Beginner’s Guide to Ironman 70.3
Summary
Thinking about stepping up to a Half Ironman? This beginner’s guide to Ironman 70.3 covers everything you need to know, from race distances and weekly training structure to key workouts, fuelling tips and race day strategy. Whether you’re building from sprint and Olympic races or diving straight into long-course, this post will help you train smarter, avoid common mistakes and get to the start line confident and prepared.
What Is an Ironman 70.3?
The Ironman 70.3 also known as the Half Ironman, is the sweet spot of triathlon. It’s far enough to be a serious challenge, but achievable enough for anyone with drive, discipline and a solid plan. Whether you’re coming from a sprint background or diving straight into the endurance world, this guide will help you build smart, stay motivated and cross that finish line strong.
Unlike full Ironman races, the 70.3 format is accessible for athletes with busy lives. But don’t let the “half” fool you. It’s still a full-on endurance challenge. The Ironman 70.3, often called the “Half Ironman,” covers, you guessed it, 70.3 miles (113 kilometers) of racing.
That includes:
1.2-mile (1.9 km) swim
56-mile (90 km) bike ride
13.1-mile (21.1 km) run
How Long Does It Take to Train for an Ironman 70.3?
Training Time Required: Most beginners typically train for a period of 16 to 24 weeks, dedicating about 8 to 12 hours each week. This training volume gradually increases, reaching approximately 12 to 15 hours during the peak weeks of preparation. If you’re starting from scratch with little to no prior experience, it’s advisable to allow yourself at least six months to build endurance and skills safely. However, if you are already active in one or more sports, such as swimming, cycling or running, you might be able to prepare and be race-ready in a shorter timeframe of around 4 to 5 months.
Ironman 70.3 Training: Discipline by Discipline
Swim (1.9 km)
The goal in the swim isn’t just about speed; it’s primarily focused on maintaining comfort and maximising efficiency in the water.
Focus on:
Staying relaxed. A calm, steady pace will set up your whole race.
Sighting practice. Learn to look ahead every few strokes to stay on course.
Open water sessions. If your race is in a lake or ocean, train outside the pool when you can.
Key Session: 4x400m swim with 30 sec rest; focus on smooth, steady pacing
Train 2–3 times per week with a mix of technique work, continuous swims and intervals.
Bike (90 km)
You’ll spend the majority of your time here on race day, so it’s important to prioritise building strong bike fitness.
Ride 3 times per week: one long ride, one interval/VO2 max session and one easy recovery or brick ride.
Learn to fuel on the bike, this is your mobile aid station.
Key Session: 2-hour ride with 3x10 min at race effort, 5 min recovery.
Run (21.1 km)
Frequency beats distance. Run 3–4 times per week, including long runs, threshold sessions and easy bricks off the bike.
Build endurance before speed.
Practice pacing on tired legs.
Key Session: 10 km run with 3x7 min at threshold pace, 3 min easy.
The Four Pillars of 70.3 Training
1. Progressive Overload
Gradually increase volume and intensity over time to effectively stimulate adaptation while minimizing the risk of injury. Follow the 10% rule carefully, ensuring that you do not increase your training load by more than 10% each week to allow your body to adjust safely and sustainably.
2. Recovery Weeks
Every 3–4 weeks, make sure to schedule a recovery week during which you reduce your training volume to about 60–70%. This intentional decrease helps your body to adequately adapt, repair and rebuild stronger for the upcoming training phases.
3. Brick Sessions
Practice the transition from bike to run (T2) regularly. Brick sessions are essential as they train your body to smoothly handle the challenging shift from cycling legs to running legs, helping improve overall performance and reduce fatigue during the race.
Example Brick: 30-minute bike + 5-minute run warm-up + 20-minute tempo run.
4. Race Nutrition Practice
Fuelling is a critical fourth discipline in triathlon. It is essential to train with your planned race nutrition strategy, paying close attention to nutrition intake, especially during long workouts. This practice helps ensure your body adapts and performs optimally on race day.
Common Mistakes First-Time 70.3 Athletes Make
Skipping strength training: Include functional strength 1–2x per week.
Neglecting open water practice: Pool skills don’t always transfer.
Overtraining: More isn’t better. Smart recovery leads to real gains.
Ignoring race-specific gear: Test your race kit, shoes and hydration setup in training.
Inconsistent pacing: Go too hard on the bike and your run suffers. Know your zones.
Race Day Strategy for First-Timers
Swim: Start calm and steady. Find your rhythm early and focus on relaxed breathing. Don’t get caught up in the chaos, swim your own pace and stay in control.
Bike: Stick to your pacing zones and nutrition strategy. This isn’t a bike race, it’s the first half of a triathlon.
Run: Expect to feel sluggish at first. Start slow, build pace later. Walk aid stations if needed, many pros do it, too.
Mental Tip: Divide the race into chunks. “Just get to the next buoy. Just get to the next aid station.”
Mini FAQ: Starting Your First Ironman 70.3
What are the distances in an Ironman 70.3?
It includes a 1.9K swim, 90K bike ride, and 21.1K run (half marathon), completed in succession.
How long should I train for my first 70.3?
Most beginners need 4–6 months of structured training, starting with a solid base and gradually building volume and intensity.
How many hours per week should I train?
Plan for 7–10 hours per week on average, with long sessions on weekends and a rest or recovery day built in.
Do I need to do a full 70.3 in training?
No. You’ll gradually build close to race distance in each sport, but full-distance simulations are not necessary and can be counterproductive.
What gear do I need to get started?
The essentials: a reliable bike, a pool or open water access, proper running shoes and a basic watch or training app to track your progress.
FURTHER READING: BUILD YOUR 70.3 BASE
Ironman 70.3 Training: What Is Zone 2 / Endurance?
Ironman 70.3 Training: What Is Zone 3 / Tempo?
Ironman 70.3 Training: What Is Zone 4 / Threshold?
Ironman 70.3 Training: What Is Zone 5 / VO2 Max?
Ironman 70.3 Brick Training: 10 Key Sessions
Ironman 70.3 Bike Training: 10 Key Sessions
Ironman 70.3 Run Training: 10 Key Workouts
Ironman 70.3 Swim Training: 10 Key Workouts
Final Thoughts
Your first Ironman 70.3 isn’t just about finish lines. it’s about the journey, the discipline and discovering what you’re capable of. You’ll train on tired legs. You’ll juggle life, work and long rides. You’ll learn how to fuel, recover and push through moments when motivation fades. That’s the real test and it’s also where the real growth happens.
It’s not about being perfect. It’s about showing up, week after week and trusting the process. Every early morning, every session you didn’t want to do, every time you chose consistency over comfort, it all adds up. Ironman 70.3 is more than a race. It’s a decision to live with purpose, to train with intent and to prove to yourself that you can go longer, stronger and further than you thought possible.
So…what are you waiting for? Let’s go long.
Always consult with a medical professional or certified coach before beginning any new training program. The information provided is for educational purposes only and is not a substitute for personalized advice.
