Steph Twell made a disappointing exit from the IAAF World Championships in Berlin when she crashed out in her 1,500m heat on Tuesday.

The world junior champion, who celebrated her 20th birthday on Monday, faded badly on the final lap and finished 12th of the 14 runners in four minutes, 18.23 seconds, well outside her best of 4:03.98.

After the race, a downhearted Twell, a student at St Mary’s College in Twickenham, said: “I am not 100 per cent sure what went wrong myself.

“Each time I made a move, I found I was blocked. Unfortunately, when they went up a gear I couldn’t go with them. I just can’t believe it.

“I have got to analyse the race with my coach and family.”

Before Tuesday’s race, her coach, Mick Woods, who manages the UK Athletics endurance performance centre at St Mary’s, questioned the choice of Portugal as the Great Britain training camp ahead of the World Championships.

He said: “The weather isn’t good for endurance athletes. With temperatures 30 degrees plus, to try and train is very difficult.

“I wouldn’t have come here for final preparation by choice. It would’ve been better for us to have stayed at home.

“Acclimatisation is important but, technically, there shouldn’t be any need for Berlin, as it wouldn’t be anything like as hot.”

Woods understood UK Athletics wanted the team to spend time bonding.

He added: “Part and parcel of any team spirit is to be in the same place and be part of the team process.

“That’s obviously why they wanted to do it.”

Twell also admitted it had been hard in Portugal, pointing out that some days had been very hot, with her body taking longer to recover after training sessions.