Intermediate

Free 24-Week Ironman Training Plan

Ironman 140.6 (3.8 km swim / 180 km bike / 42.2 km run)

Duration
24
weeks
Weekly hours
12-18
hrs / week
Race time
10.5–16
hrs expected
Level
Intermediate
 

Twenty-four weeks is the standard Ironman plan for an intermediate athlete with previous 70.3 experience and an existing weekly training rhythm of eight to ten hours.

The plan does not start at 12-hour weeks. It ramps from your current load to a peak of around 18 hours during the highest-volume week, then tapers. Long bike rides progress from two and a half hours in week one to six and a half hours by week 20.

Long runs cap at two and a half hours — Ironman running is a fueling and pacing problem more than a duration problem, and longer runs in training carry more injury risk than fitness reward. Brick sessions on the weekend become the most important workout of the week from week 12 onwards.

If you have raced 70.3 and finished strong, this is your next plan.

What you need before you start

swim
1,500 m
continuous swim
bike
3 hours
continuous ride
run
60 min
continuous run

Training phases

1
Weeks 1–8
Aerobic base. Long-day endurance foundation.
2
Weeks 9–16
Sweet-spot and threshold bike, tempo runs, long swims.
3
Weeks 17–22
Peak — long bricks, longest ride and run, fueling rehearsal.
4
Weeks 23–24
Taper, race-week routine, glycogen loading.

Sample training week (Week 14)

Day Session
Mon Recovery swim 45 min Z1
Tue Bike — 90 min, 3 × 10 min threshold Z4
Wed Run — 60 min steady Z2 + strides
Thu Swim — 90 min long endurance Z2
Fri Easy spin 45 min + strength 45 min
Sat Long bike 5:30 + 30 min off-the-bike run
Sun Long run 2:00 progressive
Total ~13 hours

How to Read This Plan

Every TriWorldHub plan follows the same structure, so once you learn to read one, you can read them all.

Each triathlon training plan is divided into four phases that progress from general fitness to race-specific readiness. Inside each phase, weeks are organized into a microcycle pattern: typically three weeks of progressive load followed by one recovery week. This 3:1 pattern reflects how the human body usually adapts to endurance training.

Stress accumulates faster than recovery, so periodic deload weeks let the deeper adaptations (mitochondrial growth, capillary density, hormonal balance) catch up to the surface-level fitness.

Each daily session lists three things: the discipline (swim, bike, or run), a duration in minutes, and an intensity prescription.

Intensity is written in heart rate zones, power zones for the bike, or pace ranges for the run. When a session says “Bike – 75 min, 3 × 12 min sweet-spot,” it means a 75-minute ride that includes three twelve-minute intervals in the sweet-spot zone, with recovery between them.

Warm-up and cool-down are assumed. If the math says you have 36 minutes of work inside a 75-minute session, the remaining 39 minutes are easy spinning to bookend the effort.

Days without a session are real rest days, not “optional” days. Skipping rest is the most common mistake first-time plan-followers make. If you’re tempted to add a session, swap it for a mobility or strength block instead. The schedule already accounts for the volume your body can absorb.

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Training Intensity Zones Breakdown

Triathlon training works because it stresses different physiological systems on different days. Mixing those systems randomly leads to mediocre results. If you target them with precision, the results will be much better. Intensity zones are the language we use to target them.

The Four-Zone Model

Zone 1 – Recovery. Below 65% of FTP, below 65% of max heart rate, RPE 1–2. Conversational, nasal-breathing, easy. Used for active recovery rides, easy swims, and post-race spins. You should finish more relaxed than you started. Most athletes drift too high here and lose the recovery benefit.

Zone 2 – Aerobic endurance. 65–75% of FTP, 65–75% of max heart rate, RPE 3–4. The zone where mitochondria multiply, capillary density grows, and fat-burning enzymes develop. The majority of your weekly volume should live here, typically 70–80% of training time, even for advanced athletes. If you can hold a full sentence but not a paragraph, you’re in Zone 2.

