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A runner in Israel, Hanan Joseph, sent to me a copy of two articles that he published
on an Israeli website analyzing the relationship between the results of runners who completed both a half marathon and a marathon
that are run four weeks apart (December and January) in Israel. The first article (Part I) is based on the results of the
2007-2008 races. The second article (Part II) reflects data from the 2008-2009 races. A translation of the articles, which
were originally written and published in Hebrew, are posted here with Hanan’s permission.
Hanan’s articles complement and expand on two previous essays posted on my Running
Page (Predicting A Marathon Time and Half Marathon Pace vs. Marathon Pace) that address actual marathon vs.
shorter distance race performances compared to projections by popular running calculators. His interesting
analyses of (1) the relationship between marathon and half marathon results of approximately 600 finishers grouped into seven
marathon finishing time categories and (2) the quality of marathon pacing (within 4% of even splits) in each of the seven
categories add additional dimensions to the subject.
Predicting Marathon result based
on Half Marathon
result. – Part I
Written By: Hanan Joseph. Edited by: Moshe Bretter
Introduction:
In Israel, there are two main running events. Beit-Shean Half marathon and 4 weeks
later Tiberias marathon. Both races have similar courses and weather conditions. After the HM, most runners, before even taking
a shower, will check their estimated marathon result based on McMilan's calculator.
McMillan's calculator evaluates the ratio between the HM
result and the marathon result as 2.11, e.g. 1:45:00 HM result is predicted to be 3:41 at the Marathon.
I tried to validate this ratio, based on the results of 348 runners who participated
both the Beit-Shean HM and Tiberias marathon in 2008.
Test Method:
- Calculating Net time
- Calculating the ratio between HM and Marathon results
- Calculating half way point at the
marathon (21.1 km)
- Cleaning the data from unreasonable
results, like ratio less than 2 (No connection between HM and Marathon) and ratio bigger
the 2.5, runner had serious difficulty completing the marathon.
- Dividing Marathon
results into time categories.
Ratio Results by Categories:
|
No. of Results |
Marathon / HM Ratio |
Categories by Marathon result |
|
31 |
2.12 |
Sub 3:00 |
|
29 |
2.14 |
3:00 to 3:15 |
|
68 |
2.17 |
3:15 to 3:30 |
|
53 |
2.2 |
3:30 to 3:45 |
|
44 |
2.2 |
3:45 to 4:00 |
|
33 |
2.22 |
4:00 to 4:30 |
|
19 |
2.29 |
Over 4:30 |
Ratio Results by Categories - Graph:
We can clearly see that the faster the runner is the ratio is smaller.
The next step in my experiment was to check how well the runner planned his run. I defined a metric which I called "Good
Run".
"Good run" is a reasonable ratio between HM and marathon, and running even splits.
- Reasonable marathon ratio – The runner's ratio is around the category average, meaning not too conservative or too
pretentious, e.g. for 3:15 to 3:30 runners the reasonable ratio is between 2.1 to 2.22 (AVG is 2.17). The lower end of the
range is the McMillan prediction and the upper end is the average ratio plus 2%.
- Even Split – The ratio between halfway mark and
final result is between 1.96 and 2.04. Ratio equals 2.00 – perfect splits, bigger than 2.04- runner hit the "wall",
less than 1.96 starting too slow.
- Exceptions – I consider "good run" for those
runners who had ratio less then lower limit but had "Even split".
"Good runs" analysis:
|
"Good Run" % |
Even Split % |
In Range % |
Ratio Range |
Marathon / HM Ratio |
Categories
by Marathon result |
|
90% |
90% |
68% |
2.09-2.15 |
2.12 |
Sub
3:00 |
|
69% |
79% |
62% |
2.1-2.18 |
2.14 |
3:00 to 3:15 |
|
62% |
69% |
68% |
2.1-2.22 |
2.17 |
3:15 to 3:30 |
|
53% |
53% |
77% |
2.1-2.25 |
2.2 |
3:30 to 3:45 |
|
36% |
41% |
66% |
2.1-2.25 |
2.2 |
3:45 to 4:00 |
|
24% |
33% |
67% |
2.1–2.27 |
2.22 |
4:00 to 4:30 |
|
11% |
11% |
58% |
2.1-2.35 |
2.29 |
Over
4:30 |
Graph:
Results Analysis:
- I find McMillan basic assumption, that the ratio between
HM and marathon results is a constant, has no validity. There is a changing ratio, depending on the runner's ability. In my
opinion slower runners have insufficient aerobic fitness to handle the progress from HM to marathon.
