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Race Kinematics of Olympic Swimming Gold Medalist Anthony Ervin

It seems like it was only yesterday, but the Olympic Games were held six months ago. There are several amazing stories and achievements to be recalled. Arguably one of the biggest headlines of the Olympic Games was in the 50-m free Olympic Swimming race when Anthony Ervin from USA grabbed a shocking Gold Medal. At the age of 35, 16 years after Sydney 2000 and having endured several challenges in his life, he wins again a gold medal in the men´s 50m freestyle [curious if entry times improved at the Olympics?].

He is the oldest individual Olympic gold medalist in swimming. Putting into perspective, Ervin´s come back and achievement are far more impressive than this. It is the story of how one is able to overcome the hurdles that come across in his life and, by the way, eventually wins another gold medal. But on this blog we cover the swimming “science”. The aim is to stick to our mission and this time I am sharing with you the race analysis (split times & kinematics) and an estimation of what might have been his energetics. If you are looking for more his back story, we recommend his book: Chasing Water: Elergy of an Olympian.

 If you are looking for more back story and don’t want to buy his book, checkout these two pieces.

Split Times and Reaction Time on Olympic Swimming Gold Medalist Anthony Ervin

Race analysis was carried out as usual by video analysis on in-house built software. The typical error of the measurements is 0.01s. The variables selected are the one reported on regular basis here by me.

His reaction time was 0.69s (table 1). Not being impressively quick, it was better than what he performed in the semis (0.72s) and similar to the final at the US Trials (0.67s). Not too good, not too bad. It seems he played it safe to avoid a false start.

Anthony Ervin 50-m Free Olympic Swimming Breakout 2016 Rio Olympic Games
Anthony Ervin 50-m Free Olympic Swimming Breakout 2016 Rio Olympic Games

Underwater he performed 5 underwater kicks followed-up by 4 arm-strokes between the water breakout and the 15m mark. As most Olympic swimming freestyle sprinters, he stayed underwater for less time than what we are used to see in other events. However, Anthony Ervin surfaced much earlier than other Olympic swimming sprinters.

Between the 15m and the 45m marks the speed slows down. This is expected to happen assuming that over an all-out bout there is the decay in the production of energy by immediate sources.

To cope with this fact, over the 15-45m stretch he changed his stroke kinematics. The stroke length is getting shorter and to tackle this impairment, he must increase the stroke rate.

If the stroke length decreases this means that there is an impairment of the mechanical power output per stroke cycle. This is a way of having some insight on the overall swim efficiency.

Another way is referring to the stroke index that confirms this fact. (The stroke index (SI), considered one of the swimming stroke efficiency indexes). The stroke index is indeed decreasing over the 15m–45m stretch.

Upon visual inspection of the underwater images we can note that he keeps a high head position, looking slightly forward. He features a very “smooth” technique. He doesn´t seem to be “struggling” to displace in the water. It is smooth, it seems an easy swim, but yet very powerful. For instance, the splash in the hands´ entry is not as obvious as for other finalists. There is turbulence surrounding him, but yet not as much as for others.

The hands´ path underwater is something between the typical S-stroke pull and the straight pull (i.e. only a slight bending by the elbows during the insweep).

Side note: Watch the race video above. At  11.4-12.3s in the race, refer to the swimmer in lane 4 (Olympic swimming World Record (in short course meters) holder F. Manaudou, France, silver medalist. Don’t forget to checkout the great power analysis we did on Florent Manaudou). If I am not wrong or mislead by the camera´s perspective, his right arm performs a very obvious S-stroke pull, whereas the left arm is completely extended. I am wondering if this could lead to a slight asymmetry in the propulsion by both arms. The right arm is producing thrust mostly by enhancing the lift force, whereas the left arm the propulsive drag.

flourent manaudou biomechanics arm path
Flourent Manaudou biomechanics arm path

In the last 5m Anthony Ervin did 4 arm-strokes, increased the SL and hence the speed. This enabled him to have a rather good and clean touch on the wall, at least as far as we can understand by the video.

Energetics of Olympic Swimming Gold Medalist Anthony Ervin

Trying to have a deeper insight I have used a set of analytical procedures to estimate his energetics. I have selected the model by Capelli et al. (1998) and the assumptions reported by Figueiredo et al. (2011).

The total power (Ptot) is the sum of the power by the anaerobic alactic system (AnAl), anaerobic lactic system (Anl) and aerobic system (Aer).

Cappelli et al. (1998) reported that the partial contribution of the Aer in a 50m event is about 15% of the total power. Hence, the main contribution comes from the two anaerobic sources.

I have no clue of how much was his peak blood lactate at the end of a 50m Olympic swimming race. The finalists at the Canadian Swim Championships were noted as having 9.1±1.9 mmol/l of post-race blood lactate in the 50m events (some great research by Greg Wells, checkout his Swimming Science Interview). In a 50m distance, there isn´t enough time to produce too much lactate. However, I decided to be conservative and estimate his energetics for a very wide range of lactate concentrations.

His anaerobic alactic power was estimated as being 3.884 kW (table 2). This parameter does not depend on the blood lactate though. For instance, if his post-race peak blood lactate was 10 mmol/l, the anaerobic lactic power was roughly 1.899 kW and the aerobic power 0.997 kW.

This represents a contribution to the total anaerobic pathway of 67.17% and 32.83% by the alactic and lactic systems, respectively.

We can note that the partial contribution by the lactic system increases with a higher post-race peak blood lactate.

For those less familiar on this topic, producing lactate is not a bad thing though. More lactate being produced means that more energy is delivered by the anaerobic lactic system (a.k.a. “glycolysis”).

The draw back here is the clearance of the blood lactate. In a nutshell, swimmers must be able to produce a lot of lactate and yet clear it as fast and efficiently as possible. They don´t want to change too much the cell´s pH, they need to send the lactate back to the liver as quick as possible and convert it into pyruvate. If this is properly done, the pyruvate is converted into glucose or glycogen and ready to be used in the next race (the phenomenon is known as “gluconeogenesis”). In fairness, this is even more important in the 100m and 200m events, but we should not disregard this issue in a short sprint.

Race Energetics of Olympic Swimming Gold Medalist Anthony Ervin

Take home message:

  • The aim was to run the analysis of Anthony Ervin´s race winning the gold in the final of the Olympic Swimming men´s 50m freestyle at Rio 2016.
  • It was measured the split times, race kinematics and estimated the energetics.
Olympic swimmer Anthony Ervin
Olympic swimmer Anthony Ervin


  • Capelli, C., Pendergast, D. R., & Termin, B. (1998). Energetics of swimming at maximal speeds in humans. European journal of applied physiology and occupational physiology, 78(5), 385-393.
  • Figueiredo, P., Zamparo, P., Sousa, A., Vilas-Boas, J. P., & Fernandes, R. J. (2011). An energy balance of the 200 m front crawl race. European journal of applied physiology, 111(5), 767-777.
  • Vescovi, J. D., Falenchuk, O., & Wells, G. D. (2011). Blood lactate concentration and clearance in elite swimmers during competition. International journal of sports physiology and performance, 6(1), 106-117.

By Tiago M. Barbosa PhD degree recipient in Sport Sciences and faculty at the Nanyang Technological University, Singapore

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