53 replies to this topic

[jockster]

Ok, while there are many articles on BMI & ideal running weight etc.  I thought it would be an interesting discussion to see if there is a relationship amongst elite's and mere mortals over say 10k.  I've noticed my time come down almost proportionately to my weight.

Body Mass Index = Weight in KGs / (Height in metres squared)

eg. Me current, 55kg / (1.58m x 1.58m) = 22.03

My best times over 10k and my BMI:

BMI : Time

26.04 : 43.35

24.03 : 39.40  (From prior PB thats a 7.7% decrease in BMI and 8.8% decrease in time)

22.03 : 38.17  (From prior PB thats a 8.3% decrease in BMI and 3.4% decrease in time)

I would think for an elite athlete that given the same BMI they would run significantly faster than a mere mortal such as myself.

What are peoples BMI and there best times over 10k?

[miners]

Interesting topic jockster.  What's even more interesting is that my current BMI and 10km PB virtually match the second step along your progressive weight loss.

BMI : Time

23.87 : 39.35

Wonder if that 0.17 difference in BMI really explains those 5 seconds?

[ashrun]

18 : 32:57

[Gasher]

BMI  :  Time
26.02   45.56

[Rudolf]

mine currently: 21.22 10k guestimate 55-57min

Craig Mottram = 71kg 188cm = 20.09

So I could clearly not see any correlation here.

My personal explanation is this - Could not compare between people, if You follow Your progress, what is happening, You keep the same hight and basically the same muscle mass, and You losing fat. As You drop off each kilo of fat, You run faster, like You drop off extra weight from Your backpack.
Or from other view - as You train Your endurance
and do lot of aerobic training ( You of course improve Your 10k) but You also learn how to burn the fat and You actually burn it off as You progrees. So 10k time are faster, and Your body mass reflects the fat lost.

[marathoner]

My BMI is 17.9 and my best time over 10km is 42:20.

BMI: 17.8
10 KM TIME: 42:20

[seagull]

24.3 : 39.22  - PB (2000)
25.5 : 41.24  - Recent (Season best)
29.0 : 52.14  - October 2004
26.8 : 46.54  - May 2004

My 10km race times and weight correlate strongly.
My training also correlates with both!
(Not a big surprise!)

On the cause and effect front, I have had a sneaky suspician for a while that weight contributes almost as much as a factor as training does to my improvement or deterioration in performance.

I would be very intrigued to see a large sample of BMI versus 10km time.

[Jonesy]

22.9: about 38:00 at present

[FakePlasticTrees]

25.3 : 42:15

[Johnny Dark]

BMI : 21.2

Time : 44:08


JD

[seagull]

26.04 : 43.35 - jockster
24.03 : 39.40 - jockster
22.03 : 38.17 - jockster
23.87 : 39.35 - minersrun
18    : 32.57 - ashrun
26.02 : 45.56 - Gasher
21.22 : 56.00 - Rudolf
17.9  : 42.20 - marathoner
24.3  : 39.22 - seagull
25.5  : 41.24 - seagull
29.0  : 52.14 - seagull
26.8  : 46.54 - seagull
22.9  : 38.00 - Jonesy
25.3  : 42.15 - gnscon
21.2  : 44.08 - Johnny Dark
24.16 : 38.22 - Puntermatt
24.6  : 39.47 - melb_runner

--- Sorted into BMI bands -----
--- Fatest to slowest for each BMI integer ---

17.9  : 42.20 - marathoner

18    : 32.57 - ashrun

21.2  : 44:08 - Johnny Dark
21.22 : 56.00 - Rudolf

22.9  : 38.00 - Jonesy
22.03 : 38.17 - jockster

23.87 : 39.35 - minersrun

24.16 : 38.22 - Puntermatt
24.3  : 39.22 - seagull
24.03 : 39.40 - jockster
24.6  : 39.47 - melb_runner

25.5  : 41.24 - seagull
25.3  : 42.15 - gnscon

26.04 : 43.35 - jockster
26.02 : 45.56 - Gasher
26.8  : 46.54 - seagull

29.0  : 52.14 - seagull

I reckon with enough data points the lower the BMI the faster the fastest time - At least down to
a BMI of 20, probably down to a BMI of 18.

[Puntermatt]

Gees Jonesy, you have a better BMI than my 24.16(all muscle of course)  :rolleyes:  

Anyway, I'm 1.82 and 80kg and still carry a fair bit of bulk from many years in the gym.

Currently have a soft PB of 38:22 to go with that 24.16 BMI.

Want to go low 30's for the 10k within five years so it sounds like a BMI of around 22 and a weight of around 75 is required.

