Statistics Reveals Unfair Height Bias in One Olympic Event

Some sports just aren't fair. Not everyone has  the same chance of exceling at every sport. Some sports you want to be tall, others  short, some lean others massive. That is no surprise. But for one track and field  event the determining factor for who excels is more arbitrary than you would think! Several years ago David Epstein wrote a book called "The Sports Gene"  about improvement in athletics. A big part of that story is how coaches have  determined which specialized bodies are best for th

eir sport, event, or position. In many sports  or events, it is just physics that determines the characteristics of the best bodies. Throwing the shot put calls for tall, massive, and strong athletes to  gain better momentum and energy. Gymnastics calls for shorter bodies  to maximize the power to weight ratio for spinning and twisting. Swimming calls for long torso's and short legs to maximize ease of moving  through the water and minimizing drag, while long distance running calls for short  to

rso's and long legs to maximize running power and minimize dead weight. For example,  even though Michael Phelps, a swimmer, and El Gorrouj, a distance runner, are 7 inches different  in their height, they wear the same length pants. Sadly, there isn't much we can do about  physics. If we want an event to see who can throw a big metal ball far, only a  relatively few number of people are going to have a decent shot of being competitive. However, there is one track and field event were the body t

ype isn't determined by physics. It is determined by an arbitrary choice that a person or commitee made many years ago. A choice  that would forever exculde some people who could have otherwise been champions, even world class,  maybe a face on a wheaties box, but has instead allowed others to dominate instead. What is that event? The High Hurdles. Info Take a look at the line up of the Men's 2020 Olympic  finals for the 100 meters sprint. Now compare them to the 110 Meter Hurdles finalists. One

thing that jumps out is the variation in height for one, and the lack of variation  of height for the other. If you are fast, you can be a good sprinter, but if you are  fast, you still might not be a good hurdler. Why not? Because someone, somewhere  [history] decided that hurdles should be a certain height and a certain distance  a part, and relatively few people have the optimal body characteristics for those distances. Let's consider the distance between hurdles. To be fast, an athlete need

s to be able to  have their natural running stride fit so 3 steps between the hurdles ends within  inches of the optimal take-off spot. If an athlete's natural stride is too long,  they have to shorten their step or studder step, which will slow them down. If an athlete's  stride is too short they have to stretch, which will also slow them down. Notice how even half way through the race, every runner is hitting within inches of  these track marks when they plant. That doesn't happen in the flat

100. So to be an elite hurdler, your stride length has to be just right for  the 4 steps between the hurdles at top speed. Now let's consider the height of the  hurdles. Hurdling the barrier is different than jumping the barrier. Hurdling is  more like stepping over the barrier. Notice that the hurdlers heads don't go up, and  in fact, some go down when they hurdle a barrier. This is because they are trying to lift their legs  over the barrier while minimizing the movement in their center of gra

vity, so that they can snap a  foot back down immediately to get back in contact with the track and accelerate. Time in the air is  not time when you can be adding speed to your run. If a hurdler is too short, they have to  jump more than step, and that means they have to wait for gravity to pull them back  down to get back in contact with the track. Compare this hurdler, whose head goes up over  each hurdle, to these hurdlers, whose heads stay level, or even go down over each hurdle. But if a h

urdler is too short, then they have no choice but to jump to get over the hurdle,  because even going into a tight hurdle bend, they won't get their legs high enough  to go over the hurdles without jumping. So to be an elite hurdler, you have to  be tall enough that you don't need to jump over the hurdles, but not so tall  that your natural stride won't fit the natural rhythm needed between the hurdles. We would hypothesize that the height of elite hurdlers must fall into a narrow range of heigh

ts. To explore this hypoyhesis, we found the heights of 50 world class male hurdlers. This  is the histogram of their hieghts. The histogram suggests that it is difficult to be  an elite hurdler if they are shorter than 6 feet, or 183 cm. Only 4 of the 50 athletes are shorter  than 6 feet, with none of them shorter than 5' 9" [175 cm]. Only 5 were taller than 6'  3", and none taller than 6'5'' or 195 cm. But height isn't neccesarilly the deciding factor.  We really should be analyzing stride len

gth, or leg length. Unfortunately that data isn't  readily available. So we are using height instead since it should correlate highly with leg length. Since male athletes tend to be around the 6 feet to 6ft 3 range (or 183 to 190 cm) then that cuts  out a lot of athletes from being able to compete, and even some entire countries from producing  athletes that could compete in this event. Let's compare hurdlers to sprinters first. The  50 heights of our elite hurdlers have a mean of 73.28 inches [

