How long is a typical Half Ironman training plan?

A well-structured Half Ironman plan typically runs 16–20 weeks, depending on your starting fitness level.

How many hours per week for Half Ironman training?

Most Half Ironman plans require 8–12 hours per week, scaling up through the build phase and tapering before race day.

Can AI build a personalized training plan?

Yes. An AI coach checks your recent training data, researches your specific race, and builds a periodized plan grounded in your actual fitness. Ask it why a workout is prescribed and it explains the reasoning. Flag an injury or schedule change and the plan adjusts through conversation.

Half Ironman Training Plan | Race Training Plan

What it takes

Half Ironman training is a volume game. You need enough bike endurance to ride 56 miles and still run a half marathon, enough swim fitness to exit the water fresh, and enough recovery discipline to absorb 8–12 hours of weekly training. The long brick workout — 3+ hours of bike followed by a run — is the signature session.

Training phases

Weeks	Phase	Focus	Volume
1–4	Base	Aerobic volume across all three sports, build long ride to 2 hours	Low–Moderate
5–8	Build I	Threshold work, introduce long bricks (2h bike + 30min run), swim to 2,000m+	Moderate
9–13	Build II	Race-specific intensity, long brick to 3+ hours, long run to 12–13 miles	Moderate–High
14–16	Peak	Highest volume, race-simulation brick (3.5h bike + 60min run), peak long ride	High
17–18	Taper	Volume reduced 40–60% over 2 weeks, short race-pace openers, full recovery	Low

Key workouts

Long brick: 2.5–3.5 hour bike → 45–60 minute run
Swim endurance: continuous 2,000–3,000m sets at race pace
Bike long ride: 3–4 hours with race-pace segments
Run long: building to 13+ miles at easy-to-moderate effort

Am I ready?

You should be training 6–8 hours per week across all three sports, with a long ride of 2+ hours and a long run of 8–10 miles. A completed Olympic triathlon or standalone half marathon provides the best foundation. The jump from Olympic to 70.3 is significant — your longest training days go from 2 hours to 4+ hours.

What to expect on race day

The half Ironman is a 4.5–7 hour race. The 1.2-mile swim is a warmup for what follows. The 56-mile bike is where pacing discipline matters most — ride 10 watts too hard and you'll walk the run. Nutrition on the bike is mandatory: aim for 60–80g of carbs per hour from sports drink, gels, or bars. The half marathon off the bike is nothing like a standalone half — your legs are pre-fatigued and your stomach has been processing fuel for 3+ hours. Walk the aid stations, pour water over your head, and keep fueling. Expect to run 10–20% slower than your standalone half marathon pace.

Common mistakes

Biking too hard — power or heart rate should be 70–75% of your FTP/max; the run is where the race happens
Insufficient bike nutrition — bonking on the run usually traces back to underfeeling on the bike
Not training long enough bricks — if your longest brick is 2 hours, a 5+ hour race will be a shock
Neglecting heat and hydration planning — many 70.3 races are in summer; train in heat if you'll race in it
Ramping volume too fast in the build phase — injury risk climbs sharply when weekly hours jump more than 10%; patience is the plan

Sample week

Week 12 of 18·Build Phase

7h 05m planned

Day	Session	Duration	Zone
Mon	SwimSwim — Endurance	50m	Z2
Tue	RunRun — Tempo	55m	Z3
Wed	BikeBike — Indoor Tempo	60m	Z3
Thu	SwimSwim — Threshold Set	45m	Z3
Fri	RunEasy Run	35m	Z1
Sat	BrickLong Brick — Bike → Run	180m	Z2
Sun	RestRest	—	—

How it works

The coach researches your race

Name your event and the coach searches the web for course profile, elevation, and conditions — then factors them into your half ironman plan.

Your plan starts where your fitness is

The coach checks your recent Strava activity and your local weather before recommending anything. A 16–20 weeks plan structured by phase — base, build, peak, taper — around what you can actually do.

Train, sync, adapt

Activities auto-match to planned sessions. The coach sees your paces, HR, and effort patterns — and adjusts as your fitness changes. Flag a bad week at work, a nagging knee, or a schedule change, and the plan adapts through conversation.

See it in action

I signed up for the Chicago Olympic Tri in August. I can swim and run fine but my bike is weak — I've only been riding for 3 months.

CoachSmart to flag that early. I'll weight your plan toward bike volume — three bike sessions per week vs two each for swim and run. We'll build your long ride from 60 min to 2+ hours by race month, with brick sessions every Saturday so you learn to run off the bike.

Should I do a sprint tri first as practice?

CoachAbsolutely — I'd slot one in around week 8. It's the best way to rehearse transitions, open-water swimming, and race-day logistics without the pressure of your A-race. I'll taper lightly that week and treat it as a training race.

Why AI coaching

Manages the high weekly volume without pushing into overtraining
Long brick sessions progressively built — not thrown in randomly
Balances three sports when one inevitably falls behind schedule
Volume progression follows evidence-based limits — no reckless jumps in training load
Tell the coach about a bad night of sleep, a schedule change, or a nagging injury — and the plan adjusts through conversation, not a settings page
Searches the web for your specific race — course details, elevation, and conditions inform the plan

Grounded in training science

Plan structure draws on Daniels’ Running Formula, Pfitzinger’s Advanced Marathoning, and Friel’s Triathlete’s Training Bible — periodized across swim, bike, and run with sport-specific taper timing. Intensity distribution follows the polarized model (Seiler 2010; Stöggl & Sperlich 2014) — roughly 80% of training at low intensity with targeted hard sessions, rather than moderate effort every day. Volume progression stays within evidence-based limits to manage injury risk (Nielsen et al. 2012). Taper protocols reflect findings from Wang et al. (2023), a meta-analysis of 14 studies on optimal taper duration and training load reduction for endurance events.

Seiler, S. (2010). “What is best practice for training intensity and duration distribution in endurance athletes?” Int J Sports Physiol Perform, 5(3). · Stöggl, T. & Sperlich, B. (2014). “Polarized training has greater impact on key endurance variables.” Front Physiol, 5. · Nielsen, R. et al. (2012). “A prospective study of overuse running injuries.” Br J Sports Med, 46(6). · Daniels, J. Daniels' Running Formula, 3rd ed. · Pfitzinger, P. & Douglas, S. Advanced Marathoning, 2nd ed. · Friel, J. The Triathlete's Training Bible, 5th ed. · Wang, Z. et al. (2023). “Effects of tapering on performance in endurance athletes: a systematic review and meta-analysis.” PLOS ONE, 18(5).

Frequently asked questions

How long is a typical Half Ironman training plan?: A well-structured Half Ironman plan typically runs 16–20 weeks, depending on your starting fitness level.
How many hours per week for Half Ironman training?: Most Half Ironman plans require 8–12 hours per week, scaling up through the build phase and tapering before race day.
Can AI build a personalized training plan?: Yes. An AI coach checks your recent training data, researches your specific race, and builds a periodized plan grounded in your actual fitness. Ask it why a workout is prescribed and it explains the reasoning. Flag an injury or schedule change and the plan adjusts through conversation — not a form field.

Half Ironman Training Plan