What limits 5k/10k speed?

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jamix
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Re: What limits 5k/10k speed?

Postby jamix » Mon Aug 12, 2013 1:32 pm

MichaelMc wrote:
jamix wrote:"Lack of oxygen" is a limiting factor for Elites and non-Elites and even for "non-highly trained / non-Elites" runners alike! VO2max peaks relatively early in the progression of a developing athletes (and actually doesn't increase that much at all in some people). Personally I feel like I've hit that bar years ago.


That is a circular argument. You are assuming oxygen is the issue, and it isn't. VO2 max is NOT a good indicator of who will win a race, so it isn't "the limiting factor". Next, what VO2 max measures is how much oxygen you are able to USE, not how much you are able to get into your system. Availability is not the issue, hence oxygen is not the limit.


VO2max might not predict the actual winner in a field of elites with narrow pb ranges, but it's a great predictor of performances over a larger range and I imagine you'll almost never see a 20-min 5km runner having a VO2max higher than say a 15-min 5km runner.

As for the whole SUPPLY vs DEMAND debate, with regards to what limits VO2max, it has been found that oxygen supply is the limiting factor in most cases;

http://en.wikipedia.org/wiki/VO2_max#Fa ... ng_VO2_max

The factors affecting VO2 are often divided into supply and demand factors.[17] Supply is the transport of oxygen from the lungs to the mitochondria (including lung diffusion, stroke volume, blood volume, and capillary density of the skeletal muscle) while demand is the rate at which the mitochondria can reduce oxygen in the process of oxidative phosphorylation.[17] Of these, the supply factor is often considered to be the limiting one.[17][18] However, it has also been argued that while trained subjects probably are supply limited, untrained subjects can indeed have a demand limitation


There can be Demand limitations too, but only in the untrained; And you certainly don't need to be an elite / highly trained athlete to become Supply limited.
2013 GOALS:

- Compete in the "Early Bird Sprint Triathlon" in May
- Run a 5km pb during the "Bushtukah Canada Day Road Race"
- Complete an Olympic distance triathlon
- Cycle > 33 km / hr during the cycle portion of a Sprint Triathlon.
- Stay healthy and happy

Races

April 28th: Manotick 10km (40:16)
May 18th: Ottawa Early Bird Sprint Triathlon (DNF)
June 8th: Riverkeeper SuperSprint (2nd overall)
July 1st: Bushtukah Canada Day 5km (18:37)

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Jogger Barbie
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Re: What limits 5k/10k speed?

Postby Jogger Barbie » Wed Aug 14, 2013 2:40 pm

ian wrote:
Joe Dwarf wrote:Really, I should weigh 144 lbs at 6' tall? Weight is not linear with height.

Engineering 101: every nonlinear relationship looks linear over a narrow range. In this case, for elite runners between about 5 and 6 feet tall, the simplified formula probably gets it right for most of them (e.g., Rob Watson is 6'3" and races at 150 pounds). The formula has no bearing elsewhere, be it for non-elite runners like us or for those outside the narrow range (e.g., a newborn 20 inches long should weigh 40 pounds).

I think that narrow range starts somewhere above 5 feet, and applies to male elite runners only.

My sub-average 5'1" height translates to 122 pounds - well above what I would expect an elite woman of that height to weigh. At 5'4", a more average height for a woman, it translates to 128 pounds. That also seems too high a weight for an elite racer.
Jacqueline
--------------
19 marathons (3:24:56), 9 30 km ATBs (2:21:33), 2 Midsummer 30 km (2:22:07), 15 half marathons (1:33:53), 5 10 Ks (44:17), 1 5K (22:59), 1 50 K (4:29:22)
2015: London :)
2016: Boston, followed by injury rehab and then ???

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ian
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Re: What limits 5k/10k speed?

Postby ian » Thu Aug 15, 2013 10:19 am

Jogger Barbie wrote:I think that narrow range starts somewhere above 5 feet, and applies to male elite runners only.

Sorry, we weren't explicit about that. I would expect to see a similar linear weight to height relationship for elite female distance runners as well, only with a different proportionality, say, 1.7 instead of 2. The same reasoning applies: over such a narrow range (probably a 15% variation in height among top runners), the non-linear stuff doesn't have enough time to distinguish itself from a linear increase.

