Training for a Half Ironman can feel overwhelming when you first try to combine swimming, cycling and running in the same week. This beginner-friendly 20-week plan turns the challenge into a clear progression, with enough training to build endurance and enough recovery to keep the process sustainable.
The plan is designed for first-time 70.3 athletes who want to reach the start line prepared to complete the 1.9 km swim, 90 km bike and 21.1 km run. It gradually extends your long sessions, introduces brick workouts, develops race-specific pacing and finishes with a structured taper.
Most beginners can prepare for a Half Ironman in 20 weeks when they already have a basic fitness foundation. Expect roughly 6 to 7 hours per week at the beginning, building toward 10 to 11 hours in the biggest weeks. The standard rhythm is two swims, three bike sessions and three runs, with every fourth week reduced for recovery.
Start this plan when you can swim at least 400 metres with short breaks, ride for 60 to 90 minutes and run continuously for around 30 minutes. You do not need to be fast, but you should be able to train consistently without pain.
This is a general training framework rather than individual medical advice. Reduce the workload when pain changes your movement, fatigue continues to worsen or normal recovery markers remain unusually poor. Athletes with medical concerns or a significant injury history should seek qualified guidance before beginning.
What distance are you training for?
A Half Ironman—commonly called a 70.3—combines a 1.9 km swim, a 90 km bike and a 21.1 km run. The number 70.3 represents the total distance in miles.
The goal is not to become equally fast in all three sports. It is to become technically comfortable in the water, durable on the bike and controlled enough to begin the half marathon with energy still available.
What should you be able to do before week 1?
A 20-week plan provides enough time to build substantial endurance, but it is not a couch-to-70.3 programme. A small starting base lets the plan progress without forcing large jumps in training load.
- Swim 400 metres using short rests when necessary
- Complete a comfortable 60- to 90-minute bike ride
- Run or use a run-walk strategy for approximately 30 minutes
- Train on five or six days during a normal week
- Use basic swim, bike and run equipment safely
- Recover from ordinary aerobic sessions within one or two days
Athletes below these starting points can still complete a Half Ironman, but an additional four to eight weeks of general base training is usually a better approach than forcing the early weeks.
How the 20-week plan is structured
The programme uses three progressive training weeks followed by a lighter recovery week. This pattern gives you repeated opportunities to build fitness, absorb the workload and begin the next block with less accumulated fatigue.
| Phase | Weeks | Main goal | Training emphasis |
|---|---|---|---|
| Foundation | 1–4 | Establish a repeatable routine | Technique, easy endurance and short bricks |
| Endurance | 5–8 | Extend sustainable training time | Longer rides, longer runs and steady swimming |
| Build | 9–12 | Add controlled quality | Tempo work, race-effort blocks and stronger bricks |
| Race specific | 13–17 | Prepare for the demands of 70.3 racing | Fueling, pacing, open water and long combinations |
| Taper | 18–20 | Reduce fatigue while maintaining readiness | Lower volume, short race-effort work and recovery |
A practical weekly schedule
The exact days can be moved to match work and family commitments. Preserve the logic of the schedule: avoid placing every hard session together, keep the long ride and long run separated when possible, and protect at least one genuinely light day.
Rest or mobility
Use a complete rest day or 15 to 25 minutes of easy mobility and core work.
Bike quality + short brick
Complete the week's main bike intervals, followed by a relaxed 10- to 25-minute run.
Swim + easy run
Focus on swim technique, then complete an easy aerobic run later in the day.
Endurance bike + swim
Ride at a controlled aerobic effort and complete the second swim of the week.
Easy run + optional strength
Keep the run comfortable. Add a short strength session only when it does not affect the weekend.
Long ride and long run
Place the long ride on Saturday and the long run on Sunday, or reverse them when recovery is better that way.
When life interrupts the plan, protect one swim, the long ride, the long run and one additional bike session. Do not cram missed workouts into the following days.
