open water swimming mistakes
Credit: James Mitchell
Training > Swim

Open-water swimming technique for triathletes: 11 common mistakes

Tri swimming coach Annie Oberlin-Harris explains 11 common mistakes triathletes make in the open water swim and advice on how to correct them

3 Not researching the swim race course

Here’s a map of the Blenheim Triathlon Sprint Course (swim course in purple):

The majority of the course is a straight line, following a row of small buoys on your left hand side. There’s a sharp left turn at a larger buoy about 650m, with another 100m to go to the swim exit. So you’ll have one left turn to make over the whole course. Many courses use a rectangular shape, however, this was the course at Zurich Ironman 2015:

So three sides of a square, under a bridge, exit over an island, diagonally cut the square and complete a triangle before exiting after the bridge. An interesting course but it helps to have studied it first! I find it useful to head down to the race the day before and take mental images of the entry and exit points as well as doing a thorough recci of the start and finish, if you’re competitive you’ll want to know where you’re going to line up if it’s a mass start (unlike Zurich and many other Ironmans which let 10 people go every 10 seconds, much safer if you ask me).

4 Having a CO2 freak out

We touched on this in my last article that covered 9 swimming technique mistakes triathletes make. Holding your breath, even momentarily can lead to a build up of carbon dioxide in the blood, leading you to that ‘panic bell’ moment where you’ve reached your lactate threshold and your body says no more. If you’re untrained for endurance swimming or you go out too hard this will happen even faster. We’ve all seen the athlete starting at the front and breastroking after 75m. This is very common and completely avoidable if you practice good exhalation technique.

How do I stop feeling out of breath when swimming front crawl?

 Trickle breathing versus explosive breathing in front crawl


To exhale properly, after taking a breath in through your mouth, immediately let your face relax, jaw drop and just let the air go without pausing. Any tension in your facial muscles will restrict the airflow, leading to more carbon dioxide storage. (Don’t pretend you’re blowing out candles!) The aim is to breathe out as much as you can and as relaxed as you can. This helps to replenish a large volume of air every time you breathe and access the lower part of your lungs where the majority of the oxygen and carbon dioxide exchange happens. Whether you favour breathing every two or three strokes, breathe out right from the start of the race and this performance hump will be a part of history.

Continue reading our guide to 11 common open-water swim  mistakes (3/4, faults 5-7)


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