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Re: What limits 5k/10k speed?

Postby MichaelMc » Thu Aug 15, 2013 1:03 pm

ian wrote:
Jogger Barbie wrote:I think that narrow range starts somewhere above 5 feet, and applies to male elite runners only.

Sorry, we weren't explicit about that. I would expect to see a similar linear weight to height relationship for elite female distance runners as well, only with a different proportionality, say, 1.7 instead of 2. The same reasoning applies: over such a narrow range (probably a 15% variation in height among top runners), the non-linear stuff doesn't have enough time to distinguish itself from a linear increase.


At the risk of aiding and abetting body image issues, Dr. George Sheehan (running pioneer) had a formula for ideal weight for ELITE DISTANCE RACERS: this is 15% below "normal" athletic weight, so it isn't "healthy" weight by normal standards.

Women: 85lbs for the 1st 5ft of height, 4.25 lbs for every additional inch of height. So 5'4 would come to 102lbs, for example. 5'8 female (Paula Radcliffe) ~119lbs by formula, actual weight... 119lbs.

Men: 93.5 lbs for the 1st 5ft, 4.67 lbs for every additional inch. 5'8 male elite ~131 lbs, 6ft male ~150lbs.

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Re: What limits 5k/10k speed?

Postby Jogger Barbie » Thu Aug 15, 2013 2:23 pm

MichaelMc wrote:At the risk of aiding and abetting body image issues, Dr. George Sheehan (running pioneer) had a formula for ideal weight for ELITE DISTANCE RACERS: this is 15% below "normal" athletic weight, so it isn't "healthy" weight by normal standards.

Women: 85lbs for the 1st 5ft of height, 4.25 lbs for every additional inch of height. So 5'4 would come to 102lbs, for example. 5'8 female (Paula Radcliffe) ~119lbs by formula, actual weight... 119lbs.

Men: 93.5 lbs for the 1st 5ft, 4.67 lbs for every additional inch. 5'8 male elite ~131 lbs, 6ft male ~150lbs.

Thanks, that is interesting! I wonder how much elite runners struggle to keep their weight that much below normal, especially those on the shorter end of the range. You don't need very many calories (relatively speaking) to maintain a weight of 90 pounds...
Jacqueline
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19 marathons (3:24:56), 9 30 km ATBs (2:21:33), 2 Midsummer 30 km (2:22:07), 15 half marathons (1:33:53), 5 10 Ks (44:17), 1 5K (22:59), 1 50 K (4:29:22)
2015: London :)
2016: Boston, followed by injury rehab and then ???

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Re: What limits 5k/10k speed?

Postby fingerboy » Thu Aug 15, 2013 2:34 pm

From reading up on diaries (I dont know if they're real or fake) of females running track in the US they had real issues with this.

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ian
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Re: What limits 5k/10k speed?

Postby ian » Thu Aug 15, 2013 3:35 pm

Jogger Barbie wrote:I wonder how much elite runners struggle to keep their weight that much below normal, especially those on the shorter end of the range. You don't need very many calories (relatively speaking) to maintain a weight of 90 pounds...

Not many calories for basic metabolism, but tons for training. Based on the accounts of the elite runners I've read, the conversations I've had with near-elite runners, and even my own experiences when the mileage has gotten really high, it actually takes some effort to keep one's weight from dropping further, regardless of where it is sitting relative to "normal". The problem arises in the weeks after a big race if the training takes a break but the appetite doesn't: my rail-thin training partner once famously gained over 20 pounds in the month and a half following a fall marathon.

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Re: What limits 5k/10k speed?

Postby MichaelMc » Thu Aug 15, 2013 4:43 pm

ian wrote:
Jogger Barbie wrote:I wonder how much elite runners struggle to keep their weight that much below normal, especially those on the shorter end of the range. You don't need very many calories (relatively speaking) to maintain a weight of 90 pounds...

Not many calories for basic metabolism, but tons for training. Based on the accounts of the elite runners I've read, the conversations I've had with near-elite runners, and even my own experiences when the mileage has gotten really high, it actually takes some effort to keep one's weight from dropping further, regardless of where it is sitting relative to "normal". The problem arises in the weeks after a big race if the training takes a break but the appetite doesn't: my rail-thin training partner once famously gained over 20 pounds in the month and a half following a fall marathon.


