So it really IS true -- running is harder for some of us!

Finally...some validation of what has been discussed and debated on here before! I always had a gut feeling that taller people were better runners (or just ran with greater ease), and there may be something to it after all:

From http://www.drmirkin.com

Dr. Gabe Mirkin's Fitness and Health e-Zine
October 28, 2007

Longer Lower Legs More Efficient

People who have longer lower leg lengths (the distance
from knee to ankle) will usually have greater endurance during
running or walking than those with shorter lower leg lengths.
Researchers at the University of Wisconsin showed that people
with longer lower legs use less energy when they run (Journal
of Human Evolution, August 2007).
In a previous paper in the same journal, these authors
showed that people with longer lower legs are better able to
prevent heat build-up, which slows you down and makes you
tired. When you exercise, almost 80 percent of the energy that
you use to power your muscles is lost as heat. So the harder you
exercise, the more heat you produce and the harder your heart
has to work to get rid of the extra heat. You prevent heat buildup
by your heart pumping hot blood from your muscles to the skin
where it is cooled by sweat and conduction and radiation.
People with longer lower limbs use up less oxygen and
produce less carbon dioxide for the same energy expenditure.
Therefore they are more efficient and can go further because
their bodies require less oxygen.

--
Emily, very short in the lower leg and always have a tough time running

Isn't this referring to the proportion of lower leg to upper leg length? Not that someone is necessarily taller. Just my take on it.

Taller athletes are actually less efficient as runners -- they have more body weight to carry and more body mass to move through space.

Taller athletes are built to be swimmers.

Quote:

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Originally Posted by velogirl

Taller athletes are built to be swimmers.

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Hmm...maybe THAT was my issue on the swim team!! :D

I don't know about that...my DH is 6'6" tall and the swim does not come easy to him....but he runs like the wind.

Now before you say it..yes he can swim. He is a very good swimmer and trained with me in the pool all summer. But those long legs just sink......

Huh, interesting. Isn't it the opposite for cycling (relatively long femurs are advantageous)?

Quote:

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Originally Posted by velogirl

Isn't this referring to the proportion of lower leg to upper leg length? Not that someone is necessarily taller. Just my take on it.

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Hmmm, I can't tell. The word "proportion" is not used, so I took it to mean the actual lower leg length -- the area of that part of the body, as it were. And since taller folks tend to have taller lower legs.... but I haven't read the original study, just the blurb in the Mirkin newsletter.

If your interpretation is correct, I'm still running-challenged as I have long femurs for my (short) height! ;)

Emily

I think the article is valid, if all other things are equal. The arguments alone don't really hold. If it was a simple matter of having more skin to dissipate heat, then it would reason that large people would be more efficient runners. But as someone already pointed out, larger = more mass = more work.

I'm above average height for a female (5'7"), but I have relatively short lower legs. (And I have a hard time with running). Like Emily, I seem to have long femurs for my height. DH is 6'5", is an average runner, below average swimmer, and above average cyclist. He has pretty long lower legs, but he weighs 204 which is just a lot of mass to move.

It would be interesting if the study looked more at the proportion of lower leg to upper leg (and to overall height). . . .

Here's the abstract of the actual study, the highlight is mine:

Quote:

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The evolution of human running: Effects of changes in lower-limb length on locomotor economy

Karen L. Steudel-Numbers, a, , Timothy D. Weaver1, a, and Cara M. Wall-Schefflera
aDepartment of Zoology, University of Wisconsin, Madison, WI 53706, USA
Received 19 September 2006; accepted 9 April 2007. Available online 14 June 2007.