Training intensity explained
Beginners do not need complicated testing to follow the plan. You can use perceived effort and the talk test, then add heart rate, pace or cycling power when you already understand those tools.
| Effort | RPE | Talk test | Typical use |
|---|---|---|---|
| Recovery | 2–3/10 | Conversation is effortless | Easy swims, spins and short recovery runs |
| Easy aerobic | 3–4/10 | Full sentences are comfortable | Most long rides, long runs and endurance work |
| Steady / race effort | 5–6/10 | Short sentences remain possible | 70.3-specific bike blocks and controlled runs |
| Tempo | 6–7/10 | Only short phrases | Moderate intervals and sustained quality work |
| Hard | 8/10 | Talking is difficult | Short intervals used sparingly |
Around 80 percent of beginner training should feel easy or comfortably steady. The purpose of harder work is to support endurance—not to make every week feel like a race.
The complete 20-week Half Ironman training plan
Session counts include brick runs as run sessions. Weekly totals are approximate and can vary by 30 to 45 minutes depending on swim speed, warm-ups and transitions. Recovery weeks deliberately reduce both volume and intensity.
| W | Swim | Bike | Run | Long bike | Long run | Approx. total | Main focus |
|---|---|---|---|---|---|---|---|
| 1 | 2 | 3 | 3 | 1:30 | 0:45 | 6:15 | Routine and relaxed technique |
| 2 | 2 | 3 | 3 | 1:45 | 0:50 | 6:45 | Aerobic consistency |
| 3 | 2 | 3 | 3 | 2:00 | 0:55 | 7:15 | First regular brick run |
| 4 | 2 | 2 | 2 | 1:20 | 0:40 | 5:30 | Recovery and technique |
| 5 | 2 | 3 | 3 | 2:15 | 1:00 | 7:30 | Extend easy endurance |
| 6 | 2 | 3 | 3 | 2:30 | 1:05 | 8:00 | Introduce controlled tempo |
| 7 | 2 | 3 | 3 | 2:40 | 1:10 | 8:30 | Longer ride and 20-minute brick |
| 8 | 2 | 2 | 2 | 1:45 | 0:50 | 6:15 | Recovery and skill work |
| 9 | 2 | 3 | 3 | 2:50 | 1:15 | 8:45 | Begin race-effort bike blocks |
| 10 | 2 | 3 | 3 | 3:00 | 1:20 | 9:30 | Fuel every long session |
| 11 | 2 | 3 | 3 | 3:10 | 1:25 | 10:00 | Long brick progression |
| 12 | 2 | 2 | 2 | 2:00 | 1:00 | 7:30 | Recovery and pacing review |
| 13 | 2 | 3 | 3 | 3:15 | 1:30 | 10:15 | Race-specific endurance |
| 14 | 2 | 3 | 3 | 3:20 | 1:35 | 10:45 | Open water and race nutrition |
| 15 | 2 | 3 | 3 | 3:30 | 1:40 | 11:15 | Peak endurance week |
| 16 | 2 | 2 | 2 | 2:15 | 1:10 | 8:15 | Recovery and equipment check |
| 17 | 2 | 3 | 3 | 3:15 | 1:30 | 10:30 | Final race rehearsal |
| 18 | 2 | 3 | 3 | 2:15 | 1:10 | 8:30 | Begin taper |
| 19 | 2 | 2 | 3 | 1:30 | 0:45 | 6:30 | Freshness with short race-effort work |
| 20 | 2 short | 2 short | 2 short | Race | Race | 5–7 incl. race | Race week |
Durations are shown as hours:minutes. Adjust the total slightly when your starting fitness, recovery capacity or available training time differs from the assumed beginner profile.
Weeks 1–4: Build the foundation
The first block is about making training normal. Keep nearly everything comfortable and finish sessions feeling that you could have continued. Technique improvements are especially valuable in swimming because greater efficiency reduces the energy cost of race day.
Relaxed technique
Use short repetitions such as 8 × 50 m and 6 × 100 m with enough rest to maintain good form.
Cadence and control
Ride mostly easy and include several one- to three-minute cadence changes without turning them into maximal efforts.
Durability first
Use easy running or planned walk breaks. Consistency matters more than pace.
Example quality session
Bike for 60 minutes with 6 × 3 minutes at a steady, controlled effort and 3 minutes easy between repetitions. Follow with a 10-minute easy brick run in week 3.
Weeks 5–8: Extend your endurance
The second block gradually makes the long ride and long run more substantial. Do not increase the intensity of every workout simply because your fitness is improving. The added duration is already a meaningful training stress.
