Training for an Ironman Swim

Swimming, March 23, 2021

In this article, we discuss some of the basics of swim training for a beginner Ironman. We look at how you can structure your sessions, how many a week and for how long to help you on your way to your first Ironman 226

Training for Ironman can be a daunting prospect, so we’ve put together a how-to guide to get you on the right track to make your first Ironman triathlon as fun and straightforward as possible.

What is an Ironman?

An Ironman triathlon (also known as full distance, 226 triathlon or 140.6 if your old school like us) consists of a 3.8km swim, 180km cycle and 42.2km run. These are completed one after the other, with athletes finishing between 7:51 (Current world record) hours and 17 (cut off time for most races) hours. The training for this type of event will take some dedication and consists of multiple months of training, with most athletes training six days a week on average with multiple sessions on some days. As you can imagine with the distances and times involved, a good portion of this training will include lots of time swimming, cycling and running, and one of the key sessions for any aspiring Ironman athlete is their long swim, bike and run, which can be up to 6 hours at a time for cycling, which can be a logistical nightmare for a self-coached beginner athlete.

Taking on an Ironman triathlon isn’t always an easy decision and having a well thought out, and structured training plan will make things much easier to fit in around your normal already hectic schedule. Plus, following a training plan has been shown to improve your success rate up to 2x that of an athlete who doesn’t.

Training for the Swim

Historically most athletes we see regard themselves as poor or average swimmers, and this is usually the one area where athletes, in general, are most worried about. Ultimately the swim only makes up approximately 5% of the overall distance on the day, but it is the one area with some focus and persistence that can make or break your race day.  For most athletes improving your technique whilst building your ability to cover the distance is all that’s needed to end up having a great day.

We would advise splitting your sessions between the following (assuming three sessions a week):

  1. Technique swim – a short to medium length swim with lots of rests, and short distances swam with a clear focus on technique improvement through drills and conscious and deliberate practice. (start small 25metre efforts and then build until the technique drops off and rest and repeat). These sessions should be approx. 20-45 mins long
  2. Long swim – This swim is purely focussed on developing your aerobic ability in the water and ultimately your ability to cover 3800 metres non-stop. Again, these sessions should start with smaller repeats and overall distance and should build up to covering the race distance at least a few times without stopping over the training programme’s length. Start at 100m repeats and build the distance until you can cover 38 of them with minimal rest, then add try 150’s, 200’s 300’s and so on until you can swim 3800m without stopping. These sessions should build-up to last between 1 hour (for faster swimmers) – 1:30 and beyond. Don’t focus too much on time, more on the distance and progression.
  3. Interval swims – These sessions are focussed on swimming faster than your race pace, they have several benefits not least improving your fitness, along with this they can help you become more comfortable at swimming at higher speeds along with helping you find out where ‘too fast’ begins when swimming longer distances. These sessions can be mixed with technique or endurance sessions to give you some variety and help you develop either of these further. I would suggest starting with 4-6x25m repeats with long rests (20-30 seconds) between each repetition and swim at an 8-9 out of 10 effort for each repeat. You won’t need many of these to see a benefit, so sticking within a 4-10 repeats range and going no longer than 75 metres with your interval distances will give you a good balance of effort and speed. Build up slowly and fill the rest of the session with either endurance or technique. Aim for these sessions to last approx. 30-40 mins.


One significant addition to these is open water swimming, and all Ironman Swims will take place in open water. You will need to have the confidence to swim in it too. Take a look at what type of swim you have for your event and try to get in a similar environment at 4-6 times before your race. Even getting in open water once or twice before will give you the confidence to complete on race day.  For more information, the sessions we offer on this and help/guidance, email us at