Abstract
Previous studies have differed in expectations about whether long limbs should increase or decrease the energetic cost of locomotion. It has recently been shown that relatively longer lower limbs (relative to body mass) reduce the energetic cost of human walking. Here we report on whether a relationship exists between limb length and cost of human running. Subjects whose measured lower-limb lengths were relatively long or short for their mass (as judged by deviations from predicted values based on a regression of lower-limb length on body mass) were selected. Eighteen human subjects rested in a seated position and ran on a treadmill at 2.68 m s−1 while their expired gases were collected and analyzed; stride length was determined from videotapes. We found significant negative relationships between relative lower-limb length and two measures of cost. The partial correlation between net cost of transport and lower-limb length controlling for body mass was r = −0.69 (p = 0.002). The partial correlation between the gross cost of locomotion at 2.68 m s−1 and lower-limb length controlling for body mass was r = −0.61 (p = 0.009). Thus, subjects with relatively longer lower limbs tend to have lower locomotor costs than those with relatively shorter lower limbs, similar to the results found for human walking. Contrary to general expectation, a linear relationship between stride length and lower-limb length was not found.

Keywords: Limb length; Energetics; Human running

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Thanks blueskies for posting the abstract!

So it is a proportion thing then, I misinterpreted. It would be interesting to see the tables for a given body mass showing what is considered a relatively "long" lower leg vs. an average or short one. I suppose most folks would end up with an "average" lower leg for our height. I do know that I always have to push my saddles back far on the rails to get my knee over the pedal spindle, on bikes with different seat tube angles even, so I am assuming I have a relatively long femur for my height....and although I kinda enjoy running, I'm not good at it and it's always hard, no matter how much I train.

Emily

It's a statistically significant finding, but that doesn't mean it's one of meaningful magnitude. If you're not trained in statistics, that basically means there's a difference that's correlated to relative limb length, but doesn't say anything about the magnitude of difference. Also, a correlation in the .6 to .7 range that they've found, only accounts for 4-5% of the variance that they found, if I remember my statistics.

Basically, it could be a very small difference (can't tell from what's reported), and the limb length (relative to body mass) only accounts for 4-5% of that variance.

From what I understand the article is referencing the entire lower limb which in medicine = the whole leg, relative to body mass. So the article does not seem to differentiate between femur length or lower leg length, just the lowere limb as a whole.

It is true that biomechanical differences exist. It was (I use the past tense because I have not been in contact with this type of research for a long time) believed that people of African descent had a biomechanical advantage in running due to limb length and pelvis angles. That is one of the reasons, back in the day, that it was thought that a caucasion would never out run an African. Simple genetic biomechanics. I don't know if this research or theory has withstood the test of time. I've been out of the feild for about 14 years.

Silly question - but it seems like someone with longer legs and therefore a longer stride would automatically have an advantage over someone with short legs and a short stride - like I have to take 2 steps for each one my husband takes so of course he can out run me.......

btw - for cycling its supposedly the opposite, a long femur gives a biomechanical advantage (though a long foot is supposed to counterbalance any advantage a long thigh gives?? - its all about levers on a bike)

Eden, it's all about levers running too. You have to think about how a long pendulum swings versus a short pendulum. If I hung a weight from a rod that was 2 feet long and created a pendulum wiht the rod swinging at let's say 2 swings per second (Hz), as I moved the weight up the rod the pendulum would swing faster under the same energy output. I'm not entirely sure that I'm remembering my University physics well but I believe it's a linear relationship, so if I bring the weight up to 1 foot the pen, if thedulum would swing at 4 Hz. The big difference in running is that your foot isn't planted during the swing phase of gait so you can have control over how long your lever is, by bending the knee more, you shorten the lever and can increase your turn over. This is why sprinteers practically hit their butts with their heels. If they didn't, they wouldn't be able to bring the non-weight bearing leg through fast enough to create adequate turnover for speed.

There's a lot of controversy about this right now in the running world. Is it better to train an endurance athlete to run with a form more ismilar to a sprinter's so that theoretically they can go faster or should they minimize energy expenditure by using a gait where the feet do not lift far from the ground? They may not go as fast over short distances but they might last better over the long haul. urrently, in triathlon, your best runners are short, have quick turnover and a good strength to weight ratio. The fastest pros are predominently below average height for the general population.

All right, I'm blathering. But I really do like to talk about this stuff.