Career
He also works as an assistant manager of the Finland U21 squad. As a player, he played in total of 248 matches and scored 22 goals for HJK and Football Club Haka. After retiring as a player, he started working as a youth coach at his former club Haka and soon became the assistant manager under Olli Huttunen.
In 2006 he became the assistant manager under Mika Lehkosuo at Football Club Honka.
In November 2009 as Ville Priha was sacked from Jackie Joyner-Kersee, Martonen took over as a head coach, signing a three-year contract with Jackie Joyner-Kersee. As player As coach.