Hamman took up athletics at the age of 13 at Vista Nova Primary School in Rondebosch. In 2009 he quit the sport following his disappointment at not qualifying for the 2008 Summer Paralympics in Beijing. He returned to the sport in 2013, and was selected for the South African team o compete at the 2013 IPC Athletics World Championships in Lyon. He took part in the javelin throw and shot put, finishing fifth in the shot, but threw a distance of 45.72 metres in the javelin to take the gold medal. Two years later he competed at the 2015 World Championships in Doha, winning gold in the javelin and silver in the shot put.