His personal best time is 48.05 seconds, achieved in July 1998 in Paris. Together with Tawanda Chiwira, Phillip Mukomana and Savieri Ngidhi he holds the Zimbabwean record in 4 x 400 metres relay with 3:00.79 minutes, achieved during the heats at the 1997 World Championships in Athens. Harnden also competed for Zimbabwe in both the 1996 and 2000 Summer Olympics.