- We can clearly see that slow runners have less "even
splits". This means slow runners start too fast for their ability.
- There is a significant difference between runners with
marathon result up to 3:30 and those over 3:30. It seems that running a marathon requires the ability to practice
runs at a faster pace.
- Running the desired negative split is very difficult,
and seems a little bit unrealistic for slower runners (over 3:30)
- We can assume that slower runners tend to be less experienced,
therefore they make more pacing mistakes.
Recommendations:
- Based on the results it seems a runner should evaluate
his marathon pace based on his desired category and not by McMillan's calculator evaluation.
- The less experience the runner is, he should be more
conservative regarding his marathon pace.
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Predicting Marathon result based
on Half Marathon
result. – Part II
Introduction:
Part I of the article checked the ratio between 2008 half marathon and Marathon results.
I claimed the assumption that the ratio between HM and Marathon is a constant (according
to different calculators) isn't valid.
I made an additional check based on 2009 Tiberias marathon and Beit-Shean HM (occurred 4 weeks earlier).
Test Method:
Based on Marathon result, marathon splits and HM result I calculated
the following ratios:
- Actual Ratio – Marathon
result divided by HM result
- "Half" Ratio – what suppose to be the runner's
marathon result based on his half point split, divided by HM result
- 30 KM (18.75 mile)
Ratio - what suppose to be the runner's marathon result based on his 30 km point split, divided by HM result
- Clearing data of ratio bigger than 2.5
Ratio Result by Categories:
|
Time loss per 7.45 mile
[minutes] |
Pace loss [sec/mile] |
30 KM Ratio |
"Half" Ratio |
Actual Ratio |
No. of Results |
Categories by Marathon result |
|
1:00 |
8 |
2.10 |
2.10 |
2.14 |
28 |
Sub 3:00 |
|
0:48 |
6.5 |
2.14 |
2.12 |
2.17 |
37 |
3:00
to 3:15 |
|
1:12 |
10 |
2.14 |
2.12 |
2.18 |
56 |
3:15 to 3:30 |
|
1:48 |
14.5 |
2.16 |
2.16 |
2.22 |
54 |
3:30 to 3:45 |
|
3:48 |
31 |
2.13 |
2.13 |
2.25 |
57 |
3:45 to 4:00 |
|
3:36 |
30 |
2.20 |
2.17 |
2.31 |
42 |
4:00 to 4:15 |
|
6:00 |
48 |
2.16 |
2.15 |
2.33 |
30 |
4:15 to 4:45 |
|
6:48 |
55 |
2.20 |
2.14 |
2.38 |
12 |
Over 4:45 |
Pace loss – evaluation of how many seconds per mile the runner has slowed down in the
last 7.45 mile.
Time loss – how
many minutes the runner lost due to slowing down
Results Analysis:
- Once again, we can clearly see that the ratio between
marathon result and HM result isn't a constant, but a variable according to the runner's level.
- Until the half distance point, most runners were able
to stay near the McMillan's ratio (2.10 to 2.17)
- Some of the runners started slowing down from half
distance point. The difference between yellow line and the pink line. Between 13.1 mile mark and 18 mile mark, runners slowed down a bit.
- Runners started to hit "the wall" from the 18 mile
mark.
- 3:30 hours runners, lost about 8 sec/mile
- 3:45 to 4:15 runners lost about 30 sec/mile
- Over 4:15 runners lost about 50 sec/mile
- We can see that most runners can run at McMillan's
predicted pace until 18
mile mark.
- The slower the runner is, the ratio gets bigger, meaning
unwanted positive split.
Recommendations:
- The recommendations from part I are still valid, chose
your category ratio and chose conservative pace.
- It's better to start slowly and keep the pace until
18 mile mark
Most runners eventually will hit "the wall", therefore be prepare for that during your marathon
run and during training.
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