Half Ironman Swim Training: 1.9km Preparation Guide

Training for the 1.9km Half Ironman swim requires building endurance to swim continuously for 30-45 minutes while conserving energy for the 90km bike and half marathon ahead.

The 70.3 swim is longer than Olympic distance but still just the warm-up for the day. Your goal is efficiency and energy conservation, not speed.

Swim Time Targets

Calculate your expected swim time: 70.3 Calculator

Training Philosophy: Efficiency Over Speed

Why Conservation Matters

In 70.3, your swim accounts for only 10-15% of total race time but can affect 100% of your day:

• Exhausted from swim = weak bike
• Weak bike = destroyed run
• Controlled swim = strong finish

The 70.3 Swim Mindset

Weekly Training Structure

Beginner (2 sessions/week)

Intermediate (3 sessions/week)

Advanced (3-4 sessions/week)

Key Workouts

1. Endurance Session

Purpose: Build ability to swim 1.9km+ continuously

Warm-up: 300m easy, mixed strokes
Main: 2,000-2,500m continuous at Zone 2
      Focus on:
      - Consistent stroke count
      - Relaxed breathing (every 3 strokes)
      - Good body position
Cool-down: 200m easy
Total: 2,500-3,000m

2. CSS Threshold Session

Purpose: Build sustainable race pace

Warm-up: 400m easy
Pre-main: 4 x 100m building 1-4
Main: 6 x 250m at CSS pace, 15s rest
      OR 5 x 300m at CSS pace, 15s rest
Cool-down: 200m easy
Total: 2,500-2,700m

Find your CSS pace: CSS Calculator

3. Technique Session

Purpose: Improve efficiency, reduce energy expenditure

Warm-up: 200m easy
Drill Set: 
  4 x 50m catch-up drill
  4 x 50m fingertip drag
  4 x 50m side kick
Main: 8 x 100m as 25 drill / 75 swim
      Focus on one technique element
Cool-down: 200m
Total: 1,800m

4. Race Simulation

Purpose: Practice race-day execution

Warm-up: 300m easy
Race Sim: 1,900m continuous at race effort
         - Sight every 8-10 strokes
         - Practice race start (fast 200m)
         - Negative split second half
Cool-down: 300m easy
Total: 2,500m

Building to 1.9km

Progression Plan

If You Can't Swim 1,000m Yet

Build gradually:

• Week 1-2: 6 x 100m with 20s rest
• Week 3-4: 4 x 200m with 15s rest
• Week 5-6: 3 x 300m with 15s rest
• Week 7-8: 2 x 500m with 10s rest
• Week 9+: 1,000m+ continuous

Technique for Long-Course Swimming

Efficiency Priorities

For 1.9km, technique focus should be:

The Long-Course Stroke

Differences from sprint swimming:

• Longer glide phase
• Minimal kick (2-beat)
• Relaxed recovery
• Sustainable breathing pattern

Key Drills

Learn more: Triathlon Swim Technique Guide

Open Water Preparation

Essential Skills

Sighting Practice

In the pool:

• Close eyes for 5-6 strokes
• Sight forward (wall clock or end)
• Note how straight you swam
• Practice every 8-10 strokes

Open Water Sessions

If you can access open water, include:

• At least 4-6 sessions before race
• Practice in wetsuit
• Practice beach/dock entry and exit
• Build comfort in deep water

Read more: Open Water Swimming Guide

Wetsuit Swimming

Benefits for 70.3

• Buoyancy = less leg kick needed
• Warmth = comfort
• Speed = 5-10% faster typically
• Confidence = psychological boost

Wetsuit Technique Adjustments

Practice in Your Wetsuit

Before race day:

• Pool session (if allowed) or open water
• Practice taking it off quickly
• Note any chafing points
• Apply Body Glide to neck/armpits

Sample 16-Week Swim Progression

Race Day Swim Strategy

Before the Start

• Warm up if allowed (200-400m easy)
• Position based on your speed
• Stay calm, breathe deeply
• Visualize a good swim

The First 500m

• Expect chaos in mass start
• Stay controlled, find space
• Don't sprint even if adrenaline says to
• Focus on finding rhythm

The Middle 1,000m

• Settle into sustainable pace
• Sight every 8-10 strokes
• Draft when possible
• Stay relaxed

The Final 400m

• Maintain pace (don't surge)
• Start thinking about T1
• Loosen wetsuit around neck
• Prepare for beach/ramp exit

Related Resources

• CSS Calculator - Find your threshold pace
• 70.3 Calculator - Estimate race time
• Triathlon Swim Technique Guide - Efficiency tips
• Open Water Swimming Guide - OWS preparation
• 16-Week Half Ironman Plan - Complete program