Jackson drops expectations after her body is ravaged by winter bugs

Jackson, the former 400metres freestyle world record holder, has only been able to complete five weeks of work within her usual heavy training phase due to severe asthma brought about by illnesses such as flu and a respiratory infection over the winter.

As her training has been decimated, the 23-year-old has little expectation going into the championships at Ponds Forge, where she will fight it out for places on the Commonwealth and European teams.

"I've never been through anything like this and it's been quite scary," said Jackson. "I've had asthma before but it's never been as severe and I've never experienced the panic that comes with not knowing how to handle it.

"I'm receiving physio treatment twice a day because I'm breathing so hard while trying to train that my ribs keep popping out. I'm desperate to train well and get back to my best but it's hard given my health.

"I have no expectation of myself this year. I'm training the best I can but realistically I have a long way to go to be near my best. I am aiming for the Commonwealth Games in October and will be targeting qualification events later in the year."

Jackson will be joined by double Olympic champion Rebecca Adlington and world champions Gemma Spofforth and Liam Tancock at the event from March 29-April 3.

The season has already got off to a flying start for the British swimmers who had a convincing win over Germany in last month's head to head in Swansea, especially welcome given the return to textile suits.

Head coach Dennis Pursley said: "This event is a little more unknown than our swimmers are used to because it will be their first chance to get a peak performance with the new suit rule.

"The Australians have just had their trials so that will give our swimmers some times to aim towards."