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As the triathlon season approaches there should be a shift in the training protocols and specificity of training and training intensities. This shift often forms the foundation of racing well and specificity forms an integral part of any program. The intensity at which you train can directly affect your performance outcome come race day – it is important to get it right! Read on to find out how and why…

What is intensity?

Firstly, let’s define intensity. Intensity can be described simply as: how hard your body works when training and racing. Science has allowed us to determine a number of important intensity defining benchmarks, which in turn have led to the development of numerous scales and measurements to help us define how hard we are working, as well as, how hard we should be working (depending on training goals).

Intensity is very individualised – it is important to note that one persons E3 may only be E2a for someone else. Intensity levels are dependent on a number of physiological parameters including age and training history.

Intensity Definitions

Here are some common terms that are used to describe intensity. Many require a lab test for an accurate measure, but predictions based on age, ability and feeling can still apply.

Lactate Threshold – also known as anaerobic threshold, this is the point where aerobic metabolism (energy supply) no longer supplies the majority of energy. It is signalled by a significant increase in Lactic Acid accumulation.

VO2max – or aerobic capacity is your body’s ability to uptake and use oxygen when working at max. It is determined by a VO2max test in a laboratory and is measured in ml/kg/min. VO2max can increase with training but is ultimately capped by genetics.

Max Heart Rate (MHR)– as the name suggests Max heart rate is your peak heart rate at maximal exertion measured in beats per minute (bpm).

MHR can also be determined during a VO2max test but also predicted using Miller, Londeree and Moeshberger method found here: (this new formula takes into account age, training age and sport).

Exertion– simply means how hard you are working

Race Pace– the pace and intensity that you are expected to race at

Why is it important?

The ultimate goal of training should be to increase your performance come race day. It is important then, that you reach race day in the best physical condition. This includes being adequately prepared, as well as ensuring you are not over trained. Furthermore, you need to know that that your body is prepared for what you are about to put it through come race day. Effectively managing intensity levels in training will directly affect all of the above factors. You should have an effective measure of YOUR training intensity. This will allow you to hit training targets but also ensures that your recovery sessions / intervals are completed and the correct intensity. When approaching race day these intensities come more and more important as you aim to prepare specifically for race day. Consequently, training should include sessions at race pace and approaching race distance. Furthermore, easy or recovery sessions should be just that!

Different training intensities and training zones will target different components of fitness. Lower intensity training target aerobic fitness and higher intensity sessions target lactate tolerance and anaerobic power. For more information please contact an ETPA coach.

How to Measure Intensity

There are numerous ways to measure intensity. Some use scientific measures; some are based purely on perception and some use actual data values. All can be very informative if used correctly and all can be extremely valuable. A summary of some common measures follows:

Perceived Exertions – As the name suggests perceived exertions are your individual perceptions on the intensity of a particular session or effort. We all use perceived exertion whether they are consciously aware of it or not. Such measurements of intensity are quick, easy, simple and individual but can be problematic when emotions are attached to these perceptions. It is important to ensure you are being honest with yourself.

Descriptive – sometimes perceived exertion can be as simple as easy, moderate, hard or on a scale of 1-10. Such measures are simple and easy to use and are fine for basic goals.

Borg’s RPE scale – was established and created by an exercise physiologist: Borg. This scale is slightly more comprehensive and specific and ranges from 6 (bed rest) to 20 (MAX) and is used by coaches and exercise scientists to gauge effort. The scale was chosen because the range corresponds roughly to a moderately fit, middle aged person and each number represents 10 percent of a typical heart rate, i.e. 60bpm – 200bpm.

Heart Rate – Heart Rate telemetry uses actual heart rate data collect by a heart rate monitor. The advantage of using heart rate is that it uses actual data and physiological information – the numbers don’t lie. This tool you can use to ‘listen to your body’ and can also be useful in teaching your body to do what you want it to do.

