Sunday was the men's 100m final at the Paris Olympics, and the difference between first and second place was 0.005 seconds, decided by a shoulder dip to the line. Immediately after the race, I received about 50 messages asking if aerodynamics might have played a role in the race outcome. Having worked adjacent to several running projects over the years, I thought the answer was probably yes.

The women's 100m final was won by a wide margin, so even though some athletes could have chosen better equipment, there was little talk about the difference aerodynamics made.

It is intuitive to the average cycling, skiing, speed skating, or swimming fan that aerodynamics (or hydrodynamics) is a very important factor in performance; they watch footage of races in the early 2000s and wonder, "If they weren't wearing those loose-fitting jerseys, How fast would they have been if they weren't wearing those loose-fitting jerseys?" is anyone's question. So why do runners continue to wear loose-fitting vests and not tie their hair up?

The answer is because they don't think it makes that much difference. In this article, I will explore what the differences actually are and what can be done under the current rules to achieve faster times (spoiler: there are many).

First, let's quantify the impact of aerodynamics on running times. In cycling, it is often said that 80% of the resistance a rider faces at 40 km/h is due to aerodynamic drag, but we know that in running this is much less; Schickhofer and Hanson* found that in 2021, at 36 km/h, 8.5% of an athlete's energy is They found that 8.5% of the athlete's energy is used to overcome drag. Some extrapolation of this result shows that at 43 km/h (the top speed seen in the men's 100 m) this increases to 10%.

The reason this contribution is much smaller than cycling at essentially the same speed is due to the physics of the running motion. The athlete must raise the center of gravity with each stride, which accounts for most of the energy in running. However, if athletes could reduce their resistance, they could still find much more performance.

A study** conducted in the 1980s showed the effect of aerodynamics on race times. The researchers calculated that in the 100m race, a 2% reduction in aerodynamic drag would reduce the finish time by 0.01 seconds. Since the men's 100m race in Paris was settled in half that time, how can it be said that a 1% change in aerodynamic drag would have changed the outcome?

The same study also found that a 2% reduction in aerodynamic drag improved marathon times by 5.7 seconds, with other events in between.

Comparisons with some other results and my previous marathon studies show that this is still an accurate figure.

Now here's the fun part.

5.1. "In all competitions, athletes must wear clothing that is clean and designed not to cause discomfort. Clothing must be of a material that will not become transparent when wet. Athletes shall not wear clothing that obstructs the view of the judges."

This is the only rule in athletics that governs the materials of clothing that may be used and where they may be placed (apart from name/number bibs on the front/back of the athlete). Combined with the results we saw earlier, it is clear that the athletes have a lot of time left.

Just before the Paris Olympics began, Bart Brocken published a study*** that examined the differences in resistance due to hairstyle and clothing choices in women's long jump. He found a 36.6% reduction in drag from worst to best hairstyles, from loose shorts to tight vests, from loose curly hair to swim caps/ bald heads. Applying this to the calculation of time reduction, this could result in a reduction of 0.183 seconds in the 100m race.

However, most athletes wore tight-fitting shorts and reasonably tight running vests. A closer look reveals an 18.2% difference between loose-fitting shorts and tight-fitting shorts, reducing the potential aerodynamic drag and time savings based on the survey results to 18.4% and 0.092 seconds. In addition, the study was conducted using a female mannequin and did not capture the effects of leg movement. It is also unclear if the same drag reduction effect applies to male athletes, but since this is the best and most recent data we have, we will have to go with it for now.

An interesting result from Brocken's study is that there was a 4.4% drag reduction between using a tight fitting vest and a loose fitting vest, which, based on studies from the 80s, translates to a time reduction of 0.022 seconds for the 100m. The men's final was won by 0.005 seconds, with the second place runner using a loose-fitting vest. Even if the time reduction from the stationary female mannequin to the male runner does not fully reflect the difference, it is doubtful that it made a difference. Aerodynamics are highly individualized, so without testing Kishanne Thompson, it is impossible to say whether the relaxed vests were the deciding factor in the race results.

What is not included in the study is to look at different fabric textures and placement. To me, there is great potential here. Against bare legs, the best calf guards in cycling/triathlon can reduce aerodynamic drag by up to 10%. And using a full skin suit with long sleeves and shorts stretched as far as possible can reduce it by another 10%. In other sports, we have seen that greater savings are possible through the use of skinsuits and fabric choices. Of course, running is in a different position than cycling, but this is a conservative estimate based on tests I have seen firsthand.

There have been no studies (that I have been able to find) on shoe aerodynamics. This is despite the fact that the foot is moving at almost twice the athlete's average travel speed (Clark et al. ***); for a 100 m run, the peak speed of the foot is over 80 km/h. Understanding the drag and lift characteristics of the shoe could lead to significant savings, since drag increases proportionally to the square of the velocity and the foot travels very fast in the running stride. I have not tested this, so I can't show it numerically, but a good model would give us an idea of what is possible here (master's thesis idea, anyone?).

I think it is not unreasonable to think that by using tight fitting clothing and developing new clothing and footwear solutions with fabrics suitable for the aerodynamic demands of racing, we can reduce aerodynamic drag by 30%. In a 100m run, a time reduction of 0.15 seconds is possible That's right. This would not only make a difference in the outcome of the race, but could also put the sprint world record back within reach. The same method could be applied to all running with similar results: the Ineos 1:59 Challenge showed that aerodynamics can make a difference even at low speeds (even small ones).

This may seem unrealistically large to some, but to those who do, I say look where cycling has come from. From loose-fitting jerseys and no helmets to the present, aerodynamic drag and rider performance have decreased significantly. In athletics, aerodynamically speaking, there are still easy wins.

I don't want this article to seem like I am saying that cycling is a better sport than running. For years, cycling has been the worst sinner in ignoring sports science, especially when compared to swimming, skiing, and speed skating, which are decades behind.

It is important to remember that despite Kathy Freeman's and Nike's introduction of the Swift Suit in Sydney, track and field has yet to really embrace aerodynamics in a serious way. It is not without good reason, and the gap is much smaller than in all of the aforementioned sports. However, now that times are slower than in swimming, cycling, speed skating, etc., it is time to get started.

* Schickhofer and Hanson , 2021 Aerodynamic effects and performance improvements of running in drafting formations

** C.R. Kyle, V.J. Caiozzo, 1986 The effect of athletic clothing aerodynamics upon running speed

***Bert Blocken et al. 2024 Numerical-physical modeling of the long jump flight of female athletes: the effect of jumping style, hairstyle, and clothing

****Clark et al. 2023 Horizontal foot speed during submaximal and maximal running