Athlete Profiling – Swim

Athlete Profiling – Swim

Athlete profiling. Sounds weird. It kind of is. It’s essentially the compiling of an athletes numbers and data to make them go faster.

There is safety in numbers as the saying goes. This is very much the case in performance sport. It’s a different interpretation however. The safety the numbers provide in this context are the training zones and intensities. The numbers allow for intensity distribution and load management enabling the program to maximize gains in performance and minimize risk of injury or burnout. Athlete profiling is therefore the data recipe for success!

There are an infinite number of test sets and time trials that a coach can give their athletes but the best tests are those that provide the greatest, most relevant data for the least training disruption. 

*It must be noted however that the numbers from athlete profiling typically come from test which are often in controlled “lab” conditions. Therefore not necessarily true indicators of performance. This is especially the case for triathletes who will be tested in each discipline in isolation but do not complete the disciplines in isolation come race day. Therefore use athlete profiling to create a data-driven program but don’t let the numbers dictate the performance level of athletes. It’s the race results not the lab data that count ultimately*


The standard swim test that provides a good data is the test for CSS or critical swim speed. It’s an approximation of your lactate threshold speed and you can find it by doing a couple of swimming tests. It’s not precisely the same as lactate threshold but it will be extremely close and plenty accurate enough to guide your training.

The test involves two timetrial swims – a 400m and a 200m.  Before attempting these swims perform a thorough warmup and a small build set to get you used to swimming fast.

Do the 400m timetrial first, it’s less likely to affect the 200m than the other way around. Recover completely between each timetrial with some easy swimming. Perform both timetrials from a push off from the wall, not a dive.

Try and pace the trials as evenly as possible, don’t start too fast and slow down. If you’re not sure get someone to take your 100m splits – they can be very revealing.

CSS (m/sec) = 200 / (T400 – T200) is the formula to work out CSS pace per 100m. This provides 3 crucial pieces of data in the two time trial results themselves and the subsequent CSS value generated. This will give zones that allow the coach and athlete to work through the correct distribution of intensity in the training program. This calculator comes curtsey of coach Phil Mosely on

There are more tests that can be performed of course and will add greater depth to the athlete profile, but this is the ideal start point. Reams and reams of stats and figures isn’t going to make an athlete become Richard Varga overnight (or ever in truth) but it will indeed enable the program to be geared towards maximising progression.

A coach can go deeper and record additional variables such as splits, stroke rate, heart rate, lactate etc and then combine this with video footage and analysis. If that coach has the ability to communicate well with their athlete and the athlete is receptive to the input then that’s when sh1t gets real! That’s when the magic of athlete profiling happens!!! 

Many thanks for reading this blog post. Please get in touch if you have any questions or suggestions or want to know more on this topic as a short blog post only scratch the surface.

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