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The RW Race-Time Predictor
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I ran the local weekly free 5km park run and finished in a time of 19.05 well behind my pb of 17.29.I put this in the race time predictor and it said I would take 1 hour 27 minutes and 42 seconds for a Half Marathon.I was a bit disappointed because I originally was planing to make the top 20 in the Cardiff Half the following Sunday.
I decided this about 4 months ago but could not shake off this infection.I figured with the way I had improved since the begining of the year there was no reason I could not go sub 75 by the time it came around.I was 2nd in a 9.5 mile race in June finishing in 55 minutes 40 the race predictor back then suggested 78 minutes for a half.
I went into the race sensibly ,feeling a bit daft with my elite number ranking me 21st doing 6 and a half minute miles and aiming to complete it in 85 minutes, which was a little ambitious considering the computer told me I could only manage just under 88 the week before.
I started to stretch myself towards the end as I felt stronger than the time suggested by the computer and managed to finish in 82 minutes and 52 seconds.I was almost 5 minutes faster than the predicted time!
The lesson here is there are many factors that come into play in a race and a computer cannot predict them all.I hadnt completely got over my chest infection the week before and I took a Hornet Juice on the day which may have helped (sorry about the plug).Also I think I am a lot better at Half Marathons than 5km races.
In response to the core question: "Is the calculator accurate?" Consider this:
The mile world record is 3:43 and this calculates to become 1:58:27 for the marathon. The world record for the marathon is 2:04:59, not far off from the 1:58 calculated a second ago. So this suggests that the calculation hold's water, at least when it comes to the elite athlete's capabilities.
Now in this comparison common sense tells us a couple things. First, we know that having a world record miler run a marathon "green" (no marathon specific training) will NOT result in a ~2 hour marathon. In-fact, it may not even result in a 3 hour marathon (well, maybe so). That's because sprinters fast twitch muscles are more developed than than his slow twitch muscles (for speed). Similarly the marathon record holder if asked to sprint a mile would most certainly not run under 4 minutes. The marathoners slow twitch muscles are more developed than his fast twitch muscles (for endurance).
So considering these are both elite runners, and we believe the calculator to be fairly accurate, one might conclude that if the marathoner trained for speed, focusing on developing fast twitch muscles then he should be able to run a mile very close to WR pace (sub 4 minutes). And similarly, the miler, if training for a WR marathon, might be able to pull off a 2:10 or 2:15 marathon.
This all seems logical enough, but we should factor in some genetic factors. Maybe some people are more predisposed to become sprinters rather than marathoners. So this would suggest that our WR sprinter would not be able to pull off a marathon close to a WR pace. Such genetic factors could include being predisposed to having more of one type of muscle (slow twitch) or having a cardiovascular system or aerobic system which is better for endurance than sprinting.
So what's the truth? Well, I'd say, a little of column A or a little of column B. Both concepts sound plausible, right? If the rules don't apply to you, it's probably either because you're A) genetically predisposed to run either with speed or with endurance OR
you've been training more for either speed or endurance OR C) both A and B. So I say, use the calculator as a guide of what you are capable of, assuming you train properly for the distance which you are trying to calculate the time for.
-B
I put in my 5k time of 18:58 and it gave me a projected 10k of 39:34... two weeks later I ran 39:34!! FREAKY!!
Word of warning it does assume you have trained for the type of race it is predicting so 10k runners who's half time is slower will be down to a lack of focused training and the endurance needed to run a half. Only use it to predict the next distance up or down. Using a 10k to predict a marathon time is pointless.
The little piece by Brian Cox...do you really think 6 1/2mins over half marathon is "not far off"?
That's a hell of a distance off!
Why not use the same formula for the 100m record? That'd probably bring the marathon equivalent out as 1hr 40 or something...madness, and pointless, no disrespect
Back on the original thread subject, for probably the only time ever, my 5k and half times match to the second!!
But bizarrely the ones in the middle don't!
I tweaked the formula for my own PRs, and got to the following:
T2 = T1 x (D2/D1)^1.20
If I read the comments above, most people agree with me that the distance exponent is larger than Pete Riegel's formula suggests. It would be nice if it would be possible to change this by hand in the race time predictor.
Bryan (Ewok's Mate) would have a factor of 1.125
Urban Road Runner 1.135
for 10k it predicts 50 minutes, which is 3 minutes slower than my last time.
I used this to predict my 10k time based off my 5k. At first I was skeptical, thinking it was predicting faster than what I would do, but I actually ended up running faster than the prediction. Based off my 20:39 5k, I was to run just over a 43:00. I ended up running a 42:50 (this could have been a fluke, beginners-luck thing. It was only my second 10k of my life). In terms of per mile pace it was only like a second or so off, which I think is pretty darn good!
Might the predictor require some tuning ?
If I enter 21.0975 (half a marathon) and 1:20:10, the reply for 42.195 is 02:47:08.
According to the explanative text, I would have expected (1:20:10)*2*1.06 = 2:49:57?
The answer 2:47:08 looks like the coefficient would have been 1.0455 instead of 1.06?
(cancel and replace) oops, I missed the point! The formula is (^power)1,06 and not (*multiplied by)1,06.
What FrdricLN said, the formula is good, but it is stated incorrectly, it is to the power of 1.06, not multiplied by it as stated.
congratulations for clearing up a 8 month mystery!
So, I have done 19.5 miles in 3hrs 16 and this says my marathon will be 4hrs 28 ?
Having done almost 20 miles in approx. 3hrs 15 it will suddenly take me 1hr 12 to do 7 miles?
I doubt it!
Why do you doubt it? You want to do a third more distance (26.2/19.5=1.34) so if you didn't tire whatsoever and ran a flat pace you'd need another 1:05. You get the same answer if you feed the expression into google search bar, i.e.:
196 * (26.2/19.5)^1.06=
i.e., 268 minutes or 4:28. So the calculator is working. The exponent varies a bit from person to person.