PM

[Colac]

Great set of stats, intriguing way to look at it.
I guess the question is, "how do you identify the best BMI for an individual?"

[melb_runner]

24.6  :  39:47

[antipop]

So what weight should I be aiming at to improve my times, I currently weigh 87.9kg and I am 6'1'.
I currently run 8 km in 36.30. Is it possible to run under 34min if I shed more kilos or has it got to do with increasing my speed work?
By the way, i'm trying to get my weight down to 83kg  ;)

[Peterhorse]

In my science training at Uni, our biometrics lecturer drummed into us that "correlation does not mean causation". That is, you can observe associations between things but that doesn't necessarily mean one causes the other, just that they are tied together somehow. If low BMI was the cause of lower 10k times for example, we could use the data and a regression equation to forecast 10k times. Or the other way around (by swapping the BMI to the dependent variable) in which case we could predict BMI off 10k times. Clearly these is correlation, but my instinct says they won't be a great predicitor of each except in a tight range. As Colac says, it is more likely you could do predictions on yourself only - like Jockster has done...

E.g. in my case at 188cm (same height as Craig Mottram), 85kgs and 10k PB of 45:54, if i lost 14kg, i am unlikely to have a PB like craig Mottram's, but i might have a much lower PB relative to my starting point?

I'd be happy to crunch some numbers on this and see what they say, I've got Jockster's data and those above, so if more CR's add in their height, weight and 10k times, i can take it from there...i'll leave it run for a few weeks and see what data we have. (i'm not a sports scientist by the way)

Cheers
PH

p.s. Jockster ran a TOP marathon in Toowoomba recently...great stuff mate!!

[Colin]

I think it is pretty clear that Jockster was interested in BMI v performance for individuals , rather than correlating across all athletes.

If a person decreases their own BMI, then it will follow that (providing its not accompanied by loss of power), the energy cost to move the centre of mass will be less.

The way it will affect different people is also influenced by morphology (limb length v torso).
Longer limbed runners use less energy to move their centre of mass, but incur a higher energy cost in moving the limbs.

More on that at Predicting locomotor cost from linb length via force production

btw my BMI vs 10km as follows

19.8/32:30 (1985)
21.3/34:30 (1990)
21.7/38:00 (2000)
23.0/40:00 (2005)

However, the effect of aging and amount of training should also be included, making this sort of predictor very difficult.

[John Dawlings]

My BMI has hovered around 21 for some years now (height of 173 and weight of around 63).  PB for 10 kms is 33.08 but am currently running about 36.30.  The variation in times with the same BMI is due to ageing in my case.

[Virtual]

25.4  <_<  / 45min  <_<  / 43yo   :)

[Fish]

24.12, 38:37, 35 yo

[MPHinLondon]

BMI 23.1 10K 35:19 Age 29

[Miss Gazelle]

BMI = 19.8
10K = 47m
Height = 164cm

[seagull]

26.04 : 43.35 - jockster
24.03 : 39.40 - jockster
22.03 : 38.17 - jockster
23.87 : 39.35 - minersrun
18 : 32.57 - ashrun
26.02 : 45.56 - Gasher
21.22 : 56.00 - Rudolf
17.9 : 42.20 - marathoner
24.3 : 39.22 - seagull
25.5 : 41.24 - seagull
29.0 : 52.14 - seagull
26.8 : 46.54 - seagull
22.9 : 38.00 - Jonesy
25.3 : 42.15 - gnscon
21.2 : 44.08 - Johnny Dark
24.16 : 38.22 - Puntermatt
24.6 : 39.47 - melb_runner
19.8 : 32.30 - Colin
21.3 : 34.30 - Colin
21.7 : 38.00 - Colin
23.0 : 40.00 - Colin
21 : 33.08 - John Dawlings
25.4 : 45 (43) - Virtual Runner
24.12 : 38:37 (35) - Fish
23.1 : 35:19 (29) - MPHaz
19.8 : 47 - Myrtle the Turtle

--- Sorted into BMI bands -----
--- Fatest to slowest for each BMI integer ---

17.9 : 42.20 - marathoner

18 : 32.57 - ashrun

19.8 : 32.30 - Colin
19.8 : 47 - Myrtle the Turtle

21 : 33.08 - John Dawlings
21.3 : 34.30 - Colin
21.7 : 38.00 - Colin
21.2 : 44:08 - Johnny Dark
21.22 : 56.00 - Rudolf