Example quality sessions
- Bike: 3 × 8 minutes at tempo effort with 4 minutes easy recovery
- Run: 3 × 6 minutes at controlled steady effort with 3 minutes easy
- Swim: 3 × 400 m relaxed and even, with 45 to 60 seconds rest
- Brick: 15 to 20 minutes easy after the long ride
Reduce volume even when you feel good. Recovery weeks are not lost training; they are where the previous workload becomes usable fitness.
Weeks 9–12: Add controlled quality
You now begin spending more time near a sustainable Half Ironman effort. These sessions should feel purposeful but repeatable. Avoid using race-effort blocks as hidden time trials.
3 × 15 minutes at 70.3 effort
Warm up for 15 minutes, ride three controlled 15-minute blocks with 5 minutes easy between, then cool down.
2 × 15 minutes steady
Run easily for 15 minutes, complete two 15-minute steady blocks with 5 minutes easy, then finish relaxed.
5 × 300 metres
Swim each repeat at a controlled rhythm with 30 to 45 seconds rest. Keep the final repetition technically strong.
Begin testing your race nutrition during every ride longer than two hours. The exact intake is individual, but many athletes practise approximately 60 to 90 grams of carbohydrate per hour on the bike and a smaller, tolerable amount on the run. Build toward higher intake gradually rather than changing everything in one session.
Weeks 13–17: Become race specific
The final build block should make race day familiar. Use the equipment, nutrition, hydration and pacing strategy you expect to use in the event. Open-water practice becomes increasingly valuable when it is safe and available.
-
Practise race-position comfort
Spend controlled time in your intended riding position. Neck, shoulder, hand and saddle comfort matter as much as fitness during a 90 km ride.
-
Use long race-effort blocks
Include 2 × 30 minutes or 3 × 25 minutes at planned 70.3 effort within selected long rides.
-
Extend one brick run
Build one or two brick runs to 35 or 45 minutes, starting easier than you think necessary.
-
Rehearse transitions
Practise the order of your equipment and the first minutes of both cycling and running.
Your final race-specific workout should increase confidence, not require a week of recovery. A useful rehearsal might include a 2.5- to 3-hour ride with race-effort blocks followed by 30 minutes of controlled running—not a full 70.3 performed at maximum effort.
Weeks 18–20: Taper without losing rhythm
Fitness is already built. The taper reduces accumulated fatigue while preserving coordination and confidence. Volume falls, but you continue swimming, cycling and running regularly.
Frequency and short race-effort work
- Short, familiar sessions
- Several brief race-effort intervals
- Normal meal timing and hydration
- Consistent sleep routines
Fatigue-producing training
- Last-minute long workouts
- Unfamiliar hard intervals
- Heavy strength training
- New shoes, saddles or nutrition products
How to approach the swim sessions
Two swims per week can be enough to finish a Half Ironman when they are consistent and technically focused. A third short swim is useful for athletes who are uncomfortable in the water or recover quickly from swimming.
Technique and shorter repeats
Use drills sparingly, then repeat 50- to 200-metre efforts while maintaining relaxed breathing and body position.
Endurance and race rhythm
Build toward longer sets such as 3 × 500 m, 2 × 800 m or a controlled continuous swim.
- Practise sighting before open-water sessions
- Learn to breathe comfortably to both sides, even if one side remains preferred
- Test your wetsuit before race week
- Swim with others in a safe environment before your first mass start
- Focus on calm rhythm rather than aggressive early speed
Why the bike receives the most training time
Cycling is the longest discipline and has a major effect on the run. A slightly stronger bike ridden conservatively is often more valuable than a fast bike split that turns the half marathon into survival.
Build enough cycling durability that 90 km is no longer an exceptional distance, then choose an effort that protects your ability to run.
Your three weekly rides normally serve different purposes: one controlled quality session, one aerobic endurance ride and one long ride. The long ride is also the main environment for practising nutrition, hydration and equipment.
How to build the run safely
Running creates more impact than swimming or cycling, so progression should be conservative. Three shorter, repeatable runs are often safer and more effective than two oversized sessions.
The longest run in this plan peaks at around 100 minutes. You do not need to run a standalone half marathon before race day. The goal is to develop enough durability while avoiding fatigue that compromises cycling and swimming.
Planned walk breaks can reduce impact, improve fueling and keep effort under control. A structured run-walk strategy is not failure; for many first-time athletes it is the fastest route to a steady overall result.
