Eliud Kipchoge moved tantalisingly close to the magic two-hour mark for the men's marathon last year, but a former world record holder and a sports science expert both think it could take another decade or so for the barrier to fall.
Kipchoge's record time of two hours, one minute and 39 seconds, set in Berlin in September, has ignited talk in the athletics world of whether the Kenyan, or perhaps someone else, can dip under two hours sooner rather than later.