22.9 : 38.00 - Jonesy
22.03 : 38.17 - jockster

23.1 : 35:19 (29) - MPHaz
23.87 : 39.35 - minersrun
23.0 : 40.00 - Colin

24.16 : 38.22 - Puntermatt
24.12 : 38:37 (35) - Fish
24.3 : 39.22 - seagull
24.03 : 39.40 - jockster
24.6 : 39.47 - melb_runner


25.5 : 41.24 - seagull
25.3 : 42.15 - gnscon
25.4 : 45 (43)- Virtual Runner

26.04 : 43.35 - jockster
26.02 : 45.56 - Gasher
26.8 : 46.54 - seagull

29.0 : 52.14 - seagull

[FlyerUltra]

1997 (36 yrs old) : BMI 22.9, 10K 38:02
2005 (44 years old): BMI 21.2, 10K 36:49

[Rudolf]

antipop

[QUOTE]Originally posted by antipop:
[QB] So what weight should I be aiming at to improve my times, I currently weigh 87.9kg and I am 6'1'.

to simply answer Your question :
elite runners have BMI under 22, Mortram around 21 and lots of them would be 20 or less -
just talking about males here.
Sio Your target weight can be such which gives You BMI 22, sorry I am not familiar with foot and inches, You have to do calculations for Yourself.

The point is that long term proper earobic training will take care not only about Your
10k perfomance but more importantly of Your
unwanted body fat.
I did other way around, using detox and nutrition to get down to 22 BMI (71.5kg - 63/65kg) and then only started jogging and crosstraining 4 months ago, hence my slow 10k.
It just illustrates the point made by others and myself above, that statistical correlations could be very missleading and is often missuesed to prove anything. The cause and effect is ussually completelly different story.

[charlieboy]

Fat and fit is better than thin and unfit

BMI: 27.2
10k: 39.0

[Rudolf]

I just had this idea :
for thouse who carry more weight than they wish :
(the idea is from Biggest looser TV story, when they froced them to run with the added weight equal to the weight lost in the previous months).
Say You feel You cary 5 , 10 or more kg of nonfunctional weight (lets call it fat), and are wondering how much faster You would run if You loose it. Test it the other way around.
Put on some type of extra weight equal to the weight You would like to loose (5, 10,...).
Use backpack, diving west, weight training west,
hold weights, whatever.
Run the distance as a time trial.
If Your 10k PB is 40, and with added weight is
(42, 45,...) than perhaps good guestimation would be that running after weigt loss will give the same improvement.
With change or increase in training.
I lost 5 kg within 3 months of nutritional detox
with no exercise at all.

[jockster]

Some very interesting results. Nice work Seagull on giving some good comparitives that is easy to read.

What I wanted to see is if BMI could be used as a 'general' indicator of one's potential speed.

There are quite a few similar groupings.  Not surprisingly there are a few outliers, which you would expect. The BMI group of 21 has quite a large range in it.  Probably a little wider than what I would have thought.

How long have "Marathoner"/"Rudolf"/"Johnny Dark"/"Myrtle the Turtle" been running for? Potentially the results indicate they should be running sub 40.  Other than these, all the other results are fairly similar give or take.

Antipop - Currently your BMI is approx. 25.7 which indicates a current 10k time of around 43-45min. If you can get down to your 83kg that you are aiming for, your BMI would then be 24.3 and an equivalent 10k time of around 39-40.

Ignoring everyone's training schedules, perhaps BMI alone may indicate one's potential time.  I would suggest then a 'good' training program will only relatively improve a persons PB on a stable BMI.  ie. A person having a stable BMI will only marginally increase their PB 'relative' to those others who have the same BMI on shall we say an inferior training program.

As I am currently experiencing, my BMI has lowered over the last year, where I have seen significant gains in my PB.  So perhaps the one thing my training has done is to lose excess body fat. And this is the main reason for my faster times.  

If more people can post their BMI and 10k PB, Peterhorse can crunch the numbers, to see if there is a strong correlation.  I agree that a low BMI probably doesn't cause a low 10k time, but it does give an approximate guide as to the potential time give or take a minute or so.

Good work everybody!
cheers

[Tubby]

23.7BMI  39.04

[MaxMTC]

Earlier this year i had a bit of an experience that seems to be the opposite to what most people have indicated.  At the end of last year my BMI was 21.5.  There is a course i do time-trials on regularly, and prior to that my pb over it was 21.02, and i had run within about 10sec of this mark a number of times in the two or three months prior.  Over the summer i changed my training...more kms, but speed work sessions were shorter and sharper.  I ended up gaining about 3kg, i think mostly through improved leg strength, which took me up about 1 point on the BMI scale.  Over this time my best time for that course reduced to 20.19.