How often should beginners do brick workouts?
Short brick runs can appear almost every week once your body tolerates them. Most should last only 10 to 25 minutes and remain easy. Their purpose is neuromuscular familiarity, not extra exhaustion.
75-minute bike + 15-minute run
Ride easily for 45 minutes, complete 3 × 6 minutes at a steady effort with 3 minutes easy, then transition into a relaxed 15-minute run. Keep the first five minutes deliberately slow.
Longer bricks become useful in the race-specific phase, but they should not replace the separate long run. Use our Half Ironman brick workout guide for 70.3-specific session progression, our general brick guide for the fundamentals, and How to Run After Cycling for off-bike pacing and form.
Do you need strength training?
One short strength session per week can improve resilience without becoming a fourth sport. Keep the exercise selection stable and avoid training to failure.
- Split squats or step-ups for single-leg strength
- Romanian deadlifts or hip hinges for posterior-chain strength
- Calf raises for lower-leg durability
- Rows and shoulder-stability exercises for swimming posture
- Side planks, carries or dead bugs for trunk control
Use two or three sets of controlled repetitions and finish with good technique still available. Reduce strength volume during the final race-specific weeks and remove heavy lifting during the taper.
Practise nutrition throughout the plan
Your ability to absorb carbohydrate and fluid is trainable. Begin with manageable amounts during long rides, then gradually approach the intake you intend to use on race day.
| Workout | What to practise | Main objective |
|---|---|---|
| Long ride | Carbohydrate, fluid, sodium and bottle placement | Build a repeatable race system |
| Brick | The transition from bike fueling to run fueling | Reduce stomach surprises |
| Long run | Small, tolerable carbohydrate and fluid amounts | Find products that work while running |
| Race rehearsal | Breakfast, timing, products and quantities | Make race morning familiar |
Use the same products, concentrations and carrying method in training. Even a well-designed nutrition strategy can fail when it has never been tested at race intensity.
Recovery rules that keep the plan working
- Keep easy sessions genuinely easy
- Eat enough to support the workload rather than constantly dieting
- Prioritise sleep before adding optional sessions
- Use recovery weeks even when motivation is high
- Separate the hardest bike and run sessions when possible
- Track persistent pain, mood changes and declining performance
Missing one workout has little effect. Repeatedly completing hard sessions while under-recovered has a much larger effect. Consistency is created by making sensible decisions on imperfect weeks.
How to adjust the plan
When swimming is your weakness
Add a short third swim of 25 to 40 minutes and remove optional strength or a short recovery session if necessary.
When cycling is your weakness
Keep all three rides and shorten one easy run rather than sacrificing the long ride.
When running is your weakness
Do not immediately add a fourth run. First make the three planned runs consistent and pain-free.
When time is limited
Reduce warm-ups, optional strength and recovery sessions before removing the long ride or long run.
When a session is missed, continue with the plan. Adding it to the following day can turn a small disruption into several days of poor recovery.
Your final race rehearsal
Complete the final major rehearsal in week 17, approximately three weeks before race day. Use your intended equipment, breakfast timing, nutrition products and pacing approach.
3:15 bike + 30-minute brick run
Ride the first hour easily, complete 2 × 35 minutes at planned 70.3 effort with 10 minutes easy between, then finish controlled. Transition into a 30-minute run: 10 minutes very easy, 15 minutes at planned race effort and 5 minutes easy.
The workout should confirm decisions rather than introduce new ones. Note what you ate, drank and wore, where equipment was placed and how your stomach and legs felt during the run.
Race-week schedule
| Day | Session | Purpose |
|---|---|---|
| Monday | Rest or 20-minute easy swim | Recover and reset |
| Tuesday | 45-minute bike with 3 × 3 minutes at race effort | Maintain bike rhythm |
| Wednesday | 30-minute easy run with 4 short strides | Maintain run coordination |
| Thursday | 30-minute swim with a few short race-effort repeats | Water confidence |
| Friday | Rest, travel and equipment preparation | Reduce stress |
| Saturday | 10–20 minutes in each available discipline, all easy | Check equipment and stay loose |
| Sunday | Race day | Execute the plan |
Move the days when your race is held on a different weekday. The sessions are deliberately short and should leave you more energetic, not less.
