The Ironman marathon for most athletes involves a few hours of pure hell of just clinging on until the finish. Many of the field end up walking a significant portion of the marathon. There are common mistakes made by many triathletes when preparing for an Ironman marathon. These are the top 10!
1) Underestimate Training Involved
Quite simply, there is a ton of training to get done! Most Ironman athletes actually have full time jobs, families and many commitments on their time. Many triathletes underestimate what is required to complete an Ironman. They do not respect the distance. Many assume they are fit, they have already done a few 70.3s- how hard can it be?
The Ironman distance is a completely different race involving developing different energy pathways, different levels of training, different mind set, different nutritional strategies and different recovery strategies.
Progress does not come in a linear fashion. You must allow for training plateaus, injury and unexpected family/work events throwing you off course.
In our time crunched, goal oriented society, it is easy to simply throw an Ironman event on your goal list and before you know it, the event is 4 months away and you have not even got half way and require 6 weeks off running with shin splints!
Make sure you allow yourself enough time. You will require longer than you think. Respect the distance.
2) Lack of skill
Running is the sport that causes the most injuries amongst triathletes. Most triathletes have not got a lot of technical running skills. Perhaps we “got away with it” in shorter distances. But as you head towards marathon distance, any deficiency in technique will come back to bite you.
To run strongly in Ironman marathon, your skill level, your biomechanics MUST be improved and optimized. The better your running technique, the further you will be able to run with a lower heart rate, the further you will be able to run without fatigue and the less often you will get injured.
Take the time to get someone to video you and watch it back. If possible have one-two sessions with a running coach to point out the 1-2 things to focus on the improve your technique. Get your running analyzed at least once a year. It makes SUCH a difference. Poor runners use a ton more energy than runners who make it look effortless. It is not just about “fitness”, it is about developing good technique. If you want an online running course to help you, this one is excellent.
3) Lack of strength
More strength will prevent injury and will make you fatigue resistant. It will give you greater capacity to jump off the 112 mile bike and still have something left to give. It will help your ability to run any inclines that the course throws at you or power through a head wind without collapsing in despair.
Strength is one of the most under rated elements in Ironman marathon racing. Many triathletes think “I don’t have time” to fit in strength training. Quite simply if you want to do Ironman, you must! Check out the #1 strength training mistake made by triathletes.
Aim to do 2 sessions a week of squats and lunges. It will only take 15-20 mins. Then when you are on your bike, do big-chain high resistance intervals. Or find a decent 1-mile hill and do 10 repeats a week. The stronger you are on the bike, the easier your Ironman marathon will be. Here are some more strength work ideas.
4) Over-fueling before the Ironman marathon
Too much food and too many fluids is one of the biggest reasons for failure in Ironman marathon. It is easy to have the feeling that you are getting fatigued on the bike, so you ingest more fuel. What happens is the blood is diverted away from the working muscles to the stomach. All sorts of problems appear on the run when you are jostling around the contents of your stomach. There is a limit on how much it can handle. It simply cannot tolerate more than 50-60g carbohydrate and 500-750ml fluid per hour.
I have seen many triathletes take on far more fuel than they would in training due to nerves and excitement. The golden rule must prevail “Never do anything on race day that you have not done in training”. In my book Winning at 70.3 How to Dominate The Middle Distance, I have a whole chapter on specific fuelling and how to work out what YOUR body requires.
It will teach you a protocol to practice every week using the exact levels of fuel and fluid so on race day you are NOT guessing. Instead you KNOW what you need and you do not over indulge. You can apply these principles to any distance.
Equally if you tend to suffer stomach cramps and stomach issues in racing, it is worth checking out my colleagues book The Ketogenic Diet for Athletes
If you have not come across this concept, Charlotte explains how to train your body to rely on fat to burn for energy rather than requiring excessive amounts of sugars. This method has transformed many athletes Ironman marathons as they can more easily access their body fat for fuel and require far less sugary drinks and gels. It is not promoting a “no carb” diet rather just accessing more fat for fuel. If we can reduce the amount we ingest during a race, we will decrease the risk of DNF through stomach cramps and increase the amount of blood flow available to working muscles.
5) Neglecting Brick Sessions
A very specific skill for triathletes to guarantee success in Ironman marathon is mastering the transition. It is incredibly difficult to just off the bike after 112 miles and start running hard.
Brick sessions must be practiced at least 3 times a week AT LEAST. Make a point of every time you jump off the bike (even if it is on your turbo) plan to run for at least a mile. On weekends when you have a little more time, run 2-4 miles straight off the bike.