Zone 3 – Tempo / Sweet-spot. 75–88% of FTP, 76–87% of max heart rate, RPE 5–6. The most time-efficient zone for raising the threshold without the recovery cost of full-threshold work. Bread-and-butter intervals for triathletes sustained 10–30 minute efforts that develop the engine you’ll race with.

Zone 4 – Threshold and above. 88%+ of FTP, 88%+ of max heart rate, RPE 7–9. Encompasses both lactate threshold (88–105% FTP, where lactate production matches clearance) and VO2 max efforts (106%+ FTP, short 3–6 minute repeats). Used in measured doses to raise your race ceiling. More is not better, too much Zone 4 burns deeper systems faster than they recover.

RPE – the backup gauge

Heart rate straps die, power meters drift, and GPS signal flakes out in the woods. Rate of Perceived Exertion (RPE) on a 1–10 scale is the analog backup that always works. Zone 2 is RPE 3–4. Zone 4 is RPE 7–8. If your devices and your RPE disagree, trust your RPE more than the number on the screen. Your body has been measuring effort longer than any sensor.

Periodization: Why Your Plan Changes Shape Over Time

A common beginner mistake is to do the same training every week and expect it to keep producing results. The body adapts to repeated stress and then plateaus.

Periodization solves this by changing the type and amount of stress in deliberate phases. Every TriWorldHub plan, regardless of distance, uses four phases:

  • Base phase builds the aerobic engine. Long, easy volume dominates. Intensity is low, duration is moderate-to-high. The goal is mitochondrial density, capillary growth, and the ability to burn fat efficiently. This is the slowest-feeling phase and the most important one, every later phase is built on this foundation.
  • Build phase adds intensity. Threshold and sweet-spot intervals replace some of the Zone 2 volume. Sessions get harder, weekly hours plateau or rise slightly. This is where speed becomes accessible without losing the endurance you built in the base phase.
  • Race-specific phase trains the exact pace, terrain, and conditions of your goal race. Long bricks (bike-into-run) become weekly. Open-water swim simulations appear. The plan begins to look like the race itself.
  • Peak and taper stage reduces volume by 30–50% while preserving intensity. The body sheds accumulated fatigue and arrives at the start line fresh. This phase feels strange because you’re training less, but you should feel sharper, not softer.

Discipline-Specific Fundamentals

Swim: Technique Compounds Faster Than Fitness

In running, fitness usually beats form. In swimming, the opposite is true.

A poorly streamlined swimmer with an aerobic engine of a champion will still get dropped by a technically clean swimmer with half the fitness.

Your plan prioritizes swimming technique drills, such as catch-up, finger-drag, side-kick, and scull, early and adds aerobic and speed work once your stroke holds together under fatigue. Open-water swim sessions appear in the race-specific phase to teach sighting, drafting, and pacing in a wetsuit.

Bike: The Discipline That Decides Your Race

The bike leg is the longest part of every triathlon and the place where most races are won or lost. Plans emphasize sustainable power output, not maximum power.

Long Zone 2 rides build the engine; sweet-spot and threshold intervals raise the ceiling. Aero positioning, cadence (target 85–95 rpm for most athletes), and fueling strategy are practiced on every long ride so they become automatic on race day.

Run: The Discipline That Hurts

Triathlon running is run-after-cycling running, which is a different sport than open marathon running. Plans use a high ratio of easy aerobic running with strategic threshold and VO2 work. Cadence (target 170–180 steps per minute), posture (slight forward lean from the ankles, not the waist), and breathing rhythm are reinforced session after session.

If you’re new to running, expect your first six weeks to feel disproportionately hard, the connective tissue adapts more slowly than the aerobic system.

Nutrition and Race-Day Fueling

Daily nutrition supports training, and your race-day fueling protects performance. They are different problems with different answers.

Daily Training Nutrition

Match your carbohydrate intake to your training volume. Easy days need fewer carbs; long days need many more.

A useful rule of thumb is 5–7 g of carbohydrate per kg of body weight per day during base phase, scaling up to 8–10 g/kg during the highest-volume weeks. Protein supports recovery and stays roughly constant at 1.6–2.0 g/kg per day. Dietary fat fills the rest of the energy needs and supports hormone function.

