Analyzing the Olympic 100-meter sprints
As always, the whole world was focused on athletics this summer at the Tokyo Olympics took place. Within the athletics program, the men’s and women’s 100 meters were the in the spotlight. Behind the historic performances is a treasure trove of data that helps look in more detail at the event, learn about it, and identify the latest trends in sprinting. Below are some insights on overall performance levels, how well maximum velocity and acceleration correlate, top speed, speed loss, race modeling, and more.
Making the Olympic final is harder than ever
The long-awaited Tokyo Olympics displayed one of the highest standards ever in sprinting, in both men and women contests. While no official world records were set, Su Bingtian ran the fastest times ever recorded between 10 and 60m in men’s semi final, and Elaine Thompson’s result of 10.61 is the fastest 100m ever into the wind (-0.6).
The standard of competition also reached new levels. While sub10 and sub11 were necessary to reach the podium during the early 2000s, this is now required to just make the final over the last decade and Tokyo confirmed this trend. To get on the podium is even more difficult as shown by Shericka Jackson’s 10.76 for bronze, the best ever mark for 3rd place in a 100m race.
The relationship between max velocity and acceleration
LaMonte Jacobs broke his PB (9.96) in each round, 9.94, 9.84 and 9.80, to get the Olympic title in Tokyo. The final 2 times were also new European Records. Improving twice an Area Record in major champs didn’t happen since high altitude Games in Mexico 1968 with Jamaican Lennox Miller for Central America & Caribbean. But one result from the semifinal is perhaps even more impressive for track nerds. In an extraordinary race by Su Bingtian, he beat the pace of Usain Bolt’s world record up to 60m (6.29 vs 6.31).
Su (1.72m tall) was already known as a phenomenal starter. Prior to Tokyo he already shared the fastest 30m ever recorded in 3.76 with Christian Coleman and Maurice Greene. His 3.73 now makes him a clear leader on the all-time list which contains half a dozen of men in 3.77 or 3.78. His 50m in 5.45 and 60m in 6.29 are well beyond the official world indoor records (5.56 and 6.34).
His start technique has been analyzed in details in the IAAF Biomechanical report for 2018 World Indoor Championships where he took silver in 6.42, which remains his PB. In Tokyo it was essentially the same, with trademark being very low positions out of the blocks, acute projection angles and short air times.
Su Bingtian’s first 30m represents the current upper limit in human’s sprint acceleration ability, and thus can serve as a reference for further research. Using JB Morin’s spreadsheet for Force-Velocity-Power profiling, here are the calculated parameters for the first 30m for Su Bingtian, compared to other Tokyo medallists and other historical data (from 5m split analysis) for men and women sprinters:
As expected, there is a tendency to find the highest calculated F0 and Pmax display in the best starter and accelerators (Su, Fraser-Pryce), while the higher sprint velocities tend to be associated with lesser Drf (Bolt, Griffith-Joyner) … and vice versa. Indeed, it seems to be a trade-off relationship in maximum theoretical F0 and V0 production.
Training considerations for max velocity vs. acceleration
For elite sprinters (unlike beginners or non-specialists), improving both concurrently is unlikely, as each call for different and probably conflicting abilities, regarding time (contact/air time ratio) and direction of force application (horizontal/vertical ratio). Which should be prioritized at training? Should sprinters focus on their best feature or their shortcomings? While training towards a more balanced force-velocity ratio (addressing shortcoming) seems to be the most effective strategy to improve the start-acceleration phase, it may affect negatively the maximum sprint velocity phase. In fact, the top speed (reached about 6 sec after the start of the race) has the highest relationship with 100m final result. Caution should prevail in choosing training options to elicit further improvements in elite sprinters. In this respect it’s worth mentioning that the 5 best 100m women sprinters of all-time (Griffith-Joyner, Thompson-Herah, Fraser-Pryce, Carmelita Jeter and Marion Jones) reached their career fastest top speed, but not fastest first 30m during their 100m PB.
Interestingly, the shorter the running distance, the less difference is found between men and women. This observation recently made by McClelland & Weyand can be verified with acceleration data and split times during 100m race. The difference in the fastest 0-30m ever recorded is 7.7%, Su and Fraser-Pryce), smaller than the 9.4% found in the top speed & speed maintenance section (30-100m, Bolt and Griffith-Joyner). The relative (to body mass) force and power display in the best female starter is very close to what is found in some elite male sprinters. Training implications of these observations are still unclear and opened to debate.
Comparing Tokyo to the world records
In this section I present some intermediate times at 30m, 60m and 80m comparing the world record to the performances in Tokyo. Times at 30, 60m, 80m and 100m are enough to describe the velocity evolution along the race, according to the analysis framework by Hess (GDR, 1973). First 30m represents the acceleration, 30m-60m maximum velocity section 1, used also at training with the fly 30m test, 60m is the indoor competition distance, 60-80m section represents max velocity section 2, and the 80-100m speed maintenance/endurance ability. For Tokyo analysis, 3 high speed cameras (up to 210 frames per second) in the stands were used, TV multiple view replays were used to check athletes’ positions. 30m and 60m times were measured using visible makers on the track, 80m split was calculated using splits at 76.84m and 81m markers.
