Adlington was stunned by her display

Rebecca Adlington shaved two seconds off her own British and Commonwealth 400m freestyle record on the final day of the ASA Championships.

She stretched ahead in the final 50m to win in four minutes 2.80 seconds after a close battle with Joanne Jackson.

The time made her the third fastest woman this year and fourth fastest in history over the distance.

"That was unbelievable. I just don't understand how I've done that time," said Mansfield's Adlington, 19.

"I felt awful this morning. I've been sluggish and heavy through the water and I didn't think I could go that fast.

"I expected a 4:08 and would have been happy with that."

Jackson took silver in a time of 4:05.49, with Jazmin Carlin winning bronze in 4:16.79.

Adlington, from Mansfield, has been in superb form this year.

She broke the longest-standing British women's record in the 800m freestyle in April.

Sarah Hardcastle had held the record since 1986, but Adlington destroyed it by more than five seconds at the Olympic trials in Sheffield.