Triathlon Coach | Last Updated: 2026
Most people who sign up for a 70.3 have no idea what they’re getting into. I don’t mean that as a knock — I mean the race sounds manageable on paper (half of an Ironman, surely that’s fine) and then week two of training hits and suddenly the math feels very different.
This guide is the training plan resource I wish I had when I started coaching athletes for the 70.3 distance. It covers everything: how long you actually need to train, what a week should look like at each phase, how to structure swim, bike, and run without destroying your body, and what most plans get wrong about nutrition and tapering.
Whether you’re building toward your first 70.3 or trying to finally crack a specific time goal, this is the framework.
What Is an Ironman 70.3?
An Ironman 70.3 — also called a Half Ironman — covers 70.3 total miles: a 1.2-mile open water swim, a 56-mile bike, and a 13.1-mile run (a half marathon). Athletes complete them consecutively, with transitions counted in the total race time.
The distance sits in a genuinely difficult middle ground. It’s long enough that you can’t fake fitness on race day, but short enough that race pace matters more than it does in a full Ironman. That combination is what makes 70.3 training tricky to get right.
Average finish times range from around 4 hours 30 minutes for competitive age groupers to 8 hours for first-timers. Most athletes who train consistently finish between 5:30 and 7:00.
How Long Does Ironman 70.3 Training Take?
The honest answer: 16 to 24 weeks for most athletes.
Here’s how to figure out where you land:
- 12 weeks — Only reasonable if you have a strong triathlon or endurance base already. You’ve done sprint and Olympic distance races and you’re currently training 8+ hours per week.
- 16 weeks — The sweet spot for athletes with some endurance background. You run or cycle regularly, can swim 1,500 meters without stopping, and have 8-12 hours per week to train.
- 20-24 weeks — The right timeline if you’re new to triathlon or coming from a mostly single-sport background. More time means more room to build aerobic base, which is where 70.3 races are actually won and lost.
What I see repeatedly: athletes underestimate how long the bike leg takes to develop. Running fitness transfers somewhat. Swimming fitness transfers somewhat. Cycling 56 miles at race pace is its own animal, and it takes months of consistent riding to handle it well.
The Prerequisites: Are You Ready to Start?
Before you begin any 70.3 training plan, you should be able to do these things comfortably (not fast, just comfortably):
- Swim: 800 meters without stopping
- Bike: 60-90 minutes at a moderate effort
- Run: 45-60 minutes, or 5-8 miles per week regularly
If you can’t hit those benchmarks yet, spend 4-6 weeks building to them before starting a structured plan. Trying to run a 16-week plan on zero base is how people get injured in week four.
The Ironman 70.3 Training Plan Framework
Every good 70.3 plan — regardless of length — follows the same basic periodization structure. Understanding that structure is more valuable than following any specific plan blindly.
Phase 1: Base Building (Weeks 1-6)
This is the least exciting phase and the most important one.
The goal is aerobic volume. Long, easy efforts that build your cardiovascular system, teach your body to use fat as fuel, and prepare your tendons and muscles for harder training later. Everything in this phase should feel sustainable — if you’re breathing hard, you’re going too fast.
Weekly training hours: 8-11 hours
Key sessions:
- Long easy bike ride (90 min to 2.5 hours, Zone 2 effort)
- Long easy run (60-90 min, conversational pace)
- 2-3 swim sessions focused on technique and distance
- No hard intervals yet
The biggest mistake athletes make in base phase: they go too hard. Zone 2 feels embarrassingly slow. Do it anyway. The athletes who follow this honestly in the first six weeks have a noticeably better race day.
Phase 2: Build Phase (Weeks 7-12)
Volume keeps increasing but now intensity enters the picture. This is where the training actually starts to feel like training.
Weekly training hours: 10-14 hours
Key sessions:
- Bike intervals: threshold efforts, over-unders, 20-minute FTP blocks
- Run tempo work: 20-40 minutes at 70.3 run pace (roughly your lactate threshold)
- Brick workouts: bike immediately followed by a run (more on these below)
- Swim sets with race-pace efforts
The psychological curve in build phase runs predictable: weeks 7-8 feel exciting, week 10 feels terrible, week 12 you start to feel like an athlete again. That dip around week 10 is normal and not a sign you’re doing anything wrong.
