As a take home message:
- Racing strategy can depend from the energy expenditure per split
- It was estimate the energy expenditure per split and over the full race for the men’s 200m free medalists at the 17th Asian Games (gold: Hagino Kosuke, JAP ; silver: Sun Yang, CHI; bronze: Park Tae-Hwan, KOR)
- Hagino spent between 5.01 (100-150m) and 6.17 (0-50m) kcal per split. Sun’s expenditure per split ranged between 6.8 (100-150m) and 8.1 (0-50m) kcal
- Higher speed and body surface means a higher drag and therefore more energy needed to overcome the external force.
In Asia swimming is a very popular sport and swimmers are true national heroes. For instance, the Korean Park Tae-Hwan has an aquatic center named after him. The Singaporean Joseph Schooling is headlines in local mainstream media on regular basis. Sun Yang is a major star in China and pushed to be a role model to Chinese youth. So in this region everybody was looking forward for the 17th Asian Games (held in Incheon, Korea) and notably the swimming competition. Probably the best performances were delivered in the men’s 200 free final by the “freshman” Hagino Kosuke (Japan, 1:45.23, 2nd best time in 2014) and Sun Yang (China, 1:45.28, 4th best time in 2014). Surprisingly, the last spot in the podium was reserved to Park Tae-Hwan (Korea, 1:45.85). Later on the Korean shared that he was filling such a pressure to deliver good performances in his home country, in a venue named after him, that he was sorry to fail in such way and disappoint the fans.
Another major sport event held in Asia last month was the Singapore F1 Grand Prix (GP). The Marina Bay street circuit, in downtown Singapore is the most spectacular F1 GP. Well… that is the opinion at least of the 5.5 million people living here (including me); even though the arrangements for this street circuit are disruptive of our daily life for a week. For those who follow my posts is no surprise telling you that I like motor racing. A few times I did analogies between F1 or MotoGP with competitive swimming. Obviously, I attended the race held on my doorstep. During the race, I monitor cars’ fuel expenditure per lap.This gave me an idea: “I could estimate the swimming energy expenditure per split during an official event!” Literature reports a few procedures to measure the energy expenditure during testing and training sessions (Savage and Pyne, 2000; Barbosa et al, 2014), time trials or simulated races (Figueiredo et al., 2012). The challenge though is to have such insight during an official event. Swimmers cannot be instrumented with sensors or equipment as F1 cars. Even if they could, most wouldn’t fancy the idea because the drag force would increase, the technique changed and the performance impaired (Barbosa et al., 2010). Nevertheless, just like in F1 or MotoGP, racing strategy might depend also from the “fuel expenditure per lap”.
I came up with a mathematical model to estimate the energy expenditure per split of the men’s 200m free medalists at the 17th Asian Games. This kind of analytical approach is selected on regular basis in F1 and other motor racing sports. I won’t bother you with the math. However my model includes the swimmer’s anthropometrics, speed, drag, propelling and mechanical efficiencies. In an earlier post I addressed the topic “energy expenditure and nutrition”. That mathematical model is straightforward and does not include so many individual traits i.e., it is not so customized to each swimmer, which is fine if we want to monitor the balance between energy intake and energy expenditure. Today my aim is different, hence we need a more comprehensive and accurate model.
The split times were retrieved from the official website (figure 1). It’s impressive how Hagino was able to shift to a higher gear and speed-up in the last split (the 150-200m split was 26.00s). In the remaining splits he was the slowest of the three swimmers, which can help to explain this. Anyway, after the last turn he was almost 1s second behind the leading swimmer and was able to win the race (turn at 150m: Hagino 1:19.23; Sun Yang 1:18.30).
Now let’s go to the main focus of this piece. Energy expenditure (also known as metabolic power) is reported in Watts (which is the International System of Unit for power, figure 2 – panel on the top) and in kilocalories per split (figure 2 – panel on the bottom). I was wondering if most of us would have a good understanding of how much power or energy is expended per split if reported in Watts or Joules. We all are familiar with the unit “kcal”. I guess this is a nice way to understand the amount of energy we are talking about.
The trend is almost the same for both graphs (figure 2). Sun Yang is the swimmer that expended more energy and Hagino the most economic, at least in this race the most economic was also the more effective (i.e. delivering the best performance). Sometimes this does not happen at all. I do not want to drift away from today’s topic, but for instance at the Rome 2009 WC, Paul Biedermann broke the WR (1:42.00) albeit Michael Phelps (1:43.22) was more efficient than the German. I will share this data some other time. Moving on…
Hagino spent between 5.01 (100-150m) and 6.17 (0-50m) kcal per split. Sun’s expenditure per split ranged between 6.8 (100-150m) and 8.1 (0-50m) kcal. The highest energy expenditure happened in the fasted split, while the lowest in the slowest one. Besides that, the Japanese is only 1.75m tall, with approximately 68kg of weight and the Chinese 1.98m, 89kg. Over the full race Hagino, Sun, Park spent 21.89, 28.82 and 24.21 kcal, respectively. Higher speed and body surface means a higher drag and therefore more energy needed to overcome the external force.
- Barbosa TM, Silva AJ, Reis AM, Costa M, Garrido N, Policarpo F, Reis VM (2010). Kinematical changes in swimming front Crawl and Breaststroke with the AquaTrainer® snorkel. Eur J Appl Physiol 109: 1155-1162
- Barbosa TM, de Jesus K, Abraldes JA, Ribeiro J, Figueiredo P, Vilas-Boas JP, Fernandes RJ (2014). Effects of Protocol Step Length on Biomechanical Measures in Swimming. Int J Sports Physiol Performance. On-line first.
- Figueiredo P, Barbosa TM, Vilas-Boas JP, Fernandes RJ (2012). Energy cost and body centre of mass’ 3D intracycle velocity variation in swimming. Eur J Appl Physiol. 112: 3319-3326
- Savage B, Pyne D (2000). Swimmers. In: Tanner RK, Gore CJ (eds). Physiological tests for elite athletes. pp. 435-448. Australian Institute of Sports. Human Kinetics, Champaign, Illinois.
By Tiago M. Barbosa PhD degree recipient in Sport Sciences and faculty at the Nanyang Technological University, Singapore