He has lost count of how many medals he has won since he first competed in Special Olympics in 1985.
''I hang them all on coathangers and they jangle together,'' he said after winning the 50m mixed walk in a time of 3min at the Caledonian Ground yesterday.
Teammate Joanna Franklin was second in 3min 05sec and Donna Flavell (Hutt Valley) third.
Thornhill (38) competed in gymnastics at first and won a medal when he competed in an international event at Hobart in 1998.
He used to enter the running events but it was too stressful on his body and he now enjoys the walks and throwing the softball.
There are eight athletes in the North Taranaki team of 41 competitors and coaching staff.
''Gymnastics helped Michael physically and made a big difference to his life,'' his mother said.
''Taking part in Special Olympics has given him a focus. He has made friends and it has had helped him develop his personality.
''He meets up with old friends at each Summer Games. Special Olympics is just one big happy family.''
The best sprinter on the first day of athletics at the Summer Games was Kwame Williams-Accra (Wellington) who won his 200m in a fast 26.95sec. Born in England, he came to New Zealand at the age of 9.
He has won a lot of medals in AWD events at the New Zealand secondary schools championships.
The other strong sprinting performance came from Canterbury's David Thomas (41) who won his 200m in 29.18sec, wearing his new bright blue spikes.
Another experienced athlete was Canterbury's Robin Ford (43) who won the softball throw with a personal best 21.68m.
Hutt Valley's Caitlin Pampalone (20) won the women's shot put with 6.21m with her first throw. Fifteen-year-old Laura Montgomery (Halswell College) was second with a personal best 6.09m.