Phase 3: Race-Specific Phase (Weeks 13-18, if doing 20+ weeks)
Training volume peaks here. Long bricks. Race simulations. Nutrition practice under real load.
Weekly training hours: 12-16 hours
Key sessions:
- Race simulation brick: 3-4 hour ride at race effort + 30-45 min run
- Open water swim practice (if possible)
- Race-pace run intervals
- At least one 2+ hour ride per week
This is also when nutrition becomes non-negotiable. The reason most athletes blow up on the 70.3 run is inadequate fueling on the bike, not insufficient run fitness.
Phase 4: Taper (Final 2-3 Weeks)
Volume drops sharply. Intensity stays moderate. Most athletes hate this phase because they feel flat and question everything.
The taper is doing its job. Don’t add extra training.
Volume reduction: 30-50% in the final two weeks, 60-70% race week.
The Three Disciplines: How to Train Each One
Swim Training for Ironman 70.3
The 1.2-mile swim takes most age groupers between 35 and 55 minutes. It’s the shortest discipline by time, which is exactly why most athletes under-invest in it — and then spend the rest of race day recovering from a bad swim.
How often: 3 swims per week is ideal. 2 is acceptable. 1 is not enough.
What to focus on:
Technique first. A poor stroke at 1.2 miles is much more punishing than it is in a pool swim. If you have obvious mechanics issues — crossover stroke, dropped elbow, breathing problems — fix those before adding volume.
Open water skills matter. Pool fitness and open water confidence are not the same thing. Practice sighting (lifting your head to navigate without a lane line), swimming in a wetsuit, and swimming in close contact with other people. The 70.3 swim start can be chaotic.
A typical swim week in build phase:
- Session 1: Technique focus, 2,000-2,500 meters, drills + moderate sets
- Session 2: Threshold work, 2,500-3,000 meters, 200m and 400m intervals at race pace
- Session 3: Long continuous swim, 2,500-3,500 meters at easy effort
By race week, you should be comfortable swimming 2,500-3,000 meters in a single session without feeling it’s a major event.
Bike Training for Ironman 70.3
The bike leg is 56 miles and takes most athletes between 2.5 and 3.5 hours. It’s the longest part of the race by time, consumes the most energy, and sets up — or destroys — your run.
How often: 3 bike sessions per week. At least one long ride.
The key metric: FTP (Functional Threshold Power)
If you have a power meter, build your training around it. 70.3 race pace sits around 75-80% of your FTP. Going out harder than that almost always means walking the second half of the run.
If you don’t have a power meter, use heart rate or perceived effort. Race effort on the bike should feel “comfortably hard” — you can talk in short sentences but you’re clearly working.
A typical bike week in build phase:
- Session 1: Intervals, 60-75 min, threshold and VO2 work
- Session 2: Moderate ride, 90 min, steady Zone 3 effort
- Session 3: Long ride, 2.5-4 hours, mostly Zone 2 with some race-effort sections
Bike fit matters more for 70.3 than almost any other investment you can make. An hour on a bike that puts you in the wrong position is an hour of damage accumulating in your hips and lower back — and you feel it the moment you start running.
Run Training for Ironman 70.3
The half marathon (13.1 miles) comes after 2+ hours of swimming and 3+ hours of cycling. Your legs won’t feel like your legs. Training for this means not just building run fitness but building run fitness specifically in a pre-fatigued state.
How often: 3-4 run sessions per week.
The most important run workout you’re probably skipping:
Off-the-bike runs (brick runs). Running immediately after a long ride teaches your body the neurological pattern of “running when you feel like you can’t run.” Even 15-20 minutes off the bike is more valuable than an equivalent standalone run for 70.3-specific fitness.
A typical run week in build phase:
- Session 1: Tempo run, 40-50 min, 20-25 min at lactate threshold pace
- Session 2: Easy run, 45-60 min, completely aerobic
- Session 3: Long run, 75-90 min, mostly easy with last 15-20 min at race effort
- Session 4 (optional): Short brick run off the bike, 15-30 min easy
Your 70.3 run target pace should be 10-20 seconds per mile slower than your standalone half marathon pace. Start there and adjust based on how the bike goes.
Brick Workouts: The Most Important Sessions in Your Plan
Brick workouts — bike followed immediately by run, with no break — are the defining sessions of 70.3 training. Nothing else prepares you for the specific physical disorientation of starting to run after a long ride.
