Education
He attended Children and Youth Sports School of Sovetsky District, Khanty–Mansi Autonomous Okrug, where his first trainer was Valery Ukhov.
He attended Children and Youth Sports School of Sovetsky District, Khanty–Mansi Autonomous Okrug, where his first trainer was Valery Ukhov.
Dementyev"s first international success was in 2001 at the Junior World Championship. This margin of victory eclipsed the previous record of 4.9 seconds set at the 1984 Winter Olympics in Sarajevo between fellow Swedes Thomas Wassberg and Gunde Svan. Dementyev has two 4×10 km medals at the FIS Nordic World Ski Championships with a silver in 2007 and a bronze in 2005.
His best individual finish at the FIS Nordic World Ski Championships was 22nd in the 15 km + 15 km double pursuit in 2005.
On 25 August 2009, Russian newssite russiatoday.com reported that Dementyev has tested positive for recombinant erythropoietin (EPO). He returned in 2011 after a two-year ban.