Training Intensity

The purpose of training, is to improve your fitness so that you can go the distance, or better still, go the distance faster. But what type of training to do is often the confusing part. There are many excellent books on the theory of training intensities for swimming, cycling, running specifically for triathletes, but we won't go into science here. Instead, this article is a plain English explanation of two popular ways of increasing your lactate threshold through either aerobic conditioning or High Intensity Interval Training (HIIT). Even if you don't like getting bogged down reading the theory, spare 5 minutes to read this information and you could radically change your approach to training and make some real gains in your next triathlon.

Base Fitness

If you are a newcomer to competitive endurance sport your main goal of training is to develop your aerobic capacity to last the distance - regardless of pace. This means you need to sustain the effort level over the duration.

For beginners, and for any of the triathlon disciplines, your training paces will be determined purely by your general fitness. In triathlon terms, this is your “base” fitness. Your base fitness can be radically improved through training. But deterimining what type of “training” is best to improve your base fitness is often the confusing part for beginner triathletes. And once you have mastered the distance, what's the best way to go about improving speed?

Let’s make it simple without trying to get too heavy into the sports science and theory. If you’re into that kind of thing, go into our online shop and choose from the many excellent books and dvds produced by the world's leading coaches and experts. If not, read on to gain some practical information to improve the quality of your training sessions.


The first thing to address in your life when about to embark on improving your base fitness is to test it before you seek to improve it. This doesn’t have to be complicated. But here’s a few ways to get some basic data.
  • Find out your resting Heart Rate
  • Next, calculate your Maximum Heart Rate using this commonly accepted formula HRmax = 220 – age
  • Next, you should look at doing some basic time trials to determine a benchmark of your swimming, cycling, and running fitness. See the Time Trial section below for guidelines
  • After doing each time trial immediately take note of your heart rate, then take it again after a 1 minute rest period. This helps determine a benchmark of your recovery heart rate. A greater reduction in heart rate after exercise during the reference period indicates a better-conditioned heart


See our article on Heart Rate Training Zones for more information and tips on this subject.

Time Trials

Time Trials are a simple and informative way to gauge the effectiveness of your training. Often performed at the beginning of a season, then again every 2 months or so, this should give you the best indication of how you are responding to the training.

For swimming, you should know your 100m and 300m pace so set these as your time trials, (depending on your swimming ability).

For cycling, you should know your 10km, 20km, and for experienced cyclist's, also your 40km pace, so set these are your time trials (if practical and within your capabilities).

For running, you should test your 400m, 800m, 5km and 10km pace so ideally you should TT these distances also. However, you would not attempt to time trial a distance that was not achievable for you, so just use common sense. 400m and 800m time trials are best done on a firm grassy oval or athletic track. 1 lap of a standard sports oval is usually 400m.

Time trials don’t have to be overly scientific, but there are a few basic rules. Never do your time without a decent warm up; only do 1 time trial per session; always choose a day and time that offers you favourable conditions and minimal interruptions; and always choose a course for your cycling and running time trials that you can reuse for future time trials.

Training Intensities

Now that you’ve got your benchmark testing, your goal is to undertake the right type of training to enable a change in your fitness and therefore a performance improvement to occur.

Can you complete the distance required for the race ahead? If not, you need to focus on increasing your endurance capacity. This means working at increasing distance without exhaustion.

Once you can do the distance, then aim to increase your speed. The key to racing, is to find the fastest pace that you can sustain for the given period. Sports science shows us that there is a limit to how long we can sustain certain exertion levels and that this is variable for each individual and based on fitness.

The point of exertion, when the body goes from being in an aerobic state to an anerobic state is called your Lactate Threshold (LT). The point at which this occurs is measured in terms of bpm. This point is often very different from swimming to cycling to running so you need to test and measure each discipline. If you train regularly with a HRM monitor you may get a gauge for the exact bpm at which this occurs for you in each sport. Otherwise, you can undertake a VO2max test (usually too expensive for the general person) in which your thresholds and other data will be measured.

The aim for all triathletes is to delay the onset of LT. For lazy athletes, this means going slow, and keeping the heart rate under control. But if you wish to be competitive however, this means undertaking a program that improves your system so that the bpm rate at which you reach LT is delayed.


To read more detailed information about training intensiites, you can read our article on Heart Rate Training Zones.

How to increase your Lactate Threshold

“Lactate threshold” is also known as your “aerobic capacity”, or even “anaerobic threshold”. Sorry for the jargon but this is important to understand. Whilst it is generally agreed that the best way to improve your “aerobic” capacity is to perform long duration training at very low intensity, this requires very long training sessions. In fact, most people simply don’t allocate enough time to perform sessions that are long enough to truly build their aerobic capacity by exercising at sub-threshold intensity throughout. Instead, many triathletes are happy to train frequently, often 2 sessions per day, but will often only have a maximum of 1 ½ - 2 hours to dedicate to each session. For these triathletes, sub-threshold training is not sufficient to trigger an effective response to see improvement gains.