Start with a gentle run if this is new for you but as soon as you can make these race pace runs and start extending the distance.
Remember the golden rule- Never do anything on race day you have not done in practice.
6) Lack of pacing
Plan several race paced efforts well in advance of the race and know exactly what pace you will race at. Then plan a couple of mock races with your buddies or book a couple of shorter races to practice discipline of pacing.
What if the group lifts their speed on the bike leg faster than you had planned? Do you go with them or hold yourself back? Know your strategy in advance and stick to it.
There is no point gaining 2-3 minutes on the bike and then running out of energy in the Ironman marathon only to finish 33 minutes slower overall.
7 ) Lack Of Specific Ironman Marathon Training
You will need to be very intentional about the type of training you do. Preparing for Ironman is not simply doubling your 70.3 training or just having a vague idea of “doing more”. To be successful at Ironman marathon you need the ability to keep going for long period of time. In order to have enough left for the run, you need to be super strong on the bike. Nothing can substitute for time spent on the bike and volume of miles in the legs. Even if you are a world class sub 2.10 marathoner, you will struggle on the run if you are wrecked after the bike leg.
Any amount of hard turbo intervals will not substitute for doing several 100 mile rides before your event. NOT the week before!
Remember to save enough time of a good taper.
Yes I am a fan of hard, short brutal interval training for time efficiency and getting quick results (these WILL get you fit) but you still need to have done 4-6 bike rides of over 100 miles before your event to be confident you have enough to get through the ride plus some buffer left for the run.
8) Ignoring The Taper
Triathletes are intense beasts and are fairly disciplined on the whole. But one of the hardest skills to learn is to lighten up prior to the event. To do less. Our body gets stronger during periods of rest and we need to allow sufficient recovery time to allow our fuel systems to recover, our muscles, joints and even our minds to arrive on the start line feeling fresh. Most triathletes ignore their taper and keep training too close to the event.
They feel they are losing their edge. They imagine all the other competitor still out training and getting better than them. The discipline to taper is essential. Over 60% of competitors at a standard marathon arrive with tired legs and are not fully recovered in their glycogen reserves. They still have little micro tears in their muscles and are mentally exhausted. For Ironman racing, start your taper 3 weeks out. This does not mean finish training completely. It means gradually reducing your volume. It means keeping some intensity up to keep you sharp, but gradually easing up the volume and increasing your rest days.
There are plenty of stories of athletes forced to taper for several weeks prior to an event due to injury- who are stunned that they have the best race of their life. They realise it is the first time in their career they have been forced to taper properly!
9) Neglecting Recovery
To be strong at Ironman marathon, there is a lot of training to get done! In order to complete the weekly miles effectively, you must minimise injury and you must be able to recover quickly.
All the pros place a huge emphasis on recovery techniques and spend a large portion of each day in “active recovery”. Pick two or three that resonate with you and DO them regularly.
Calf Compression Sleeves you can wear under your trousers at work or when watching TV in the evening.


Cold baths only take 3-5 minutes. Take the time to do some stretches or book a sports massage once a month in advance so you know it will get done.
If you need an extra rest day schedule it.
It is far better to do effective training when you are feeling fresh than a load of sub-standard training when you are not performing at your best.
10) Ignoring The Mental Game
The Ironman involves a ton of time training. Even though we can train with buddies, there is a lot of time training alone. In the race you are alone too. You must develop the ability to control your focus. Are you focused on the finish line? Are you focused on the searing pain developing in your left calf? Are you focused on the head wind ruining your average speed?
Controlling your mental focus is crucial all the way through the training process, dealing with unexpected events, dealing with injuries, dealing with DNFs, dealing with disappointment, dealing with goal setting. Can you rig the game to win?
If you have a weak mind set, or allow your nerves or your lack of focus to distract you in the moment, it could ruin everything. Many of the pros have a daily mind set practice to strengthen their mind and control the story in their head. Anyone who does this regularly says they wish they started this sooner. All the greatest athletes in the world have a mind coach because it is that important.
Read what I think about when I run.
Start to apply a few of the technique to your training. Use “dead” time in traffic or in a queue to practice some of these techniques. For more guided on sharpening your mind strength and power, listen to this awesome audio book on Peak Performance next time you are on your indoor bike trainer.


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These are some very common mistakes made by triathletes when preparing for Ironman.
Even though people say triathlons are always won by the strongest runner, by the time you get to Ironman distance, there are so many factors involved that I believe the Ironman is won by the person best prepared and best able to attack their weaknesses.
It is a fascinating sport, all-encompassing and one thing it never is is boring.
Great article. Good reminder.