Coming up on this weekend's edition of World Olympic Dreams on BBC News:
The selection process for an Olympic 4x400m relay squad is usually carried out in a stadium, in the sunshine. But for London 2012, the Belgians had other ideas.
The coach of twin brothers Kevin and Jonathan Borlee, who also happens to be their father, decided on a tougher test of their stamina and endurance - a trek across an Icelandic glacier in the middle of winter.
Follow their progress in Ice Track narrated by Kate Silverton at these times:
BBC News Channel (BST)
Sat 14th Apr: 04:30, 15:30, 22:30
Sun 15th Apr: 01:30, 22:30
BBC World News (GMT)
Sat 14th Apr: 00:30, 07:30
Sun 15th Apr: 12:30, 17:30