How to structure bricks through the plan:
- Base phase: Short bricks, 60-90 min ride + 15-20 min run, easy effort on both
- Build phase: Medium bricks, 90-120 min ride at race effort + 20-30 min run at race pace
- Race-specific phase: Long bricks, 3-4 hour ride + 30-45 min run, simulating race conditions
The brick run secret most plans ignore:
The first 10 minutes off the bike feel awful regardless of your fitness level. Your legs are doing something genuinely strange neurologically. Once you know this, you stop panicking about it. Keep your pace easy for the first mile, then settle into your target effort. Almost every athlete feels dramatically better by mile 2.
70.3 Nutrition: Why Most Athletes Get This Wrong
The 70.3 run leg is where races are lost. In most cases, the cause isn’t run fitness — it’s under-fueling on the bike.
The basic math:
A 70.3 burns somewhere between 3,000 and 4,500 calories depending on your size and pace. You cannot replace all of that during the race, and you’re not trying to. But you do need to take in enough carbohydrate to avoid running out of glycogen on the run.
Target: 60-90 grams of carbohydrate per hour on the bike.
Start fueling within the first 20-30 minutes of the bike leg, before you feel hungry. By the time you feel hungry or depleted, you’re already behind and it’s very hard to recover.
Practical fueling during training:
Practice race nutrition in training, especially in long bricks. Your gut needs to learn to process carbohydrate while working hard. Athletes who try new nutrition products or amounts on race day frequently have GI problems on the run.
Good sources: sports gels, chews, rice cakes, bananas, sports drink. Test everything in training.
Hydration: 16-24 oz of fluid per hour on the bike in normal conditions. More in heat. Plain water on the run; use race course nutrition or what you’ve trained with.
Pre-race: High-carb dinner the night before. Light carb-focused breakfast 2-3 hours before the swim start. No new foods.
Sample Ironman 70.3 Training Weeks
Sample Week — Base Phase (Week 4 of 16)
| Day | Session |
|---|---|
| Monday | Rest or optional easy swim (1,500m technique focus) |
| Tuesday | Bike: 60 min easy Zone 2 + Run: 20 min easy off bike |
| Wednesday | Swim: 2,500m moderate (technique + steady sets) |
| Thursday | Run: 50 min easy Zone 2 |
| Friday | Rest |
| Saturday | Long bike: 2.5 hours easy (Zone 2) |
| Sunday | Long run: 70 min easy + Swim: 30 min optional |
Total: ~9-10 hours
Sample Week — Build Phase (Week 10 of 16)
| Day | Session |
|---|---|
| Monday | Rest |
| Tuesday | Swim: 3,000m with intervals + Run: 40 min with 20 min tempo |
| Wednesday | Bike: 75 min with threshold intervals (3×10 min at FTP) |
| Thursday | Run: 60 min easy + Swim: 2,500m steady |
| Friday | Rest or easy 30 min swim |
| Saturday | Long brick: 3 hr ride at race effort + 25 min run at race pace |
| Sunday | Long run: 80 min (easy, aerobic) |
Total: ~12-13 hours
Sample Race Week (Final Week)
| Day | Session |
|---|---|
| Monday | Rest |
| Tuesday | Swim: 1,500m easy + short run 20 min |
| Wednesday | Bike: 45 min easy with 3×5 min at race effort |
| Thursday | Easy run: 20-25 min, short strides |
| Friday | Rest, travel, registration |
| Saturday | Easy 10 min swim in race venue water, 15 min easy spin, 10 min walk/jog |
| Sunday | RACE DAY |
Common Mistakes in 70.3 Training
Training too hard too early. Base phase should feel slow. If week two feels hard, you’ll be destroyed by week ten.
Neglecting the bike. Athletes from running backgrounds almost always under-develop on the bike. The bike leg is where you set up the run — or ruin it.
Skipping brick runs. There’s no substitute. Do them.
Cramming volume in the final weeks before the race. The fitness you build in week 15 does not show up on race day. It shows up six weeks later. Build your fitness earlier and trust the taper.
Ignoring nutrition until race week. Your gut is trainable. Train it. If you’re only practicing fueling in your last few long sessions, you’re going into race day with a gut that’s never processed 60g of carbs per hour while working at 70.3 effort.
No sleep. This is where most athletes steal training time from. Adaptation happens during recovery. Eight hours of sleep is more valuable than an extra easy session.
