Half Ironman (70.3) Training Guide: 16–20 Week Plan, Race-Week Prep, and Insider Tips

Signing up for a Half Ironman (70.3) is a huge accomplishment—congratulations!
Whether you want to finish strong, set a personal record, or use this race as a stepping stone to a full Ironman, success comes from structured training, smart fueling, and race-day preparation.
This guide draws on official IRONMAN and Strava resources to help you plan and execute a confident race.

Build a 16–20 Week Plan That Fits Your Life

You can choose between two proven approaches:

16-Week Plan — Ideal if you already have a solid swim-bike-run base.
IRONMAN suggests three sessions per discipline weekly, one long bike, one long run, and a quality swim session.
20-Week Plan — Perfect for gradual build and more base endurance.
Strava outlines an eight-week base, six-week build, and a six-week race-specific phase to safely increase volume.

Tip: If you only have four months, prioritize consistency and recovery. If you have five months, use the extra time to add longer base rides, runs, and more race-specific bricks.

Key Workouts: Bricks, Threshold, and Long Endurance

Your week should mix volume and intensity:

Long endurance sessions: Extended aerobic rides and runs to build stamina.
Threshold/FTP intervals: Boost power and race-pace control on the bike.
Brick workouts: Bike-to-run or swim-to-bike sessions that train the body to adapt between disciplines.

Sample Brick Workout

90–120 min bike with 3×10 min at race pace
Follow immediately with a 10–20 min easy run and 3×3 min at planned half-ironman run pace

Repeat bricks every 7–10 days in your final build phase and practice transitions and nutrition during these sessions.

Fueling: Practice, Schedule, and Electrolytes

You can’t improvise nutrition on race day—practice your fueling plan in training.

Bike nutrition: Eat and drink every 15–20 minutes. Use semi-solids early, switch to gels or chews later to ease digestion.
Pre-race: Take a gel 30 minutes before the swim and sip electrolytes beforehand.
Hydration: Test your sweat and sodium losses; adjust electrolytes to avoid cramps and GI issues.
Consistency: Replicate aid-station products in training so you know how your stomach responds.

Race Week: Pacing and Logistics

Taper: Reduce volume but keep short race-pace efforts to stay sharp.
Bike pacing: Keep power around 85% of FTP or under ~85% of max heart rate.
Run pacing: Aim to stay below 90% of fresh 10K pace as fatigue builds.
Arrive early: Check in, review transition flow, and rehearse your morning routine to minimize stress.

Set a clear race goal—finishing strong, chasing a PR, or preparing for a full Ironman—then align pacing and nutrition with that goal.

Gear Checklist and Mental Prep

Essential items for your first 70.3:

Wetsuit, goggles, tri suit
Bike and helmet
Running shoes and race belt
Body lube and hydration supplies

Optional upgrades as you progress: power meter, aero helmet, race wheels.

Mental preparation: Visualize transitions, plan mantras for tough moments, and rehearse solving issues like flats or cramps during training.

Final Thoughts

A Half Ironman rewards consistency and smart race execution.
Commit to a 16–20 week plan, practice your fueling, and stay flexible with conditions on race day.
Crossing that finish line will be the payoff for months of disciplined training and thoughtful preparation.

How to Prepare for a Half Ironman: Swim, Bike, Run Guide