Percentage – maximum heart rate can be determined in a VO2max test or a simple 6min run test. Once this value has been identified it is simple to work out percentages and a fool proof tool to use on race day and compare to training heart rates. Furthermore, if you’re heart rate is higher or lower during a given training session compared to previous weeks this may be a sign of illness or overtraining… Using this method can help identify potential problems early.

Zones – whilst a VO2 test is again the most accurate way to determine your heart rate training zones they can be calculated using your MHR. Zones range from recovery to E4 and provide a HR range for training sessions which ensure you’re at the correct heart rate for peak performance. Different zones would be used for different training goals – see table 1 below.

Power – A relatively new but very useful training tool, power metres allow you to test and use wattage in training. And then transfer this data and use it on race day. Once set up, power metres are easy to use and a direct, real time measure of your power output on the bike. Use of this tool ensures that your easy rides are easy, allows comparison between sessions, or previous bests, means you can determine a safe wattage for race day in training, and/or, train at a desired power output. For example, from previous Journey articles we know many professional Ironmen ride at 280W over the 180km. The use of power in training and preparing for your race day power output means you can ride safely throughout the bike leg knowing you are safe at that wattage regardless of hills, wind or road surface.

Pace– Whilst traditionally an older training tool to determine your training intensity, advancements in technology and greater use of GPS enabled training tools mean using pace is easier than ever. Pace is still the best indicator for swimming intensity with use of the pace clock, for example 100s on a 120 cycle. Coupled with race times it is often easy to determine ‘race pace’ and desired race pace. But, using pace in running used to require a measured distance such as a track and breaking running intervals into 400m or 1km efforts trying to hold a certain time cycle. However, accelerometers (often used by AFL clubs) and GPS units such as those designed by Garmin can now provide direct feedback as to your running speed.

HR vs. RPE vs. Description – understanding intensity

Below is a table which matches a number of common measures of intensity up against one another. Pace and / or power output could be added to the table if the data was available for any given athlete. For example, if you might know that riding at 200W requires an rpe15 effort, or running at 3.20pace means you are working at E3+.

Table 1– Comparing measures of intensity

Exertion Borg’s RPE HR % HR Zone


Very, Very light 7 30


Very light 9 40 Recovery

10 Recovery

Moderate 11 50 Recovery

12 Recovery

Somewhat Hard 13 60 E1

14 E1

Hard 15 70 E2a

16 E2a-E2a+

Very Hard 17 80 E2b

18 E2b-E2b+

Very, Very Hard 19 90 E3 – E3+

20 E4

MAX 100 E5

Applying intensity to your training…

As stated at the top of the article, the aim of any training program should be to improve performance. Training intensities should, in turn, be determined by the goals of individual sessions, race distance, fitness levels and goals of the overall program. Recovery sessions, easy sessions, rest intervals and the like should be completed at recovery heart rates, low RPE, low wattage. Similarly, a couple of sessions each week should be completed at race intensity, to allow you to teach your body to cope and react at this level and ensure adequate preparation for what happens on race day. Sessions at threshold or above/an intensity/pace/wattage/HR higher than that expected on race day are also required to ensure improvements in fitness, strength and speed. If used correctly, measuring intensity of training can also help reduce the risk of overtraining, ensure adequate preparation for race day and identify overtraining. For example, if you are running at an easy pace but your heart rate is at 75% of MHR this might be an indicator of overtraining.

It is important to note that no single measure of intensity is superior to others. For most effective intensity management it is suggested that you use two or more measures in unison. Furthermore, intensity is extremely subjective – no two athletes are the same and hence intensities vary greatly from athlete to athlete.

The information used in this article is gathered from the authors experience as an athlete, coach and exercise scientist and has been compiled as a guide only. For more information on the content and any of the concepts discussed please contact an ETPA coach directly.


Joe Friel, Triathlete’s Training Bible, 3rd edition

BrainMac – maximum heart rate

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