Ironman Base Builder – Athlete Overview

This 12-week plan is designed for athletes aiming to build a solid aerobic foundation for an Ironman or long-distance triathlon. It’s best suited for athletes who already have a basic endurance base (able to complete workouts in the 60–90 min range) and want to systematically increase fitness while minimising injury risk.

Plan Structure:

Weekly Layout: 3 bike, 3 run, 2 swim sessions, starting each week with a recovery day

Intensity Guidance: Bike and run sessions are based on Threshold HR, swims on RPE

Weekly Volume: 7–10 hours, progressively increasing across the block

Equipment Needed:

Aside from essential swim, bike, run kit, you will need a way to track your heart rate during workouts. A heart rate strap is best, but a GPS watch with heart rate tracking will do.

Communication:

This plan is structured for self-guided use, but weekly adjustments can be made based on fatigue, HR responses, or schedule changes.

If you’re working with a coach, share session completion and HR/RPE feedback to inform future adjustments.

Who This Plan Is For:

Athletes seeking a controlled, progressive build of endurance and threshold fitness before moving into race-specific build and peak phases

Those who want a structured, repeatable framework for all three disciplines

Individuals aiming to avoid overtraining while establishing a strong aerobic base