How many weeks to prepare for a Half-Ironman 70.3?

A 16-week 70.3 Ironman plan suits an athlete with Olympic experience. If you're new to long distance, a 20-week Half-Ironman plan is more cautious.

How many hours per week for a Half-Ironman plan?

Average weekly volume is 10 to 13 hours, with peaks at 15–16 hours during key weeks (often 3 to 5 weeks before the race).

How many long bike rides should I plan?

At minimum 8 long bike rides of 3h to 4h30 across the entire plan, ideally with one or two rides at 5h simulating race conditions for slower athletes.

Should I do a test Half-Ironman before the race?

Not a full Half, but a 'big weekend' simulation 4 weeks out is very useful: 4h bike followed by 30 min run on Saturday, then trail / long run Sunday.

What time should I aim for in a Half-Ironman 70.3?

For a first-time finisher: between 5h30 and 7h00. An intermediate athlete targets 5h to 5h30. The very best amateurs go under 4h45. Everything depends on the course, the heat and your race nutrition.

What nutrition for a Half-Ironman?

Target: 60 to 90 g of carbs per hour, 500 to 800 ml of fluid depending on heat. This strategy must be tested in long training, not discovered on race day.

Do I need a smart trainer to prepare for a Half-Ironman?

Yes, strongly recommended. Over 16 weeks, the smart trainer (Zwift, Wahoo, Tacx) secures key threshold and sweet-spot sessions, regardless of weather. In winter or cold climates, it's flat-out essential to maintain bike volume.

TriCoach AI Guide·Updated April 2026

Half-Ironman 70.3 plan: adjustable program, all levels

The Half-Ironman 70.3 (1.9 km swim, 90 km bike, 21.1 km run) marks the entry into long-distance triathlon. This 70.3 plan, adjustable from 12 to 16 weeks depending on your level (beginner, intermediate, advanced), extends if you have more lead time before race day. It details the progression, weekly volume, key sessions and nutrition to finish, or perform, on the distance.

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My Races

Triathlon ValleyfieldA

Aug 17, 2026 · Sprint

1:08:31

Swim

14:25

1:59

Bike

32:02

2:36

Run

17:29

Overall

#19 / 311

Age Group

#2 / 18

Triathlon DuchesnayAug 2, 2025 · Sprint

1:08:16

Ironman Sables d'OlonnesJun 22, 2025 · Ironman

11:57:37

How many weeks do you actually need?

Minimum 70.3 plan durations by level. If you're new to long course, aim for the upper end: your plan stretches when you have more lead time.

Distance	Beginner	Intermediate	Advanced
Sprint	8 wk	6 wk	6 wk
Olympic	12 wk	8 wk	8 wk
Half-Ironman 70.3	16 wk	12 wk	12 wk
Ironman	24 wk	20 wk	16 wk

Adjustable plan: TriCoach AI resizes the base and build phases based on the time available before race day.

Sample week: Half-Ironman 70.3 plan

A mid-specific-phase week of a 16-week 70.3 plan, around 12 weekly hours.

Swim: 3 sessions

· Mon: Technique 2,800 m
· Wed: Threshold 8×200 m
· Fri: Continuous 3,200 m

Bike: 3 sessions

· Tue: Sweet-spot 4×12 min
· Thu: Tempo 1h30
· Sat: Long 4h + 20 min run

Run: 3 sessions

· Tue: Brick 20 min 70.3 pace
· Thu: Intervals 5×1 km
· Sun: Long run 1h45

Volume and periodization over 16 weeks

Phase	Weeks	Weekly volume	Focus
Base	1–5	9–11 h	Base endurance, bike strength
Specific	6–12	12–15 h	Sweet-spot, long bricks, nutrition
Taper	13–16	7–10 h	Freshness, 70.3 pace reminders

Half-Ironman 70.3 specifics

The 70.3 is a 4h to 7h effort. That changes everything: nutrition becomes a pillar of performance, thermal management too. Poor bike nutrition is paid dearly on the half-marathon.

Bricks become long: 4h bike + 20 to 30 min of running at 70.3 pace must be done several times in the specific phase to teach the body to run on pre-fatigued legs.

Strength training & mobility

Over 16 weeks, strength protects against injury and improves bike posture (key to holding 90 km in aero). 2 strength sessions + 1 mobility session per week is the target. TriCoach AI integrates them into your plan.

2× strength (45 min)

Focus posterior chain, core, aero posture. Squats, deadlift, planks, single-leg work. Volume reduced in the specific phase.

1× yoga / mobility (30 min)

Hip opening (critical for 21 km after 90 km of bike), shoulder flexibility for swimming, back.

5 common mistakes on a Half-Ironman plan

Insufficient bike volume: without regular 4h+ rides, the final half-marathon turns into a nightmare.
Discovering nutrition on race day: every gel, every drink must have been tested.
Too much intensity, not enough endurance: on the 70.3, aerobic base pays.
Skipping recovery weeks: chronic fatigue is the biggest enemy over 16 weeks.
Following a frozen plan that ignores life: a 16-week Half-Ironman plan must adapt to your unexpected events.

Why your 70.3 plan must adapt to your life

16 weeks is long. Vacations, work travel, seasonal viruses, weather: it will all happen. A frozen Half-Ironman PDF plan won't survive. You accumulate missed sessions and lose confidence.

TriCoach AI readjusts your plan every week based on what you actually completed, your fatigue and your progression. Your key sessions (long bricks, long bike rides) are protected as a priority.

Create my personalized 70.3 plan

Equipment & training conditions

16 weeks is long, and your gear must keep up. TriCoach AI adapts each session to your available equipment and your seasonal access.

Swim

· Pool 25 m or 50 m (3×/week)
· Wetsuit for open water
· Summer: 1 to 2 open water swims/week
Winter: focus on pool and dry-land technique

Bike

· Tri bike or road bike with extensions
· Smart trainer essential (Zwift, Wahoo, Tacx)
· Power meter strongly advised
Cold climate: smart trainer for 70% of winter volume

Run

· 2 to 3 pairs of running shoes in rotation
· Track access for VO2 work
· Treadmill for intervals and winter
Cold country: treadmill essential November to March

Frequently asked questions

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