Su Bingtian left the impression to have run his final during the semi-final, although both races seem to have been run with full effort. The importance of distribution of effort, even for events as short as the 100m sprint, is illustrated in these two races. In semis, after a monster start and power display, his last 40m was 3.54. In final, after a slower reaction time and lower acceleration production, he was able to cover the last 40m in 3.50. This trade-off situation has been explained by Tom Tellez.
Like Su in semi-final, Elaine Thompson-Herah was one pace for the world record until 60m mark. This means that what separates her from Griffith-Joyner performance lies in the speed-endurance area. A couple of weeks after the Games in Eugene, this time was +1.5 wind, she again reached 60m in 6.87 but finished stronger as she was timed in 10.54. Will further improvements next year come from better speed endurance, or better acceleration, or a bit of both?
The importance of top speed
Top speed remained the king in Tokyo. It was once again the sprinter who produced the highest maximum velocity was the winner : Jacobs was the only one to reach 12m/s. This observation bares one exception in the history of major champs time analysis: 2017 World champs final when Simbine reached 12.0m/s yet only placed 5th.
The top speed data presented in the table above are from the 3DAT technology data shared on television. It’s beyond the scope to evaluate their accuracy, however, the difficulty to measure top speed has been a technological challenge for over a century. One of the difficulties with tracking devices is that the speed curve shows acceleration and decelerations during each step and smoothing the curve is necessary to get valuable information. For example, Donovan Bailey’s 9.84 in 1996 Olympic final was the first world record to be analyzed using a laser gun, and location of top speed varied from 50 to 59.8m depending on the chosen smoothing factor of the instantaneous running velocity curve. Laser gun used in major champs (1996 Olympics, 1997, 2007, 2009 and 2011 world champs) have constantly found top speed to occur in average around 6.1-6.4 sec after the start of the race for the best sprinter as well as for lower performers (of course, since the best sprinters run faster, they cover more ground per distance, so reach top speed farther into the race, but not later).
However, the top speed recorded by 3DAT in Tokyo 2021, at this year’s US Olympic Trials, and also at the 2017 World Championships during a pilot study, also show a 7.2-7.4 range in average, i.e. 1 sec more that was usually found with laser gun. The theory saying that the new generation spike shoes help reaching top speed later can’t be proven by this limited data, especially since the pilot study done in 2017 also found top speed after over 7 seconds for the world champs finalists, when these shoes didn’t even existed yet.
A recent study proposed to look at a Top Speed Interval (TSI), which is the time or distance covered while sprinting at or very near top speed. This would have the advantage to bypass the almost impossible task in practice to locate top speed and a plateau rather than a peak describes better what is actually recorded in smoothed velocity curves in sprinting.
Analyzing speed loss
What happens after top speed is reached? Here is is interesting to analyze the step parameters to see how they are affected by speed loss after top speed is reached. The following table shows step length (SL) and step frequency (SF) during the TSI and 2.5 sec after top speed was recorded by Omega to assess speed endurance (SE):
In all sprinters, confirming countless previous studies, step frequency is reduced for a variety of reasons: due to longer contact times, as a result of neuromuscular fatigue, and because less applied force traded for longer force application on the ground during impulse.
The change in step length is individual, it is usually either maintained or slightly increased, but this increment is never enough to compensate step frequency loss (having in mind that sprint velocity is the product of step length x step frequency) as in the case of Thompson-Herah and Kambundji. Fraser-Pryce experienced dramatic speed loss in Tokyo final for her 10.73 race, and it is interesting to note that she set her 10.60 PB in maintaining SL while marginally decreasing SF. Knowledge of how parameters fluctuates for each athlete as they run faster or slower is precious in order to prescribe individualized workouts and cues.
The future of sprinting and race modeling
The 2021 season and Tokyo Olympics made several impacts on all-time 100m lists. Several continental records were broken this year (Men’s Africa, Asia, Europe, women’s Africa, CAC) and 8 men and 5 women improved their marks among the all-time top 20. Despite all the improvements, an analysis of times doesn’t show any new trend. Indeed, the splits taken for the updated world lists look surpisingly alike when compared to the model table published after 1988 Olympic Games by Prague University:
The 1988 Model was designed using split times in 399 races ranging between 9.79 and 11.60 for men and 334 races 10.54-12.80 for women recorded between 1978 and 1988. For the purpose of this report, I chose to show the 1988 model for 9.80 and 10.70 which are now required to hope to get a medal. While by 1988 only 1 man (doping DQ) and 1 woman had run faster than these time, it is quite surprising to see how accurate the Prague table still is, compared to the model I calculated using split time analysis for almost all of the current all-time best performers.
This shows how sprinting structure hasn’t dramatically changed in over three decades, in spite of notable performance improvements in sprinting, as for now 10 men (+2 doping DQ) have run faster than 9.80 and 5 women under 10.70. Only 0.02 difference is found at 60m in both men and women, the consequence is that in those two categories, 100% top speed is now found in the 60-80m section (called Top Speed 2 by East German authors) and no longer in the 30-60m section (called Top Speed 1). This means that for a given performances, contemporary sprinters tend to reach top speed later than what sprinters were able to in the eighties.
How much has the evolution in technologies, especially track surface and shoes, contributed to this tiny change? And how much further improvements of these material as well as training content will impact the 100m sprint performances in the next 30 years? We’ll have to wait and see.
