Nordic World Cup, but his international career was interrupted by World War II during his prime; During the war he became Finnish champion twice: in 1943 over 18 km and in 1944 over 30 km. At the Lahti Ski Games in 1943 he won over 18 km and took second place over 50 km. The following year he took third place over 18 km.
Silvennoinen was a police officer by profession. After his active time, he remained loyal to cross-country skiing as a trainer and official of the Lahti Ski Club and the Finnish Ski Association .
literature
Markku Siukonen: Urheilukunniamme puolustajat. Suomen olympiaedustajat 1906-2000 . Graface Jyväskylä, 2001, ISBN 951-98673-1-7 , p. 308.