The 50-metre freestyle race pits the fastest eight male and female swimmers from the two-day meet, which attracted 430 swimmers from NSW and the ACT, against each other in a sprint for a $100 cheque.

Zhang defended her title from lane four, beating Georgia Baker from Orange, NSW and local swimmer, Imogen Schiwy, despite favouring longer distance events and swimming against girls two years older.

''I've had a bit of an easy weekend just doing a few 50s and swims I don't usually do'' Zhang said.

''Fifty isn't my strongest event … [generally] I swim 100 through 800m freestyle.''

In the men's event the youngest swimmer in the field, Matthew Wilson, broke his personal best by one second to win the cash in 24.39 seconds.

Wilson, from Springwood in the lower Blue Mountains of NSW, only turned 14 on Saturday and beat locals Luke Hinchcliffe, the veteran of the field at 25, and 18-year-old William Pulley.

Wilson is also not a 50-metre specialist, preferring the 200m breaststroke and individual medley, but showed he is a swimmer to watch in the future.