Before you begin training for a half-Ironman (70.3), take note of the swim distance. A 70.3 race typically covers 1.9K of open water swimming, which is only 400m longer than a standard Olympic triathlon.

Next, get a baseline measurement of your fitness and pacing. Triathlon and swim coaches call this your Critical Swim Speed (CSS). CSS is the pace at which you can swim a 1500m time trial. This can be determined by doing a 1500m or 400m/200m time trial. Before doing your test, make sure you get in a good warm up. If you do the 400m/200m test, do the 400m time trial followed by 5-10 minutes of active recovery. Next, do the 200m time trial. Once you have your times, use this CSS Calculator.

Related: How to train for your first half-Ironman

Once you have your CSS, you can begin doing swim workouts that are aimed at increasing your threshold – a key component of a half-Ironman and Olympic swim.

Here are three main set examples of a threshold swim workout:

  1. Longer set length: 3×600 with a 45-second recovery between.
  2. Middle set length: 10×200 with a 20-second recovery between.
  3. Shorter set length: 20×100 with a 15-second recovery between.
The jump from an Olympic distance to a half-Ironman swim is only 400m. Photo: Brad Reiter

Sometimes there just isn’t enough hours in the day. A great way to make the most of the time you do have is adding a quick lunchtime swim. Here are two of our favourite lunch hour swims you can easily fit into an hour:

  • Speed (30 to 35 minutes)
    • Warm-up — 200m: split free and choice
    • Build up — 400m: repeat x 2 – 4 x 50 swim (descending speed)
    • Core — 600m (hard efforts)
      • 100 kick
      • 100 swim
      • 2 x 100 with paddles
      • 1 x 100 pull
      • 2 x 50
    • Cool down — 100m
  • Endurance (35 to 45 min)
    • Warm-up — 100m
    • Build up — 400m
      • 3 x 100 swim, negative split
      • 2 x 50 hard swim
    • Core — 1000m
      • 2 x 200/150/50 swim; progressive
      • 200 pull, even pace
    • Cool down — 100m

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