What to Do the Week Before Your 70.3
Taper anxiety is real and it lies to you. Your legs feel flat because your glycogen stores are full, not because you’re losing fitness. The heavy, tired feeling in weeks 13-15 disappears and race day you feel fast.
Final week checklist:
- Confirm your race kit is complete (wetsuit, helmet, race number, nutrition)
- Drive or review the bike and run courses
- Practice your transitions at least once
- Eat consistently and high-carb the final two days
- Sleep aggressively — the night before the race you might sleep poorly due to nerves, so bank sleep the two nights before
- Get to the race venue early on race morning
Race Day Strategy
Swim: Start conservatively. Even if you feel great, the first 200 meters will feel chaotic. Let the pack thin, find open water, and settle into your rhythm. Sight every 6-10 strokes.
T1: Slow is smooth. A 30-second error in transition is recoverable. A panic in transition costs minutes.
Bike: Resist the urge to go hard on the first 10-15 miles. Everyone feels good early. Your target power or effort should be steady, not building. Eat within 20 minutes of starting the bike. Eat again every 20-30 minutes after that.
T2: Quick but calm. Put your legs through a brief mental reset.
Run: The first mile is always the worst. Keep the first mile 10-15 seconds slower than target and then settle in. Don’t let the “I feel great” of the first half mile trick you into banking time you’ll pay back with interest.
The honest truth about 70.3 race pacing: Go out 10% more conservatively than you think you should. Almost every athlete who has a great 70.3 race says they held back early. Almost every athlete who blows up says they felt great at the start.
Frequently Asked Questions
How many hours per week does Ironman 70.3 training require?
Most athletes train between 8 and 15 hours per week for a 70.3. Beginners on a 20-week plan typically build from 6-7 hours in the early weeks to 12-14 hours at peak volume. Intermediate athletes usually train 10-14 hours per week at peak. The final two weeks drop significantly as part of the taper.
Can I train for an Ironman 70.3 while working full-time?
Yes — most 70.3 athletes work full-time. The key is making the most of the time you have. Early morning workouts, combining sessions intelligently (like swim in the morning and run in the evening), and being strategic about which sessions to prioritize when life gets in the way. The long Saturday brick is usually non-negotiable.
Is a 12-week Ironman 70.3 training plan enough?
For most people, no. Twelve weeks is feasible only if you have a strong existing base — you’re already training 8+ hours per week across the three disciplines and have recent triathlon experience. Otherwise, 16-20 weeks gives you the time to build real aerobic fitness rather than just surviving the race.
What should my training plan include each week?
A complete 70.3 training week includes at least two swims, three bike sessions (one long), and three runs (one long, one with some quality, one easy), plus at least one brick workout per week during build and race-specific phases. Total sessions: 8-10 per week at peak volume.
How do I balance triathlon training without overtraining?
Overtraining in 70.3 prep usually comes from too much intensity, not too much volume. Keep 70-80% of your training at genuinely easy effort (you can hold a conversation). Include one full rest day per week. Every 3-4 weeks, cut volume by 20-30% for a recovery week. Sleep 7-9 hours.
What is the hardest part of Ironman 70.3 training?
Most athletes say the run after the bike. It’s not a standalone half marathon — it’s a half marathon on legs that have already done 2.5-3.5 hours of work. That’s why brick workouts and race-specific fueling are the two things you can’t skip.
Do I need a coach for Ironman 70.3 training?
Not necessarily, but structured coaching helps if you’ve plateaued, if you have a specific time goal, or if you struggle with accountability and plan adherence. A good plan you follow consistently beats a perfect plan you half-follow.
Final Thoughts
A 70.3 is a serious undertaking and training for one properly is one of the more satisfying athletic projects you can take on. The distance rewards consistency, patience, and smart pacing far more than raw fitness or heroic training weeks.
The athletes I’ve coached who have their best races are almost always the ones who built their base honestly, practiced nutrition in training, did their brick workouts, and trusted the taper. None of that is complicated. Most of it just requires showing up to the boring sessions.
The race itself is a celebration of the work. Do the work first.
Looking for a done-for-you plan? Check out our Ironman 70.3 training plan PDFs — 12, 16, and 20-week versions available for beginner, intermediate, and advanced athletes.
Related: Half Marathon Training Plan
