Triple Olympic gold medallist Jodie Henry knows she is running out of time, but two strong swims at the Victorian championships have buoyed her hopes of defending her 100m crown in Beijing.

Henry put aside illness and infection which have hampered her race fitness to qualify fourth fastest for Monday night's women's 50m freestyle final.

After withdrawing from the 100m, Henry emerged for the 50m heats on Sunday morning and swam a respectable 25.76 seconds.

She then went .09sec faster in the semi-finals at the Melbourne Sports and Aquatic Centre - enough to give her fourth fastest time behind American Natalie Coughlin (25.45), Queenslander Alice Mills (25.48) and West Australian Sally Foster (25.65).

Henry has endured a difficult time of late, twice switching coaches, being disqualified from one event at the Queensland titles last month and withdrawing from another because of illness.

But the 24-year-old was happy with getting a much-needed competitive hitout after her health had threatened to again derail her at this meet.

"It was painful to swim before but it's not now, so that's good," Henry said after her semi-final.

"Girl's sort of area stuff - it's a little bit embarrassing but it's something that happens and you can't control when it happens."

Henry's disrupted preparation has led to worry about her recent lack of racing with the national Olympic Games selection trials just three months away.

National coach Alan Thompson voiced his concerns over her build-up and Henry admitted she still had a lot of work to do to get to a point where she would be able to make the Olympic team.

Henry must finish first or second in the 100m at the trials in Sydney from March 22 to 29 to earn the right to defend the individual 100m crown she won in Athens four years ago.

"I've only got 12 weeks to go and I'm not where I should be, I'm not where the others are, but it's good to see I've got a little bit of speed because I didn't think I had any," Henry said.

"I have no idea what's going to happen between now and then (the trials), but my main focus is to stay healthy so I can get in the water and do the miles I need to do."

Henry said she remained keen to swim the 200m freestyle on the final day of the meet on Tuesday to further boost her race fitness.

In other events on Sunday night, Victorian Matt Targett won the men's 100m freestyle title in 50.04 and NSW swimmer Daniel Arnamnant won his second gold medal of the meet in the 100m backstroke.

Felicity Galvez added the 200m butterfly to the 100m title she won the previous night, while world 800m and 1,500m champion Kate Ziegler spreadeagled the field to win the women's 400m freestyle.

The American finished more than eight seconds ahead of nearest rival and fellow American Katie Gardocki - 4:06.17 to 4:14.25.

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