Working out next targets
I've now completed two weeks of my post-marathon recovery and have only fifty weeks to go until the VLM
. Now is the time to review my stats and flesh-out my targets for the forthcoming campaign. As I've already said, I'm hoping to reach 3:45 for the marathon next year – but what does this mean for my more immediate training and targets? Like most people I turn to the online race predictors to work out what I must achieve at other race distances. But before I place my faith in the results, it makes sense to review how well they have predicted my previous results.
Starting with the Runner's World Race Time Predictor. This calculator uses the Riegel formula:
T2 = T1 x (D2/D1)1.06
where T1 is the given time, D1 is the given distance, D2 is the distance to predict a time for, and T2 is the calculated time for D2.
According to Runner's World 4:00 Garmin Schedule, I needed to achieve a half-marathon time of 1:50:00 to be able to run a sub-4 hour marathon. This also tied-in with other calculators and tables that I researched. Using this calculator, I had predicted targets of 49:54 for the 10K, 23:56 for the 5K and most importantly 3:49:20 for the marathon.
My results were 23:32 for 5K, 49:55 for 10K and 1:50:04 for the half-marathon. So that was an impressive thumbs-up for the calculator. On that basis, it should have been a shoe-in to get a sub-4 marathon. However, the actual result of 4:09:29 was apparently sub-par. Indeed, my marathon result has always fallen short of expectations based on results at shorter distances. Last year my half marathon time of 2:01:34 predicted a marathon in 4:13:27, but I dragged my arse home in 4:38:54. So on the face of it, the calculator is great for races up to half-marathon, but way too optimistic for the marathon. All of which has left me in a bit of a quandry about how to set targets for my next marathon, since my results are clearly out of kilter.
Last week I received an email containing an article by Ian Williams at fetcheveryone.com about marathon time prediction. Here are some condensed extracts:
“Take a look back at the (Riegel) formula. The 1.06 is important - it represents the rate at which we slow down as the races we run get longer. I fed all of my 1071 runners through that formula, and found that only 49 of them managed to hold on to the tails of 1.06 - it was far more common to see a score of 1.15. We know that faster runners tend to be capable of holding on to their pace for longer. So instead of using a constant 1.15, let's connect that number to the speed of the runner, using their half marathon time. I also looked at the differences between male and female performances. Taking these factors on board, I've built a new calculator that will predict your marathon time based on your half marathon. It should predict your time to within 5% in 77 out of a hundred cases.”
The full article can be viewed here.
Plugging in my most recent half-marathon vs marathon results into this new calculator gave:
2012 Half Marathon 2:01:34 predicted 4:39:04, against my actual 4:38:54
2013 Half Marathon 1:50:04 predicted 4:09:16, against my actual 4:09:29
Pretty outstanding predictions! The bad news for me is that to achieve a 3:45 marathon time, this calculation means that I need to achieve a half marathon in 1:40:29, rather than 1:45:00 that Runner's World suggests in it's Garmin training plan. Nonetheless, I have more faith in the quicker half time.
(continued.....)
Edited: 28/04/2013 at 19:02