Edit: Its not a 10km course that i am referring to!

[Rudolf]

Jockster -
You asked for additional info :
well my jogging only started about 4 months ago, and at the time I could only jog at 10min/km
for short time, only about 3 months ago I managed to run 10k in 90 min, currently am at around 55-57
12k in Coburg = 69:45
5kCRwobble = 27:22
so I am close to 5:30min/km pace for 10k.
Still just doing slow runs, strictly aerobic, thouse 2 races were the only times I did anything lactic, no speed sessions,...
If You keep this thread active, I would keep adding my improvements.
20 years ago, I was around 36-37 min 10k runner
on mainly lactic training, which resulted in 2 decades of ilneesses injuries and chronic fatique.
That time my weight in years was in 60-65kg range
and I was under 40 min 10k for nearly a decade.
So I am buggering Your statistic for the moment, but I promisse I will fit in better next year.
Realistically, I can loose about 2kg of fat, but because of my crosstraing, muscless are groving,
so I would not get under 63kg.
However, I wish I could loose about 30 min of my 10k time, but am not going to take any lactic shortcuts.

[Rudolf]

MaxMTC - as You go shorter the distance, the correlation changes and reverse, just take the extreme - 100m, where the bigger BMI is preferable.
I am going to offer my personal opinion, what might be (but I could be wrong here) Your situation.
Just assume You course is 5-6 kms or so.
If You do lot of lactic tolerance training, Your performance at 5 km clearly improves short time.
That is clear. Lactic tolerance effect (I am using my studies of bodybuilding here) can cause
buildup of lactic byproducts in the muscless in the in between fibres area, sometimes referde to as swolen muscless, or other names used, suggesting, it is not pure muscle fibres representing the muscle size and mass here, and is trade off for high definition hard muscless
of smaller size.
This is toxins like storage proces.
Ohter proces is effect of increased muscle glycogen, which is usefull for running and all other muscle actvity.
So You increased Your BMI, because whatever happened to Your muscless (good or bad) as a result of speed and/or lactic tolerance training.
Just womdering if You got the same improvement for 10k distance ?

[MaxMTC]

The course that my time trials were over is a bit short of 6km.  I don't really do a lot of 10km races (only 4 this year, 4 the year before), so it gets a bit harder to compare, and I didn't have any 10km results to compare during that period.  Before the change in training i was running about 37~38min for a flat 10km road coarse.  Early in the year i ran 36.5min on what is also a flat course.

[Tan Man]

Height 1.80 meters
Weight   80 kg
BMI      24.69
10KM PB 35 minutes

[2Hefty]

Height 1.88 meters
Weight 93 kg
BMI 26.3
10KM PB 44 minutes

[seagull]

Peterhorse have you crunched the numbers yet? or still waiting for more data points to flood in?

[RodN]

The numbers seem to look consistent from the high BMIs down to about 23 then from 23 to 17/18 they lose the plot a bit.

I think perhaps what would be more interesting is to consider whether it's the BMI that causes the fast run, or the fast run leadup that causes the BMI.  It could be that runners with lower BMI have that because they are training to be fast, rather than the other way around.

edit: woops noticed how OLD this discussion was!

Edited by RodN, 28 April 2009 - 09:53 AM.

[bruncle]

Interesting thread. Thanks for bumping it up.

There's a rough figure that every kg of unnecessary body weight will cost you 2.5 seconds per km (don't ask me for a citation, I got if off an American site which gave a lb/mile figure). I'm trying to lose about 10kg (aiming for BMI of 18.5, current 22ish) to exploit this. Interestingly, when I used to weigh 60kg (BMI 20ish), I was running a fair bit slower than I was now. Pretty sure that I'm running faster now in spite of, rather than because of the weight gain.

[moby]

There is a spreadsheet available to download on the internet called the Daniels Tables (http://www.electricb...lsTables2-9.zip) into which you plug a race time and distance as well as your weight and height.  Along with recommended training intensities and predictions of performances at other distances it also provides an estimate of the effects of temperature and weight on performance.

The calculation in this spreadsheet estimates that in a 10km race every kg of weight adds or subtracts about 29 secs from my time (so about 3 secs per km) so long as I stay in the healthy weight range for my height.

I’ve also recently read something else about this from US coach Tinman who said the following:

Quote

Since body weight and relative VO2 cost are inherently linked, any percent change in body weight, up or down, should theoretically affect change of pace similarly. For example, a 3% change in body weight should result in a 3% change in relative VO2 cost and hence a 3% improvement in velocity.