Race-Day Fueling

Race-day fueling targets vary by distance:

  • For sprint and Olympic races, hydration and a small amount of pre-race carbohydrate usually suffice.
  • For 70.3 and Ironman, you’ll need 60–90 g of carbohydrate per hour during the bike and run, plus 500–1,000 ml of fluid per hour depending on temperature.

Sodium replacement matters in hot conditions – 500–1,000 mg per hour for most athletes. Practice your race-day fueling on every long session. Race day is not the day to discover that the gel you bought makes you nauseous at 30 km.

Tapering: The Science of Arriving Fresh

Tapering is the most counterintuitive part of triathlon training.

After months of building, you spend the final two to three weeks doing less. Athletes new to the sport often resist this. They worry that less training means less fitness. The opposite is true: fitness is already in the bank by the time the taper begins. What needs to happen now is the dissipation of accumulated fatigue.

A correctly executed taper reduces total weekly volume by 30–50% while keeping intensity intact. You’ll do shorter intervals at the same paces you’ve been training, with more recovery days around them.

Sleep, hydration, and meal timing become more deliberate. By race week, you should feel sharper, slightly restless, and possibly anxious. These are normal signs that your body is over-recovered and ready to spend the fitness it has accumulated.

Common taper mistakes:

  • doing too much because you feel good,
  • doing too little because you feel flat,
  • panicking and adding a “last-minute confidence session,”
  • changing nutrition, trying new gear,
  • sleeping irregularly.

The most successful athletes treat the taper like a separate discipline that they practice with the same care as their interval sessions.

Race-Day Execution

A race plan is a written document with paces, watts, heart-rate caps, and fueling timestamps. Build it from the data you’ve already produced in training.

If your sustainable bike power for the goal duration is 195 watts, that is your race-day cap, not the 215 you might feel like pushing in the first 30 minutes when adrenaline is high. The athletes who blow up at the half-marathon mark almost always did so because of decisions made in the first 30 minutes of the bike.

The night before, lay out everything: wetsuit, goggles, swim cap, bike, helmet, shoes, race belt, nutrition for the bike, nutrition for the run, sunscreen, sunglasses.

Walk through the transitions mentally. Set two alarms. Eat a familiar breakfast three hours before the start. Arrive at the transition early enough that you’re not rushing. In a rush, it’s too easy to forget critical gear and start the race in a state of stress that takes 30 minutes to dissipate.

Common Triathlon Training Mistakes and How to Avoid Them

  • Skipping easy days. Easy days are where adaptation happens. If you can’t resist training hard every day, you’re not training, you’re grinding.
  • Ignoring strength work. Two short sessions per week prevent more injuries than any amount of stretching. Athletes who skip strength work are the athletes who develop plantar fasciitis, IT band syndrome, and lower back pain mid-plan.
  • Treating the plan as a maximum. Your plan is the prescription, not the target. Doing more can only lead to injury and overtraining.
  • New gear on race day. Race day is the wrong day for new shoes, a new wetsuit, a new gel flavor, or a new bike fit. Every variable on race day should be one you’ve tested in training.
  • Skipping the long brick. The single most race-specific session in your plan is the long brick in the race-specific phase. Missing it is the difference between holding your bike pace into the run and walking to the first aid station.

Frequently asked questions

How many weeks should I train for an Ironman?

24 weeks works for athletes with at least one 70.3 finish. First-time long-course athletes should use 30 weeks.

How many hours should I dedicate to training?

12–18 hours per week. Peak weeks hit 18; recovery weeks drop to 10.

When should I consider upgrading to the adaptive plan?

The free plan is fine if you respond to a consistent weekly structure and don’t mind doing your own load management. The adaptive plan is worth considering once your weekly hours exceed eight, your training-life balance gets complicated, or you have a specific race result you’re trying to hit. The adaptive plan adjusts to your daily HRV, recent training load, and RPE feedback. Basically, it changes tomorrow’s session based on what you actually did today, not on what the schedule was hoping you’d do.

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