## An interview with... Etienne Daille

Etienne Daille is a French kayaker who competes in the K1 slalom. He was overall individual World Champion in 2012 as well as being part of the French team that came first in the 2012 European Championships and third in the 2013 World Championships.

Etienne kindly agreed to answer some questions about how maths relates to his sport of kayak slalom. Here is what he had to say.

Describe what maths lessons were like for you at school.
I studied math until university. It wasn’t the matter that interested me the most because, it was sometimes too abstract.

When you left school, did you expect to be using any of the maths that you were taught ever again?
Some things yes, because I study in a ‘’Sport University’’

How good do you need to be at mental arithmetic to do calculations in your head as you race?
During the race, you need memories, skills, openness, adaptability, quick thinking... But, sometimes during the race, you can listen to the speaker say intermediate times. You can calculate your differences with the best. See if you lose or gain time at every ¨split time¨. To know if you need to take more risks to win the race...Just after the race (the finish line), the mental arithmetic can help you to calculate different rankings.

How aware are you of angles in your technique – angle of approach into a corner, angles in the course, angle of arms, angle of body etc?
The approach angle of the gates is very important, including upstream gates. There is a lot of perspective effect, it’s difficult to take good benchmarks. It’s important also to have a good proprioception of your body so you don’t touch the slalom gates.

When you are racing, how much is “mathematical thinking and calculating” and how much is “go as fast as you can”?
I'm focused on the trajectory and speed of the boat. If it goes well, then the time will be good.

Is estimation good enough or do you rely on accurate measurement of distances and times?
For the time, I need a stopwatch. And for distances, often a camera to compare the trajectories on the computer.

Do you keep an eye on the clock as you go around a course in training and in races?
There are many things to manage: I rather focus on what I have to do on the water when I paddling. I have a look on the clock when I finish the course.

Have your coaches ever used mathematics and physics to explain your style and movement?
Slalom is a sport that uses ‘’open skill’’. There are very different morphologies of kayakers. The courses are different for each competition. So there are many different styles of kayakers. You must understand your style and the track to choose the best movement to go as fast as possible. This requires to use also mathematics and physics not only for the race but also to choose the best equipment for you.

Do you look at statistics much to analyse your training and races?
Yes, to analyze the regularity of performance, penalties, the choice of trajectories...

Do you have any other insights to offer into how you use mathematics in racing?
Yes, when you developing and testing a new shape of kayak. For example, you need to compare the new shape with any other kayak. To do it, you make lot of different tests. And to analyse these tests, you use for sure mathematics, statistics...

Thanks Etienne for being a part of the Maths in Sport project. Good luck for the 2014 season!