Yup,

My weight is VERY stable... until my mileage goes beyond 120km per week. As soon as there is speedwork in that mileage range, then even my notoriously large appetite has a hard time keeping up with the calorie burn. Maybe it is lack of time and energy to eat too.

At that point I go on the wanna diet: I eat anything I wanna. Get used to that for a while and any layoff will throw the scale the other direction.

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Re: What limits 5k/10k speed?

Postby jamix » Thu Aug 15, 2013 6:28 pm

I don't know the exact formula for the relationship between height and weight but if "h" represents height than I imagine the formula would be similiar to that of the volume of a cilinder with respect to its radius.....ie 3.14 x h-3 which is cubic......The average difference between someone who is 5 feet and 5"5 would be 33 percent! Mind you, for simplicity I assumed r = h, for the cilinder. Not sure how much more innaccurate that would make it, but my point is that the relationship between height and weight is likely to be a cubic polynomial.
2013 GOALS:

- Compete in the "Early Bird Sprint Triathlon" in May
- Run a 5km pb during the "Bushtukah Canada Day Road Race"
- Complete an Olympic distance triathlon
- Cycle > 33 km / hr during the cycle portion of a Sprint Triathlon.
- Stay healthy and happy

Races

April 28th: Manotick 10km (40:16)
May 18th: Ottawa Early Bird Sprint Triathlon (DNF)
June 8th: Riverkeeper SuperSprint (2nd overall)
July 1st: Bushtukah Canada Day 5km (18:37)

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ian
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Re: What limits 5k/10k speed?

Postby ian » Thu Aug 15, 2013 7:30 pm

jamix wrote:Not sure how much more innaccurate that would make it, but my point is that the relationship between height and weight is likely to be a cubic polynomial.

Yes, this was Neil's original point. Translated to math-speak, my response is that the tangent-line approximation to the cubic does a pretty good job if you stay within six inches or so of an average height that is roughly ten times larger. Many real-world models, especially those involving imperfectly measured things like human physiology, are a trade-off between accuracy and simplicity. A one-parameter correlation between height and weight (or in the case of the Sheehan formulas, two parameters) is simple enough to be easily explained on a forum like this without creating an inaccuracy which is larger than the inherent variance between individuals. Better?

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Re: What limits 5k/10k speed?

Postby La » Thu Aug 15, 2013 7:43 pm

MichaelMc wrote:
ian wrote:
Jogger Barbie wrote:I wonder how much elite runners struggle to keep their weight that much below normal, especially those on the shorter end of the range. You don't need very many calories (relatively speaking) to maintain a weight of 90 pounds...

Not many calories for basic metabolism, but tons for training. Based on the accounts of the elite runners I've read, the conversations I've had with near-elite runners, and even my own experiences when the mileage has gotten really high, it actually takes some effort to keep one's weight from dropping further, regardless of where it is sitting relative to "normal". The problem arises in the weeks after a big race if the training takes a break but the appetite doesn't: my rail-thin training partner once famously gained over 20 pounds in the month and a half following a fall marathon.


Yup,

My weight is VERY stable... until my mileage goes beyond 120km per week. As soon as there is speedwork in that mileage range, then even my notoriously large appetite has a hard time keeping up with the calorie burn. Maybe it is lack of time and energy to eat too.

At that point I go on the wanna diet: I eat anything I wanna. Get used to that for a while and any layoff will throw the scale the other direction.

I think it also comes down to natural body type. Some people just tend to run thinner, whereas others will always be bulkier. I'm not quite as tall as Paula Radcliffe (1" shorter), but I couldn't imagine being as (relatively) thin as she is without it negatively affecting my health. I'm just not built that way. And why I'm not (and never will be) an elite runner. :lol:

Another point with elite female runners is that very few of them have well developed breasts, and most have fairly narrow hips.
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Re: What limits 5k/10k speed?

Postby MichaelMc » Thu Aug 15, 2013 10:10 pm

La wrote:I think it also comes down to natural body type. Some people just tend to run thinner, whereas others will always be bulkier. I'm not quite as tall as Paula Radcliffe (1" shorter), but I couldn't imagine being as (relatively) thin as she is without it negatively affecting my health. I'm just not built that way. And why I'm not (and never will be) an elite runner. :lol:

Another point with elite female runners is that very few of them have well developed breasts, and most have fairly narrow hips.


