12 Week 70.3 Ironman Training Plan - Advanced
"> Stop Guessing. Start Training With Purpose.
Designed by accredited Triathlon and Endurance running coach Grant Hornsby, this 12-week structured Half Ironman program removes the uncertainty from training and provides a proven pathway to race-day success.
Every swim, bike and run session has been carefully designed to develop the physiological attributes required to perform at your best over the 70.3 distance.
Whether you're chasing a personal best, aiming for the podium, or simply striving to become the fastest version of yourself, this program provides the structure, progression and accountability needed to get there.
What's Included
- ✅ 12 weeks of structured training
- ✅ Detailed swim, bike and run workouts
- ✅ Compatible with TrainingPeaks and most GPS devices
- ✅ Progressive session design with clear race-specific objectives
- ✅ Strategic recovery and overload cycles
- ✅ Proven endurance coaching methodology
Weekly Structure
- 3 Swim Sessions
- 4 Bike Sessions
- 3 Run Sessions
Every workout includes specific pacing and intensity guidance, so you know exactly how hard to train and why.
Why This Program Works
Unlike generic online plans that simply prescribe distance and duration, this program is built around five core principles:
- Consistency
- Intelligent Pacing
- Progressive Overload
- Structured Recovery
- Purposeful Repetition
Each session is included for a particular physiological reason and contributes to a specific performance outcome.
Designed By
Grant Hornsby
Level 2 Advanced Running Coach
Triathlon Australia Accredited Coach
Bachelor of Applied Science (Human Movement)
Post Graduate Diploma (Exercise Science)
With more than 30 years specialising in endurance coaching and experience preparing athletes across swimming, cycling, running and triathlon, Grant's programs combine sports science, coaching experience and real-world racing knowledge.
Ideal For Athletes Who
- Are preparing for a Half Ironman (70.3)
- Want a professionally designed program without the cost of ongoing coaching
- Prefer structured, easy-to-follow training
- Want every workout planned in advance
- Are committed to reaching their potential on race day
Your Job Is Simple…
Open the session.
Complete the workout.
Trust the process.
I've already done the thinking for you.
O2 Endurance Coaching is brought to you by Grant Hornsby - an accomplished age group Marathon and Cross Country runner and 3x Ironman World Championship representative.
Grant is an accredited Lvl 2 Advanced Athletics Australia running coach, Triathlon Australia certified coach and holds a B.App.Sci. (Human Movement) and Post Grad.Dip. (Exercise Science).