Example: Ken runs 6 minutes per mile at VO2 max. He drops 3% in body weight. His predicted pace per mile at VO2 max moves to 5:49.51 per mile, which is 3% less total time per mile.

Caveat: the time-course of adjustment to percent of body weight change relative to percent change in running velocity may be different. Thus, Ken could lower his body weight by 3% in a month, but it may take 2 months to realize a 3% improvement in running velocity; it may not, either.

[Peterhorse]

seagull, on Apr 28 2009, 08:35 AM, said:

Peterhorse have you crunched the numbers yet? or still waiting for more data points to flood in?

Not crunched yet my apologies. i will try to do so on the weekend.

[falknis]

Height 1.80 metres
Weight 67kg's
BMI =20.6
10km PB 36:50

[akajan]

Height: 1.75m
Weight: 60kg
BMI: 19.6
10k PB: 29:42

[blair]

Peterhorse, on May 8 2009, 10:43 AM, said:

Not crunched yet my apologies. i will try to do so on the weekend.

Geez Pete, you've only had 3.5 years

[walker1st]

balri, on May 8 2009, 04:39 PM, said:

Geez Pete, you've only had 3.5 years

yes, but he has to feed the horse every day and run the horse every day

[FlyerUltra]

BMI: 20.4; 10K time about 36:15- I suggest probably limited by leg turnover rather than BMI or aerobic capacity.

[Studebaker]

Thought I would throw in a curly one, by being outside normal height:

Height 2m
Weight 95kg
BMI 23.75
Best 10k time 46.30

Have not run a 10k race since Nov 2007

[julia]

moby, on May 8 2009, 10:17 AM, said:

There is a spreadsheet available to download on the internet called the Daniels Tables (http://www.electricb...lsTables2-9.zip) into which you plug a race time and distance as well as your weight and height.  Along with recommended training intensities and predictions of performances at other distances it also provides an estimate of the effects of temperature and weight on performance.

Thanks for that link! That spreadsheet is really interesting! I like the amount of input you can put into it and the amount of information it gives.
I like the guidelines it's giving about temperature and weight. Definately supports why I find running easier in winter and how I find it easier to race when I'm lighter. It provides some really interesting predictions!

As far as weight height ratio vs time - I do run faster when my BMI is lighter, but I think that has a lot to do with the fact that for my BMI to get lower I need to increase training - so I would assume I would run faster with the increase of training and endurance I've developed.

[bruncle]

I think there may be a teensy bit of sampling bias in this data. Looking at it, there are only 2 times over 50 minutes. Hardly reflective of either the CR community or the running community as a whole. Ignoring this, I stuck the data into the R statistical package and came out with the following results:


As you can see from the very scattered data points, there is not a very good relationship between BMI and ten km PB (R-squared = 0.22). The regression equation is TenKTime = 1.05xBMI + 16.2043

The CSV file with the data people submitted is attached.

As other people have suggested, this kind of thing has very limited predictive value. There is a general positive trend to the data (higher BMI = higher ten k time), but beyond that, there is far too much scatter from individual variation to have any firm conclusions. I'd be interested to see if the scatter would iron itself out if we collected more data. I might hack together a shoddy PHP script to do exactly that.

Attached Files

•  bmidata.txt   643bytes   1 downloads
•  bmidata.png   4.18K   5 downloads

[AndrewFF53]

Great thread!

I was thinking about this on my run this morning. I have recently started running into the city with a back pack full of a change of clothes note books and a few other essentials for the day. I have not weighed the pack put it feels as though it is getting close to 10kg. I try to run at a base pace effort which at the moment, without a back pack is around 5:15min/km however when I have the back pack on for the same perceived effort I am running about 5:30 to 5:45 pace.

Hence I was wondering what I sort of reduction in pace I should expect when running with a pack, note I am not talking race pace here I am talking a slightly more relaxed pace, this thread has given me a bit of data to work with. The 2.5sec for every 1kg does seem to be in the ball park!

I have a few other projects on at the moment, but I was thinking of loading the pack so it is 5kg then 10kg and running a set loop at a range of perceived efforts then plotting heart rate on the x-axis (as a measure of effort) and on the y-axis pace.

Does anyone else how runs with a backpack have an observation as to how there pace is effected by the weight of the back pack?

If I include my back pack weight in my BMI then my BMI goes from 21.87 without a pack to 25.46 with a pack.

[2feetoffground]

Body fat is one thing - losing unnecessary muscle mass accumulated in the gym before the distance running bug struck is different matter with possibly the same solution - lots of miles and lots of long runs? However it is rather stubborn!