186 cm], and a standard  deviation of 1.77 inches [4.5cm]. Whereas the heights of 50 elite 100 meter sprinters  in the world have a mean of 71.46 [181.5cm] and a standard deviation of 2.68 [6.8cm]. Assuming that the heights of these elite athletes are normally distributed, here  are what those distributions look like compared to the US male height distribution. The US male height distribution has a mean of 69 inches [175cm] and standard deviation of 3 inches  [7.62cm]. (We are using the united s

tates in this weeks video, whose height distribution is similar  to many other European countries, but we will look at other countries in our video next week) We can use an integral to estimate the proportion of US males that fall within 2  standard deviations of the mean for height of elite hurdlers. We take 2 SD's as the upper and  lower bound for height of being an elite hurdler. Here is something to notice. The shortest height  of an elite hurdler is the average height of a US male. The aver

age height of an elite hurdler,  73.3 inches or 186cm, is almost 1.5 standard deviations above the average US male height. Something we could conclude from these graphs is that someone who is fast and tall (maybe  in the sweet spot between 6'0" and 6'4", where about 90% of our sample falls) might have  a better chance of excelling in the hurdles, simply because there is less competition there. About 90% of the heights of elite hurdlers fell between 6 feet and 6' 4". Using this normal distributio

n calculator, we find that only about 15% of US males are in  this optimal range for hurdling, but competing in the flat 100 meter sprint pulls about 90% of  elite athletes from 5'8" to 6'3" [172-190cm], at least according to our sample, and  about 62% of US males fall in this range. Is there a similar story in the women's hurdles?  Lets compare the same three distributions. This is the distribution of heights of 50 world class  female hurdlers, and this is the distribution of heights of 50 worl

d class female sprinters  in the 100m, and this is the distribution of heights of US adult females. There is a  different story here than with the males. There is not as much separation between  the three distributions. Hurdlers are still taller than sprinters, and sprinters  are taller, on average than the population as a whole. But there is a lot more overlap. 90% of our elite hurdlers were in the range of 63 to 70 inches [160-178cm]. About  57%, of US females fall into this range. Much larger

then the 15% for men. So why aren't elite female hurdlers so much taller than the average female height, like  with the men? There could be two culprits, the distance between the hurdles or,  the height of the hurdles themselves. It is hard to know how to analyze the  effect the length between hurdles has on the height or stride length of the hurdlers.  If you have ideas, put them in the comments. One first step is to look at the ratio  relationship between the distance between hurdles and the

average elite hurlder height.  The average height of an elite male hurdler is 73.3 inches, and for the men's 110m hurdle  the distance between hurdles is 30ft [9.14m]. That is a ratio of 4.91, or it takes  4.91 average hurdlers laying down end to end to stretch from hurdle to hurdle. One the women's side, the ratio of average elite hurdler height and distance between hurdles is  5.03. Surprisingly close, so nothing dramatic here that might point to why there is a larger spread  in the distributi

on for heights of women than men. Let's look at the height of the hurdles next. With  men's high hurdles standing at 42" or 106.7 cm, that puts the hurdle height at more than  60% the height of the average US male. For women, the high hurdles are 33  inches or 83.8cm. So the hurdles are about 52% of the height of the average  female, quite a bit lower than the men. This means females can be  shorter and still hurdle, rather than jump, the barriers during the race You can see by comparing the men

's and women's olympic finals from tokyo that the women,  especially the tall ones, do not need to bend their bodies much to go over the hurdles, but the  men are extremely bentover when they hurdle almost hitting their knee with their chin. So what could we do to make the hurdles a sport that more people,  especially males, could excel at? We will share our idea, but if you have ideas on  how to open up the hurdles to more competittors, put them in the comments. Or if you know of  other sports

where an arbitrary rule changes who can be competitive in the sport? put that in the  comments as well. Here are some of our own ideas. We could lower the hurdle height  for men, so shorter people could compete. That might make it more like the  women's race, where it is not so exclusive. We could also have three high hurdle races. One  at 110 meters with the current hurdle height, one at 105, hurdles, with shorter hurdles, and  one at 100 meters, with even shorter hurdles. Then almost anyone co

uld have a  race that would fit their height. Another strategy is to change the rules. Why do we  have to have the hurdles all at the same positions on the track? Other events allow some flexibility. Long jumpers and high jumpers don't have to start all at the same spot. Pole vaulters can start at different positions and adjust the  position of the bar relative to the pit. Why can't hurdlers adjust the hurdles  like polevaulters, within some minimum and maximum distance. This would allow  some p

eople to be competitive in an event that is arbitrarily stacked against them. Now, do we really think that the governing board for international athletic competitions  will take these seriously. No, of course not. They might actually counter with the fact  that there are other sports and events, some of which give smaller bodies a better  advantage, like diving and gymnastics. No one is being forced to just do the hurdles. But what we have learned is that it can be to your advantage to pick a sp

ort that  plays to your body type. But if you are not a perfect fit for a sport you enjoy, don't  fret about it, and keep doing what you enjoy. We can learn a lot from the women in the 100m  hurdles. The last olympic gold medalist was Jasmine Camocho-Quinn at 5'8' or 173 cm. But there  were only two hurlders in our list of 50 that came in at the shortest, 5'1" or 155cm both two inches  shorter than the next hurdlers in our sample. One of them took third, earning the olympic bronze  medal, (Megan

Tapper from Jamaica), and the other still made the olympic final, and later broke  the world record (Tobi Amusan from Nigeria).