Absolutely. We are drastically narrowing the range of body types by limiting it to Elite runners.

Not sure the skinny girls would appreciate their breasts being called poorly developed, mind you. Small, sure, but lets not be judgemental :wink:

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Re: What limits 5k/10k speed?

Postby Jogger Barbie » Fri Aug 16, 2013 8:50 am

MichaelMc wrote:My weight is VERY stable... until my mileage goes beyond 120km per week. As soon as there is speedwork in that mileage range, then even my notoriously large appetite has a hard time keeping up with the calorie burn. Maybe it is lack of time and energy to eat too.

At that point I go on the wanna diet: I eat anything I wanna. Get used to that for a while and any layoff will throw the scale the other direction.

And this is definitely one of those "your mileage may vary/experiment of one" things.

My weight is also very stable, and pretty much what it "should" be for my height (5'1", 106 or 107 pounds). I used to be quite overweight, but lost somewhere between 35 and 40 pounds over 30 thirty years ago and so far they haven't found me again. Because of that earlier history, I am very conscious about how much I eat, and have a running calculator in my head every day that tracks calories in vs calories "earned" via basic metabolism plus exercise. Even at the peak of marathon training, unless I am consciously eating way less than what I would eat with no exercise, I don't lose weight. My preferred racing weight is around 102 or 103 pounds, and part of the reason I had a good race in Ottawa is that I was somewhere close to that. But it was definitely a struggle to get there. My husband Ed, OTOH, while he never gets skinny like an elite runner, always loses weight when he is marathon training, no matter how much he eats.

Leaving aside various individual factors, when you are on the small side, the math just works against you. To maintain a weight of 105 pounds, I need about 1,400 calories per day. Running a km burns about 45 net calories. So a 10 km run gives me an allowance of about 1,850 for that day. Which is a pretty generous allowance, but it's not a huge amount. I will try to work out later what the numbers would be to maintain a weight of 90 pounds, but they'd provide even less "wiggle room".

Of course, for elite runners, they also have the younger metabolism thing working in their favour. At 52, there is no way I'm burning calories at the same rate as a woman in her 20s or 30s!
Jacqueline
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19 marathons (3:24:56), 9 30 km ATBs (2:21:33), 2 Midsummer 30 km (2:22:07), 15 half marathons (1:33:53), 5 10 Ks (44:17), 1 5K (22:59), 1 50 K (4:29:22)
2015: London :)
2016: Boston, followed by injury rehab and then ???

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Re: What limits 5k/10k speed?

Postby purdy65 » Fri Aug 16, 2013 10:35 am

Speaking as another very tiny person, and older, it is becoming CONSIDERABLY more difficult to maintain my weight now, and I will be racing my fall marathon probably 3-5 pounds heavier than my PB marathon 2 years ago unless I start restricting, which I won't do. I hope it doesn't make all that much of a difference. Who knows what a slower marathon would mean though. Training? Age? Weight? So many factors it would be impossible.

I'm constantly told to 'eat a burger' or whatever I want. At one time, I may be been able to sort of get away with that. Not any more. Fact is, the reason I'm even able to come close to maintaining this weight at my size is by doing exactly what JB does - keeping a running calculator. I think I once worked out my basil metabolic rate to be just over 800 calories. Depressing. :(
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Re: What limits 5k/10k speed?

Postby AjaxRunner » Thu Sep 19, 2013 3:03 pm

My favourite quote rgarding ideal race weight comes from Slowman on Slowtwitch:

"the trick is to keep losing weight until your friends and family ask you if you've been sick. then you know you're within 10 pounds. if they start whispering to each other, wondering if you've got cancer or aids, you're within 5. when they actually do an intervention, you're at race weight." - Slowman (Dan Empfield)

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Re: What limits 5k/10k speed?

Postby eljeffe » Fri Oct 11, 2013 12:35 pm

I think the biggest performance limiter for 5k and 10k is how much training time one diverts towards researching, over analyzing, onecdotalizing, and rebutalyzing conflicting research, analysis and anecdotes. Wow, running sure is complicated, the way you guys describe it. :D

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Re: What limits 5k/10k speed?

Postby La » Fri Oct 11, 2013 1:32 pm

Bored, troll?
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