Ironman success: the 3 crucial elements to improve

Joe Friel identifies the three crucial elements for better long-course performance


Physiologically, there are only three things you can do to become fitter for triathlon: increase your aerobic capacity, elevate your lactate threshold and improve your economy. That’s it. Nothing else. All of your training comes down to these. But they aren’t of equal importance and you don’t need to focus your training on all of them. So which is the most important when you race long course?



You probably know this as VO2max. It’s a measure of how much oxygen your body processes when working at a maximal, aerobic rate. Physiologists define it as the maximal volume of oxygen consumed in millilitres per kilogramme of body weight per minute (mL O2/kg/minute). The higher your VO2max number, the more likely you are to perform at a high level in endurance events.

Your aerobic capacity is unique to each sport. If you have a high VO2max for swimming, it won’t necessarily be high for cycling and running. To improve your VO2max, do highly intense intervals in each sport. This workout would be something along the lines of three-minute intervals at an intensity you could hold for only about five or six minutes. Do four to six of these intervals in a session, with three minutes of recovery between them, at least once each week. If you were a single-sport athlete, such as a runner, I’d suggest doing three of these sessions each week. But as a multisport athlete, that’s obviously not wise. One such workout per sport per week is much better. This is best done in the last 12 weeks before your A-priority race.

Aerobic capacity is also raised by losing excess body weight. As the formula states, oxygen consumed is divided by body weight so, as body weight goes down, VO2max rises. At those rare times when your body weight has increased, riding your bike up a hill and running became a bit harder. In short, your aerobic capacity has decreased.

A high VO2max, however, is not critical to performance in a long-course tri. Why? Because at that race duration you’re not going to come close to your capacity for using oxygen. The race is long so you’re going slowly. However, the shorter the race, the more important VO2max becomes. For tri, aerobic capacity is an important determiner of performance and race results at the Olympic-distance and less so at longer distances.


You may know this as ‘lactate threshold’. While sport scientists differentiate between these two thresholds, these differences are not important for the average triathlete. Essentially, this is the highest intensity you can maintain for about an hour. Another way of considering anaerobic threshold (AT) is that it’s the intensity at which you begin to ‘redline’. When you cross this threshold as you speed up, you sense the effort just became hard. On a scale of 1 to 10 (with 10 being very hard), AT occurs at about 7.

In an Olympic-distance triathlon, a high AT is critical to performance. In the lab, it’s measured as a percentage of aerobic capacity. A highly fit triathlete will pass through the AT at around 85% of VO2max. Less fit triathletes will have lower ATs of between 75-80%. The higher the AT, the faster you can go for an hour or so.

If you’d rather not spend the money on a lab test to determine your ATs (it varies by sport), you can do a simple field test to find yours. For running and biking, I have athletes do a 30min time trial as if it were a race. For the swim they do a 1,000m time trial. The average pace (running and swimming), power (bike) or heart rate (all three) is approximately your AT.

To improve AT, do longer intervals at your AT pace, power or heart rate with short recoveries between them. For example, a common AT workout my athletes follow is 5min intervals done five times at their AT (5 x 5mins @ AT). The recovery between intervals is about a quarter of the duration of the hard effort. So, for 5min intervals, the recoveries would be 75secs. These sets could translate as a 300m swim interval, a 2-mile bike interval or a 1,200m run interval.

As your AT rises with increasing fitness, you will go faster at your AT heart rate or have a lower heart rate at your AT pace or power. You’re becoming fitter. When this occurs it’s time to retest your AT.


Sport scientists understand less about economy than aerobic capacity and anaerobic threshold. Yet it may be the most important of the three when it comes to endurance events.

I’m certain you understand the concept. Your car has an economy rating: how many miles it goes per gallon of petrol. Your body also has an economy rating: how far can it go on a given amount of energy (or oxygen which is an indirect indicator of energy use). While your car runs on petrol, the primary fuels for humans are fat and glycogen (stored carbohydrate). Highly economical athletes use their stored energy sparingly, and their bodies preferentially use fat for fuel while conserving glycogen.

There are many things that affect economy. Some of these are simply the result of genetics. For example, good swimmers tend to have long arms and big hands. Most of the best cyclists have long femur (thigh) bones relative to the lengths of their legs, while economical runners tend to have long tibias (shin bones). In general, the best endurance athletes have more slow-twitch muscles than power-sport athletes who’ve inherited lots of fast-twitch. The list of such genetic traits common to the best endurance athletes by sport is rather extensive.

The equipment you use also affects economy on race day. The most obvious is the use of aerobars on your bike. But others include ‘fast’ swimsuits, cleat placement on your cycling shoes, lightweight running shoes and many more. Becoming somewhat stronger and more powerful has also been demonstrated by research studies to improve endurance economy. That’s the reason many elite triathletes lift weights.

What’s often overlooked by triathletes in the area of economy is efficient movement patterns; in other words, skills. Triathletes generally work on their skills in swimming but give it little attention in biking and running. Yet economy may be improved by refining your technique. And this is perhaps the single most important thing that a long-course triathlete can do to improve economy and, therefore, race times. The more efficiently you move, the faster you go and the less energy you have to replace.

Ironman training: how to improve your efficiency in all three disciplines


Below is the data from one of my long-course clients showing how intensity relates to calories burned. The figures emanated from a recent bike VO2max test. Note how fat provides a higher percentage of calories burned at the lower-intensity Ironman pace compared to racing Olympic-distance. That’s why training your body to utilise fat when going long plays such a key role in race success.


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