Marathon Predictions from Half Marathon times

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fetcheveryone Apr 2013 11:27am, 16 Apr 2013 12,568 posts	0 fetcheveryone Hello mon petit choufleur, I'm having a play with race time prediction - in particular looking at the Riegel formula e.g. T2 = T1 x (D2/D1)^1.06 Here's how it translates typical half marathon times into marathon times: 1hr10 = 2hr26 1hr20 = 2hr47 1hr30 = 3hr08 1hr40 = 3hr28 1hr50 = 3hr49 2hrs = 4hr10 2hr10 = 4hr31 2hr20 = 4hr52 2hr30 = 5hr13 How do those predictions work out for you? A close match? Nowhere near? In my case, I have 1hr46 for a half, and 4hrs15 for a marathon, so the prediction is over half an hour out. It's worth considering that training to our potential for a marathon is probably more than twice as hard as training for a half marathon - and I think that many of us fall short of meeting Riegels predictions in this case. So whilst you could argue that if we REALLY tried, we could make those numbers, I think it's of more use to generate a more accurate prediction of the likely outcome. Shout out your numbers and your thoughts - meanwhile I'm beavering away with a spreadsheet of several thousand race performances TTFN Fetch
Crooked-smile Apr 2013 11:30am, 16 Apr 2013 1,536 posts	0 Crooked-smile My current half marathon PB is 1:58, and I have just done my second marathon in 4:39 which I was delighted with. I think 4:10 is too ambitious for me just now, though 4:00 is my ultimate goal... But I'd expect my HM time to be faster by then!
Pestomum Apr 2013 11:38am, 16 Apr 2013 2,599 posts	0 Pestomum HM PB 2:16, marathon 4:50, but outlying results are always trickier, I know
fetcheveryone Apr 2013 11:38am, 16 Apr 2013 12,569 posts	0 fetcheveryone The prediction that comes from my spreadsheet turns 1hr58 into 4hrs29 - much closer to what you ran. That's encouraging Well done on knocking half an hour off your marathon time btw
The Teaboy Apr 2013 11:41am, 16 Apr 2013 6,496 posts	0 The Teaboy My experience of time prediction is that the exponent varies from athlete to athlete depending on their natural abilities over shorter or longer distances. I myself being a short distance specialist tend to use 1.09 or even 1.10 to find the best fit.
Ultracat Apr 2013 11:41am, 16 Apr 2013 10,327 posts	0 Ultracat My half PB is 1.58 and marathon is 4.18 I would say double half marathon time plus 20 mins to calculate marathon potential time
Crooked-smile Apr 2013 11:41am, 16 Apr 2013 1,537 posts	0 Crooked-smile Thanks
K5 Gus Apr 2013 11:44am, 16 Apr 2013 86 posts	0 K5 Gus 1:27:50 and 3:12:08
The Teaboy Apr 2013 11:44am, 16 Apr 2013 6,497 posts	0 The Teaboy Note, this time prediction is experience from predicting times over a range of distances, not just HM-Marathon.
Crooked-smile Apr 2013 11:44am, 16 Apr 2013 1,538 posts	0 Crooked-smile And that does seem more accurate- I reckon 4:29 is in my reach just now!