The Olympic Journey: How Far, How Fast?

From Roger Bannister's four-minute mile to Usain Bolt's 100m world record, athletes are obsessed with running quicker and pushing themselves further. Ahead of the athletics World Championships, Gabby speaks to some of the record breakers and asks whether the men's 100m could be run in less than nine seconds. Can anyone run a marathon in under two hours? What are the great records still to fall?. … MORE