12-Week Half Ironman Triathlon Training Plan

Swimmers in the 2015 Woburn Abbey Half Ironman
Swimmers in the 2015 Woburn Abbey Half Ironman (Image credit: tri for life)

Once you’ve thrashed out a few Olympic-distance triathlons and decided that it’s time to make the leap to a half Ironman, this training plan from endurance coach Steve Whittle will help you to do just that. 

“If you’re comfortable with the Olympic distance, this 12-week plan will allow you to progress to the half Ironman,” says Whittle. If you haven’t completed an Olympic tri, sign up for that distance first and use Whittle’s Olympic triathlon training plan to guide you.

We've also got some triathlon training tips from tri coaches, below the training plan.

How long is a half Ironman triathlon?

A half Ironman consists of a 1.2-mile/1.9km swim, 56-mile/90km cycle and a 13.1-mile/21.1km run. It typically takes somewhere between five and eight hours for amateurs to complete a half Ironman, though this will vary significantly based on the course and conditions. It’s a significant step up from an Olympic triathlon, which typically takes amateurs around three hours to complete.

12-Week Half Ironman Triathlon Training Plan

The plan below has been specifically designed to help intermediate-level triathletes prepare for the 1.9km swim, 85km ride and 21.1km run of the Woburn Abbey Half-Iron, presented by tri for life.

The plan keeps things simple and uses duration for each session. This ensures the body gets used to working for sustained periods and you don’t need to worry about covering specific distances. It also makes it easier to schedule all the hours of training in around other commitments.

Week 1

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MondayRest
TuesdayBike 60min
WednesdaySwim 45min and run 30min
ThursdayBike 90min
FridaySwim 30min and run 30min
SaturdayBike 90min
SundayRun 50min (with hills)

Week 2

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MondayRest
TuesdayBike 60min
WednesdaySwim 45min and run 35min
ThursdayBike 1hr 45min
FridaySwim 45min and run 35min
SaturdayBike 2hr
SundayRun 60min (with hill sprints)

Week 3

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MondayRest
TuesdayBike 1hr 15min
WednesdaySwim 45min and run 35min
ThursdayBike 1hr 45min
FridaySwim 45min and run 40min
SaturdayBike 2hr
SundaySwim 30min and run 65min (with hill sprints)

Week 4

Swipe to scroll horizontally
MondayRest
TuesdayBike 1hr 15min
WednesdaySwim 45min and run 35min
ThursdayBike 1hr 15min
FridaySwim 45min and run 45min
SaturdayBike 2hr 15min
SundaySwim 30min and run 70min

Week 5

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MondayRest
TuesdayBike 60min
WednesdaySwim 45min and run 30min
ThursdayBike 90min
FridayBike 30min and swim 45min
SaturdayRun 40min and bike 2hr
SundaySwim 30min and run 1hr 5min

Week 6

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MondayRest
TuesdayBike 90min
WednesdaySwim 50min and run 50min
ThursdayBike 2hr
FridaySwim 50min and run 45min
SaturdayBike 3hr
SundaySwim 30min and run 1hr 25min

running

(Image credit: unknown)

Week 7

Swipe to scroll horizontally
MondayRest
TuesdayBike 60min
WednesdaySwim 50min and run 40min
ThursdayBike 90min
FridaySwim 50min and run 35min
SaturdayBike 2hr 30min
SundaySwim 40min and run 1hr 25min

Week 8

Swipe to scroll horizontally
MondayRest
TuesdayBike 90min
WednesdaySwim 50min and run 50min
ThursdayBike 2hr
FridaySwim 50min and run 50min
SaturdayBike 3hr
SundaySwim 40min and run 90min

Week 9

Swipe to scroll horizontally
MondayRest
TuesdayBike 60min
WednesdaySwim 55min and run 45min
ThursdayBike 90min
FridaySwim 55min and run 40min
SaturdayBike 2hr 30min
SundaySwim 30min and run 1hr 35min

Week 10

Swipe to scroll horizontally
MondayRest
TuesdayBike 90min
WednesdaySwim 60min and run 55min
ThursdayBike 2hr
FridaySwim 60min and run 50min
SaturdayBike 3hr 15min
SundaySwim 40min and run 1hr 45min

Week 11

Swipe to scroll horizontally
MondayRest
TuesdayBike 1hr 15min
WednesdaySwim 60min and run 40min
ThursdayBike 90min
FridaySwim 60min and run 40min
SaturdayBike 2hr 30min
SundaySwim 30min and run 1hr 10min

Week 12

Swipe to scroll horizontally
MondayRest
TuesdayBike 90min
WednesdaySwim 40min and run 30min
ThursdayRest
FridaySwim 10min and bike 30min
SaturdayRace Day

Triathlon Training Tips

Fuel Your Engine

Aim to eat a meal containing a mix of complex and simple carbohydrates, plus some lean protein and healthy fats, two to three hours before your session. Scrambled eggs on wholemeal toast with some fresh fruit is a good example—it’s light and easy to digest and it’ll provide you with a sustained energy boost.

Improve Your Swimming Technique

If you are more efficient in the water, you’ll save energy for the rest of your half Ironman while still speeding through your swim. “Find a group to train with, or get a few private coaching lessons,” says triathlon coach Ian Rooke, who contributed to our guide on how to train for a triathlon. A dedicated tri coach is a better bet because tri swimming technique uses less kicking than traditional front crawl, conserving energy for the road.

Practice Swimming In A Wetsuit

“While wetsuits are great at providing extra warmth and hydrodynamics, they can feel tight and restricting at first,” says Phil Paterson of coaching company RG Active. “It’s important to work with the buoyancy of the wetsuit. The suit’s buoyancy should make everyone quicker, since you sit higher in the water and your legs don’t sink as much.”

Don’t Just Train Indoors

This goes for all three disciplines in the half Ironman. While smashing out sessions in the gym is convenient and great for your fitness, the best prep for your event will be outdoors.

“You need to learn how to tackle wind and rain, particularly on the bike where you’ll be required to brake and corner,” says Paterson. “Another key area not being used when training indoors are the stabilizing muscles in your hips and core, which are essential for efficient running and pedaling. Not only can weaker stabilizing muscles slow you down through inefficiency, they can also lead to a greater risk of injury.”

Ben Ince

Between 2010 and 2016, Ben was the deputy editor of Men’s Fitness UK, which predated, and then shared a website with, Coach. Ben also contributed exclusive features to Coach on topics such as football drills, triathlon training plans and healthy eating.