Beginner race-day pacing
-
Start the swim calmly
Use the first minutes to establish breathing and space. A slightly slower start is easier to correct than early panic.
-
Hold back on the first half of the bike
Let other athletes pass. Focus on smooth power, nutrition and an effort that feels almost too controlled.
-
Begin fueling early
Follow the tested schedule before hunger or thirst becomes obvious.
-
Run the first kilometres below target effort
The legs usually feel strange after cycling. Give them time to settle before deciding how strong you feel.
Common beginner training mistakes
Turning every ride into a test
Hard group rides and personal records can undermine the long-term consistency the plan requires.
Increasing volume and intensity together
When the long sessions grow, keep most other training controlled.
Skipping recovery weeks
Fitness does not disappear because one week is lighter. Fatigue is what should disappear.
Neglecting swim technique
More metres with poor form can reinforce inefficiency and increase frustration.
Waiting to practise nutrition
Race-day fueling should be the result of repeated training experiments.
Trying new equipment during the taper
Late changes to shoes, saddles, wetsuits or position create unnecessary risk.
Frequently asked questions
Can a beginner train for a Half Ironman in 20 weeks?
Yes. Twenty weeks is realistic for a healthy beginner who already has a small base in all three disciplines and can train consistently. Completely untrained athletes usually benefit from additional foundation weeks first.
How many hours per week does the plan require?
The plan starts at approximately 6 to 7 hours per week, builds toward peak weeks of roughly 10 to 11 hours and reduces during recovery weeks and the taper.
How many times should I swim, bike and run?
The standard structure uses two swims, three bike sessions and three runs. Some sessions are short and paired on the same day, and one run is often a brick.
Can I complete the plan with only six training days?
Yes. Use one complete rest day and combine compatible sessions, such as a swim with an easy run or a bike with a short brick run.
How long should my longest bike ride be?
The longest ride in this plan is approximately 3.5 hours. Slower riders can occasionally use distance as an additional guide, but there is no need to complete the full 90 km at race effort before race day.
How long should my longest run be?
The plan peaks at around 100 minutes. This provides useful endurance without the recovery cost of repeatedly running a full half marathon in training.
Should I do a brick workout every week?
Frequent short bricks are useful once your body tolerates them. Keep most to 10–25 easy minutes and use only a small number of longer race-specific bricks.
Can I move the workouts to different days?
Yes. Keep the overall balance and avoid stacking the hardest bike, hardest run and longest sessions without adequate recovery.
What should I do after missing a week?
Do not compress the missed work into the next week. Resume with reduced volume, repeat the previous week when necessary and rebuild gradually after illness or a longer interruption.
Should I train by heart rate, pace, power or perceived effort?
All can work. Perceived effort is sufficient for beginners, while heart rate and power add useful control when your zones are tested and understood. Avoid letting one number override obvious fatigue or poor conditions.
Do I need a triathlon bike?
No. A well-fitted road bike in reliable condition is enough for training and racing. Comfort, handling, nutrition storage and mechanical reliability matter more than owning a dedicated time-trial bike.
Can I use this plan for an Ironman?
No. A full Ironman requires a substantially longer progression and more endurance volume. Use our 40-week Ironman training plan for that distance.
Final verdict
A successful first Half Ironman is built through months of ordinary, repeatable training rather than a handful of heroic workouts. This 20-week plan gradually develops each discipline while keeping the bike, run, swim, brick, recovery and taper demands in balance.
Follow the progression, keep easy training easy, practise your nutrition and make adjustments before fatigue becomes a crisis. Arriving slightly undertrained but healthy is far more useful than arriving highly trained and exhausted.
Consistency beats perfection. Complete the sessions you can recover from, learn from each long workout and protect your ability to train again next week.
This plan is a general educational framework and should be adjusted to the athlete. Images are hosted on the Triathlon Loop Shopify CDN. Inline photographs are credited to Farzona Comnas, Tuvalum and Kaan Durmuş via Pexels.
If you want the entire build organized week by week, use our beginner half-distance triathlon training plan.
Compare all available triathlon, running and cycling training plans before choosing your next schedule.
This schedule gives you the daily work. For the reasoning behind weekly volume, discipline balance, long-session targets, bricks, fueling and tapering, read our complete guide to training for a Half Ironman.
