Gone are the days when Genzebe Dibaba s form would take a dip during the outdoor season.

Two years ago in Moscow, Mo Farah completed the second part of his distance double when he unleashed a sizzling 53.44 last lap to successfully defend the title he had first won in 2011.

Perhaps the biggest obstacle Genzebe Dibaba must overcome in her attempt to win the 5000m is the competition timetable.

After the great miler Herb Elliott had thrashed a field of the world s best, Ireland s Olympic champion miler Ron Delany wondered whether there was any way to beat Elliott.

Tirunesh Dibaba, Linet Masai and Vivian Cheruiyot have won the past nine global 10,000m titles between them.

Marathons have always been notoriously difficult to predict. Adding to the complexity is that championship marathons are almost invariably run as races in unfavourable conditions while most of the assessable form comes from performances in cooler condi...