Born in Waimate on 4 August 1927, Forsythe was the son of Francis Forsythe and Jessie Dodds Forsythe (née Currie).[1][2]
Representing Hawke's Bay/Poverty Bay, Forsythe won two New Zealand national athletics titles in the triple jump, in 1946 and 1948.[3]
At the 1950 British Empire Games in Auckland, Forsythe represented New Zealand in both the long jump and triple jump.[4] He finished in fourth place in the long jump with a best leap of 23 ft 3 in (7.09 m), and fifth in the triple jump, recording a best distance of 46 ft 7+3⁄4 in (14.22 m).[5]