Expert Michael Ricci explains why pacing is essential when racing long-distance triathlon

A question I’m frequently asked is, “What is the ideal heart rate for an Ironman?” Whether you’re looking to win or just finish, this is an important question. As you head into the off-season with visions of Ironman success, it’s a good time to think about how you train in terms of your intensity. As a coach, I frequently hear of athletes who have a great bike ride at an Ironman, followed by a run that was less than optimal.

There is no such thing as a great bike ride, if you then have a lousy run. With most athletes, I go back and look at training intensity and have athletes back off on the longer workouts, and believe it or not, that usually does the trick.

While it sounds easy, many people struggle with backing off. The winter is the perfect time to look back and make corrections to your training. If you want to make a difference in your next endurance event, you need to start now.

Many athletes assume they can happily race an Ironman in zones two and three (see Your Training Zones) but believe me, that would be tough – even for an elite athlete.

The Endurance Zone

Before you get to race day, your Ironman training should mostly have been done in zone two. This is sometimes known as the endurance zone – a heart rate that can be sustained over a very long period of time. This is because in this zone the body will utilise the biggest resource we have for fuel: fat. We have a vast supply of fat stores that if trained properly would allow us to run back-to-back marathons.

When we cross over into zone three, we tap into more of our glycogen stores, and the body can only operate using stored glycogen for two to three hours, tops. These zone three efforts should be reserved for the final miles of a half Ironman or marathon, and only for a well-conditioned athlete.

Going into zone three in an Ironman – for an athlete who is racing longer than 11 hours – would be setting you up for a tough run. You’re better off moving along nicely in zone two, rather than depleting your stored glycogen in zone three and then slowing right down. Initially, zone two may seem too easy, but stick with it and over time you’ll see an improved pace at the same heart rate.

Cardiac drift

Another consideration is cardiac drift, a condition that is likely to occur when you are getting back to normal training levels or taking on a new training regime. This is where your heart rate rises into zone three although your effort remains in the zone two range – a perfectly normal occurrence, but one that should be avoided as much as possible even if it means walking in order to keep your heart rate down.

I do allow my athletes to experience this once per week when they are starting up training but I make sure that they know to back right down and stay within the set parameters indicated in their training plan.

Once you have a solid endurance base, you shouldn’t see much in the way of cardiac drift unless you are dehydrated. If you are training or racing in the heat, you may need to let your heart rate drift and instead measure your effort by RPE (Rate of Perceived Exertion). But only do so if you have taken into account the extra calories your body will use trying to keep cool.

Imaginary Joe – an example

To put all of this into perspective, let’s take a look at an imaginary Ironman athlete, Joe. When training in zone one to two Joe should be running “easy”. I like to refer to this as the “guilty pace”. Let’s say for him that might be around 135 beats per minute, which would put him near the top of zone one.

When he’s running at a steady pace Joe’s heart rate is more like 140-145 beats per minute, and this puts him in the middle of his zone two. This would be about right for an Ironman effort. After 112 miles of cycling, if Joe can maintain his steady running heart rate for 26.2 miles he would, with all other factors being equal, be running the same pace as he had on his long training runs. And that would lead to a pretty solid Ironman marathon time.

What about cycling? Most athletes will see somewhere around an eight to 12 beat difference between their bike and run heart rates. For example, when Joe trains on his bike and is riding “easy” his heart rate is in zone one – around 125 beats per minute. And when he’s biking steadily he’s around 135-140 beats per minute (bpm), which puts him in the middle to the top of zone two. With the exception of climbing hills, he shouldn’t reach over 140bpm in training when the workout calls for a steady effort. There are times that he might see 145bpm on a steep hill, but that would otherwise be rare. During his Ironman he will still have to run 26.2 miles after this 112 miles of cycling, so he shouldn’t be hitting the accelerator on the bike if he wants to run well.

When writing an Ironman training plan, I’ll give an athlete a directive of, “This is a zone one to two workout”. The athlete is expected to find the medium and train at a pace they can sustain all day. When I review a log, I sometimes see entries saying that they bonked or faded in the later stages. This is often an indicator that the athlete is training too hard and that I need to do a better job of explaining what output I want to see from that athlete.

If you can follow the above recommendations, and practise the discipline of simply training steadily, you will, over time, improve your running and cycling efficiency. And this kind of improvement will pay big dividends on race day. is the online home of Triathlon Plus. Save time and money by having every issue delivered to your door or digital device by subscribing to the print edition or buying digitally through Zinio or Apple Newsstand.

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