## An Interview with... Cesar Cielo

Cesar Cielo is a Brazilian swimming world champion. He is the world record holder for 50m freestyle and 100m freestyle. He has been world champion 6 times. He won the gold medal for 50m freestyle and bronze in the 100m freestyle at the 2008 Olympics as well as bronze in the 50m freestyle at the 2012 Olympics when all 8 finalists finished within 0.68 seconds of the winner.

No doubt he is looking forward to the 2016 Olympics being hosted in Brazil.

Cesar is the first interview subject for my "Maths in Sport" series, partly because of my personal history as Senior Men's Champion at Ulladulla Swimming Club (2004-5) and partly because he is such a champion in his sport.

1.  Describe what maths lessons were like for you at school. (Please be honest – not all of us loved maths at school)
I have never had a problem with math. Honestly, I was not in love with it but at the same time it was not a class I hated studying.

2. When you left school, did you expect to be using any of the maths that you were taught ever again?
I knew that a lot of what I have learned was going to be useful. I'm constantly making calculations because of swimming. Its not as complex as it used to be in school but sometimes it gets pretty hard.
For an example, finding the standard deviation for a specific set and compare that to previous times I have done that set.

3. How good do you need to be at mental arithmetic to do calculations in your head as you go up and down the pool?
You don't need to be an expert =) Most of the times I'm counting strokes and calculating intervals on the clock. I think when it comes to the work out in the pool physics also has a great role as we are constantly thinking about the resistance our body creates in the water.

4. How aware are you of angles in your technique – angle of a dive, angle of arms, angle of hands etc?
That's something really important in swimming. From the angle of entry in your dive to the position you want your body be while you are swimming. We are always looking for ways to reduce the drag our body creates and how we can minimize it.

5. When you are racing, how much is “mathematical thinking and calculating” and how much is “swim as fast as you can”?
Racing is more about the feeling and management of your energy and "breath".

6. In a 50m freestyle race, do you count the strokes for the lap and do you know where you should be for each stroke?
Yes, in my 50's I take around 32 to 34 strokes. Depending on how long I go underwater after the start, I could take one more or one less stroke.

7. Do you keep an eye on the clock as you go up and down the pool in training and in races?
Between the efforts yes, while swimming I'm looking to the bottom of the pool and counting my strokes and thinking about my technique and intensity.

8. Have your coaches ever used maths and physics to explain your stroke?
Many times. Physics has a huge role in swimming. The details like starts and turns are easier to see how much physics change the speed you can achieve.

9. Do you look at statistics much to analyse your training and races?
Yes. It's more often in training since you are trying to compare yourself to past seasons and sets that you have done before. In competitions it is more about comparing the races and the technique to see what it could have been done better.

10. Do you have any other insights to offer into how you use mathematics when swimming?
We often use the stop watch to get the "stroke frequency" or the tempo of the stroke to see how fast your stroke cycles are. That's data that only works if you combine this info with some other factors, like technique and stroke length.
For an example, if you take very quick cycles naturally you will have a very high tempo / frequency, but that doesn't mean you are going faster as you have to keep the efficiency through the sprint. We use this data to see if the swimmer is just "spinning" his arms and increasing the tempo and "slipping" water.

Thanks to Cesar for being a contributor to "Maths in Sport". I wish him all the best for 2014 and his future in swimming.

Website - http://www.cesarcielo.com.br/home/