How to race your first Ironman

Fitness wise, you’re ready to go and race your Ironman, but don’t think that all that’s left to do is compete. Mark Kleanthous explains the tactics needed to race Ironman


Once optimum fitness has been reached, many athletes make the mistake of forgetting two fundamental strategies for race-day success – nutrition and pacing. Without addressing these two areas, there’s a strong chance that you won’t make the finish line. Here I’ve outlined the key areas within an Ironman and what you should be doing to pace both yourself and your nutrition intake in each.



The day before the race is crucial – you shouldn’t be doing much of anything. Practise your race morning breakfast; the more times you practise this, the more confident you will be and will have no doubt as to what works for you. Don’t forget it can take up to 45 minutes to digest your foods race morning due to nerves.

Aim to eat your final large meal early in the day (I always eat my main meal before 4pm and then just snack for the rest of the day) because this gives your digestive system time to work.

On the morning of the race itself, never rush putting on your wetsuit. You can get away with creases in a sprint but not in an Ironman. Also, avoid the temptation to tighten the neck more.

Warm up gently, by spending three to five minutes doing arm circles.


The first six minutes are very important – don’t go off too hard. Going out too fast in the swim can ruin not just the swim but also the whole Ironman. Most of the starters will slow down, so go off steady. This is paramount in a 3.8km swim because it’ll reduce the number of metres you swim and save energy for the bike and run. If you swim 100m in 1:40mins, each time you go off course just 1m, you can lose 3secs by not swimming in a straight line.


Only drink water after the swim and avoid eating a sports bar or sports drink. You need to let your muscles settle down during the bike first.

The last place you should be running is in the transition area. If this is your first Ironman, there’s absolutely nothing to be gained by it. It will drive your heart rate up and cause you to make mistakes.


You’ll find your cycling legs much quicker by avoiding drinking for the first five to 10 minutes of the bike.

If you start to feel low in energy, never think consuming a whole bar in one go will help. Little and often while easing back is your miracle cure until you have enough energy to start increasing the effort.

Save your strength for as long as you can. You don’t need a cadence monitor or power meter to tell you this. Feel the
gear – if you’re pushing then you’re almost certainly in too big a gear. Spin at a nice relaxed pace for the first 40km or so and then pick it up a little to the pace you feel you can maintain for the bulk of the ride.

If you take 10 minutes more in the second half of the bike than in the first, you’ve almost certainly gone out too hard and will have a disappointing run and slower overall time.


Don’t drink any coke, otherwise you’ll be flying for the first 10km of the run and ruin your pacing. Instead, drink up to 150ml
of whatever you drank on the bike to revive your taste buds, and avoid solids until you find a running rhythm. Allow at least a 10-minute break between gels and coke to avoid being sick, as some of a recently ingested gel may still be in your stomach.

Don’t rush dismounting as you can easily cramp a fatigued thigh or hamstring. Do the Ironman shuffle out of T2 to avoid muscles tightening and cramping – your legs will tell you when they’re ready to run.


Have a well-conceived run nutrition plan that you’ve tried in training.

How to (and how not to) do an Ironman

Below are two age-groupers who finished the same Ironman within only 13secs of each other. However, their splits were very different.

Triathlete A

Swim = 1:03:06

Bike = 5:21:02 (average speed 33.6km/hr)

Run = 6:24:52 (1,049th)

Total = 12:57:44 (680th)

Triathlete B

Swim = 1:15:41

Bike = 6:56:41

Run = 4:33:48 (501st)

Total = 12:57:57 (682nd)

Triathlete A spent 8.1% swimming, 41.3% cycling, 49.5% running, and 1.1% in T1 and T2.

Triathlete B spent 9.7% swimming, 53.6% cycling, 35.2% running, and 1.5% in T1 and T2.

Triathlete A went out far too hard in their best two disciplines, the swim and bike, feeling that they could hang on during the run. This plan went disastrously wrong, resulting in a longer run split than the bike.

Triathlete B had a great Ironman with even pacing in each discipline and performed to the best of their ability, making no mistakes on race day. The run split is not evidence of being a better runner or even having better endurance, but does show good nutrition on the bike.


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