Helen is now past the halfway mark on her 500-mile Sport Relief Challenge to the South Pole. In this episode, she takes the decision to park her fastest mode of transport - the kites - as she wants to try and complete the remaining miles with just the bike and skis. Helen's decision to ditch the kites does not go down well with her Norwegian team-mate Niklas. Now the pair will have to travel at least 14 hours a day if they have any chance of completing the challenge in time. However, the constant physical demands of the longer days and the cold of Antarctica starts to affect Helen's health as she picks up a nasty cough. Has ditching the kites put her whole trip in jeopardy?

• Helen Skelton