Can I Do An IRONMAN On Six Months Of Training?


A long distance triathlon (such as IRONMAN), is one of the biggest physical challenges in sport. But how long will it take you to train for one?

How long does it take to train for an IRONMAN 140.6? We’re talking a triathlon consisting of a 2.4-mile swim (3.8km), 112-mile bike (180km) and 26.2-mile run (42.2km).

With all the other triathlon distances, you can just about get away with under-doing your preparation and still make it to the finish line. But not with a full IRONMAN. If you fail to respect it, it’ll find you out.  

Finishing it well within the 17-hour cut-off comes down to numerous factors, the most important being your current fitness.  As a rough idea, you’re looking at six to 12 months of training, depending on your background. 


In times gone by, it was thought you’d need two to five years of triathlon racing behind you to even consider taking on the behemoth that is an IRONMAN.

That meant graduating from sprint distance (750m swim, 20km bike, 5km run) to Olympic distance (1.5km swim, 40km bike, 10km run) and then up to middle distance, with its 1.2 mile (1.9km) swim, 56-mile (90km) bike, and 13.1 mile (21.1km) run. Finally, you were ready for the big one.

Not anymore. Now, with refined training practices and cutting-edge training tools, things are different. Some people battle through an IRONMAN 140.6 with fewer than a handful of triathlons behind them. Unbelievably, some make their first triathlon an IRONMAN 140.6! Then again, this is multisport, rather than single-sport. Many athletes who participate in triathlon have already forged a powerful engine, be it in swimming, cycling, running, or other endurance disciplines.

As a general rule, if you’re reading this on the day you’ve completed your first IRONMAN 70.3 (half the distance of a full IRONMAN), I’d confidently say that with consistent training, you could complete a full-distance in six months, maybe less. 

Another way of looking at it is if you can complete a half-distance in eight hours or under – without feeling like you can’t walk for the next month – you’re on course to finishing a long-course triathlon in under the 17-hour cut-off. 

If you’re new to triathlon training but have a reasonable background fitness, I’d say 12 months is a more realistic yardstick.

That doesn’t marry with many training plans floating around the internet, telling you to go from zero to IRONMAN hero in 12 weeks, but that’s a risky throw of the dice. 

Your body must absorb a hefty volume of training while recovering between sessions, plus you must juggle work, family, and everything else. You should also be prepared to ease off on the social functions so you can take IRONMAN training seriously. 


So, first things first, due to the long distances involved, you’ll need a dedicated training plan. 

That might sound serious, and it’s certainly a mindset shift from potentially less formalized training at lower distances, but the structure is essential to reaching your goals. Being an amateur, one of the greatest obstacles to overcome is time.

I always say that training for an IRONMAN is broadly similar to training for shorter triathlons, but the biggest difference comes at weekends when you’ll have longer workouts to tackle. Of course, you don’t HAVE to do your longest workouts at the weekend, but that’s typically when most people have the opportunity.  

So, ask yourself a few questions: do you have enough time to tick off regular 4-hour bike rides at weekends? Rides that could grow to 5- or 6-hours? And how does that gel with your family or work responsibilities? Remember, you’ll be very tired afterwards too. 

The swim training is not quite as demanding, although you’ll need to build up to 2.4 miles (3.8km) of comfortable swimming, in the pool or open water. That can typically mean workouts of 90 minutes or more. 

Running is a discipline that requires careful attention. It’s high-impact, and injuries are more likely to derail you. Some of your long runs will gradually build up to 2 hours 30 minutes in duration to prepare you for the marathon effort on race day. Some people run for even longer in training, but doing so increases fatigue and injury risk.

All in all, to train for a long-course triathlon, you’re looking at around 1-2 hours a day, for five or six days a week. With longer workouts typically at weekends.  

If that time requirement has not put you off, here are 3 top tips for time-efficient IRONMAN training… 


To be successful, you need to be consistent. If you can complete 85% of your training plan 85% of the time, that (or anything greater) ranks as consistent. To do this, you must be realistic about your time availability in the first place. 

Consistency also means avoiding injury, which you can do by not dramatically increasing your training hours or going too fast during long workouts. Taking an active recovery week every few weeks helps, too. 


Fueling is vital at long distances, especially on the bike, and you should consider most long training rides your meals-on-wheels service. Many watches now have the capacity to remind you to eat every 15-20 minutes, even if it’s just a simple count-down timer. 

As for what you should consume during an IRONMAN 140.6, that’s a separate blog, which you can read here. 

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This is an essential component of your structured training. You should write down your goals and sessions and chart your mood and impact on performance. This is useful to avoid overtraining. 

Software like TrainingPeaks is ideal for this, which is why I use it to create flexible training plans. But no matter how you chart your training, keep a post-it note reminder about your goal on your fridge. It’ll motivate you whenever you reach for a beer or an unhealthy snack.

In conclusion, training for an IRONMAN is not easy. It demands a lot, not only from you but also from your friends and family. So get them on board early to make your journey that bit more enjoyable. 

And never forget that aspect – this is supposed to be enjoyable. Remember to smile, take pride in your training and be consistent. 

Be realistic about your goals, and don’t expect miracles. And before long, you’ll have that long-course medal slung around your shoulders. And then what? Of course, you’ll sign up for IRONMAN number two…

Phil Mosley (Coach & Founder)
Phil Mosley (Coach & Founder)

Phil is a recognised endurance expert who founded MyProCoach in 2010 to offer smart training plans that still leave quality time for your family, friends & career - complete with highly-rated coach support (he has sold over 40,000 so far). Learn more here!

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