The Best IRONMAN 70.3 Workouts

When it comes to IRONMAN 70.3 triathlon training, not all workouts are created equal.

In this feature we reveal four of the most effective workouts. Master these four essential sessions, for your best race ever. Be warned that they may take you several months to build up to.

1. IRONMAN 70.3 Bike Reps

  • Why? This trains your body to cope with the intensity of a IRONMAN 70.3. You should start off with a few efforts and build up over time.
  • How? Ride at around 76 to 82% of your maximum heart rate. If you have a power meter, aim for 75 to 85% of your FTP. This requires real focus but is sustainable for several 30-minute efforts in training. You should just about be able to talk.
  • When? Once or twice per week. Build up to 3 or 4 efforts of 30-minutes each.
  • Tip: To do this session properly you’ll need an open stretch of road without many traffic lights or junctions. Alternatively, do this session on an indoor bike.
  • Example Session: 3 x (20 mins at 76-82% of Max HR (75-85% of FTP) with 5 min recoveries). Include a 15 minute warm up and warm down.

2. The IRONMAN 70.3 Long Ride

  • Why? This trains your body to cope with a 90km ride. You need to get to a point where this distance feels manageable in training.
  • How? Aim to ride at around 65 to 70% of maximum heart rate. This requires some focus but should feel fairly comfortable. You should be able to hold a conversation throughout.
  • When? Once per week is enough, typically at the weekend. Start off with shorter distances and build up to 90km (this might take you several months). Ideally, you want to ride the full 90km two or three times in training before you race.
  • Tip: Practice using the nutrition you’ll use on race day. For example, use the exact gels or bars you have planned for your big race.
  • Example Session: Ride 3 hrs at 65 to 70% of maximum heart rate.

3. Threshold Run

  • Why? Popularised by esteemed running coach Jack Daniels, these threshold running reps help to raise your lactate threshold in order to help you run longer at a faster speed.
  • How? You’ll need to Determine your Run Threshold Pace.
  • When? Once per week. You could also incorporate your long run into this session, by gradually increasing the warm up and warm down.
  • Tip: Don’t run too fast. The idea of this workout is to stick to your threshold pace (as defined in the point above). If you go too fast, you will lose the specific training benefit.
  • Example Session: Warm up: Run easy for 15-minutes. Main Set: 4 x (6 mins at threshold pace with 60-second jog recoveries). Warm down: Run easy for 10-minutes.

4. Threshold Swim Set

  • Why? Your CSS (Critical Swim Speed) equates to your current best time for a 1500m swim. Training at this intensity helps you prepare you for the rigours of an IRONMAN 70.3 swim.
  • How? You’ll need to Determine your Swim CSS. To work this out, time yourself for a 400 and 200 swim (go as fast as you can) and then go to our CSS Calculator to find your Training Zones
  • When? Twice per week. You could also include a 400-600m warm up and a 200m warm down, including technique drills.
  • Tip: Don’t go too fast for the first few efforts, otherwise you won’t be able to hold the same pace for the last few.
  • Example Session:
    8 x 50m at 1500 race pace + 5 secs rests
    4 x 100m at 1500 race pace + 10 secs rest
    3 x 200m at 1500 race pace + 20 secs rest
    1 x 300m at 1500 race pace


Our IRONMAN 70.3 Training Plans feature these workouts, as part of a structured, periodised training program.

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Phil Mosley (Coach & Founder)
Phil Mosley (Coach & Founder)

Phil is a recognised expert in the field, having featured on many endurance sports publications. He founded MyProCoach in 2010 to sell premium training plans complete with email coach support for triathlons, duathlons, running & cycling.

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About Phil Mosley

About Phil Mosley

Phil is a successful coach & athlete, having sold over 20,000 training plans on TrainingPeaks and been featured on countless publications. His focus is on smart training that still leaves quality time for your family, friends & career. You can learn more about MyProCoach™ here or preview your training plan now.

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