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Home / Training / Long distance / Sub-1hr session: Perfect your Ironman swim pacing

Sub-1hr session: Perfect your Ironman swim pacing

Going long for the first time? Try this session to get your swim pacing over 3.8km bang on

Swimmer perfecting his swim pacing in training

To swim your first 3.8km well, your pacing needs to be bang on. Joe Beer has the session that will help you time it to perfection…

For this workout you’ll need: a snack around 1hr before (e.g. a sandwich); use your wetsuit if possible; drink before the swim but not during it.

This is a lunch hour/before-work swim or a second session at the weekend if you have several non-training days in the week. It’s great to move up from, say, 3 x to 4 x the main set even if you do sneak into the next hour to achieve it.


10mins as 100s. 10-20secs rest interval (RI) between each 100m.

Main session

3-5 x [300m @ IM goal pace, 30-45sec RI; 200m sighting @ aerobic pace, 30sec RI; 100m @ 1,500m race pace, 60sec RI].


5mins, mix of strokes and sculling.

Performance benefits

Pacing will improve. It’s also possible to change up a gear mid-race if you train with variances of effort. This can be useful when crossing the gap to join a group of other swimmers (nice drafting opportunity) or to deal with swells or currents.

Mental benefits

Swimming around 2km or more when you only have an hour in which to do it boosts confidence, as it requires a no-nonsense approach, limits cool-downs to a minimum and makes the core session hit various skill and metabolic goals.

Physiological benefits

Feeling the rhythm of Ironman pacing over a sustained period ensures that, come race day, you’ll know what that effort should feel like. This session also helps you adjust back to that pace after the fast 100m at the end of each block – good practice for real racing, when a hectic start eventually eases into cruise speed.

The 100m fast-pace element also reminds you of the high effort required, how it affects your muscle endurance when you start to get a bit head-strong, and is a good indicator of how well your swim fitness is improving.

The 200m sighting drill within the main session will prepare you for the open water, when you’ll want to swim the straightest route possible and expend the least amount of energy.

For lots more performance advice head to our Training section

Profile image of Jamie Beach Jamie Beach Former digital editor


Jamie was 220 Triathlon's digital editor between 2013 and 2015.