Research over the last few years has proven that high intensity interval training (HIIT) is very effective at improving aerobic capacity. The big difference however is that it is much quicker to use HIIT methods to get the same results (which brings all sorts of other advantages), and furthermore, research and experience is also showing that athletes that use a program that combines both long/slow efforts and HIIT in the weekly schedule brings about the "best" results.

With most triathletes having to juggle busy lives, with work and family responsibilities, it is great to know that using HIIT training effectively means you can make great improvement gains without having to do more than 8-10 hours per week.

The Principle of HIIT Training

High intensity interval training is a specialized form of interval training that involves short intervals of maximum intensity exercise separated by longer intervals of low to moderate intensity exercise. It can be used effectively in all three disciplines of triathlon training – swimming, cycling, and running.

To get the benefits from HIIT, you need to push yourself past the upper end of your aerobic zone and allow your body to replenish your anaerobic energy system during the recovery intervals.

The key element of HIIT that makes it different from other forms of interval training is that the high intensity intervals involve maximum effort, not simply a higher heart rate.

The purpose of HIIT is to increase the amount of time you spend exercising at very high intensities.

Let’s take an example: your best 5K race time is 27:30 (5:30min/km). If you could improve your ability to hold a pace that was faster by 15 seconds per kilometre, you’d need to run at 5:15min/km pace, which would require a 25% increase of pace.

The HIIT approach is designed to work you at that higher intensity in short bursts, with short recovery periods to increase the effectiveness of your training. Improving the quality of your sessions means you need to be increasing the time spent above lactate threshold. Training at intensities above 90% VO2max is one of the most potent routes to fitness. Controlled interval sets allows you to enter your 'red-line' training zone productively.

But you must work as hard as you can during the high intensity intervals, until you feel the burning sensation in your muscles, and the I-am-going-to-vomit feeling in your chest, that indicates you have entered your "anaerobic" zone. Elite athletes can usually sustain maximum intensity exercise for three to five minutes before they have to slow down and recover, so don’t expect to work longer than that!

Full recovery takes about four minutes for everyone, but you can shorten the recovery intervals if your high intensity intervals are also shorter and don’t completely exhaust your anaerobic energy system. You may need to experiment with this a bit. Just keep in mind that if you are trying to improve your lactate threshold then try to keep recovery intervals short.

A simple and effective method to get started with HIIT is to match the recovery time to the effort time and then try to shorten the recovery. Every second counts, so use a stopwatch or better still HRM/computer to monitor every rep. If your need longer recovery than your effort times, you need to reduce your pace in the efforts a little. Alternatively, you could do less repetitions and work towards building up more reps over time.

High-intensity training can be tricky to manage. Follows these 3 tips to ensure your HIIT is beneficial:
  • Don’t make all workouts HIIT
  • Do plan your HIIT sessions deliberately. These do not need to be very long sessions, so are ideal for before work
  • HIIT also needs appropriate recovery. The next session the following day needs to be a recovery session such as a swim, endurance ride, or a rest day. Use common sense
  • Do everything you can to ensure good form so get a bike fit, use a coach, etc

Common Training Mistakes

Any training plan that suggests sticking entirely to one low intensity for an extended duration defies what we know about how the body responds best to the stimulus of training. Look out for these commons mistakes with your training intensity.

Going hard too often

The maximum number of speedwork sessions an athlete should perform in one week is three, and time spent above LT should be no more than 10% of your total weekly exercise time. This number has been proven both in research and in practice around the world by the top triathlon coaches. Athletes who try to do too much speedwork in a given week will either burnout or perform with sub-optimal intensity.

Not going hard enough or long-slow enough

According to the experts, it is common for most age-group triathletes to neither go hard enough to make speed improvements, nor easy enough to do the very long efforts to bring about any significant aerobic improvements. When this occurs, triathletes will find themselves at a plateau, where despite all their training, they feel they aren’t seeing any results or improvements. If this describes you, then consider that you are not pushing yourself hard enough in your interval sessions, or aren’t making those long-slow sessions long enough to create the necessary training stimulus.

Not going hard ever

Sometimes, endurance athletes forget the importance of speedwork. Low intensity and higher volume training actually places plenty of stress on the system. As stated by one of the leading experts in the field of sports science in the modern day, Chris Carmichael says “

"You win long triathlons with sub-threshold speed, but you gain the ability to be fast at a sub-threshold intensity by training with efforts at and well above threshold".

The Ideal Plan

Ideally, to train smart, you should enlist the help of a coach who will work with you on an individual basis. I've written a whole separate article about this, Triathlon Training Programs and Coaches. They will test you, they will write your program, they will tell you when to push to your max, when to go long-slow, and they will monitor your rest and recovery, and they'll support you all the way through to race day. Unfortunately the cost of a coach is too much for age-groupers like us to justify. But don't give up - just take the time to train youself in the science of training learn by reading quality material (I mean books by the highest reputed experts) to appreciate your body and how it adapts to the training stimulus.

In brief, the ideal arrangement is to plan out your whole season. I have also written an article on Periodization - the basics, which covers the essentials you need to do this. Typically, this should see you begin your season with a base fitness phase. This is the time for long-slow efforts. This can steadily progress to an increase in intensity, with a drop in volume. And then, finally, you can re-introduce the volume whilst maintaining your race intensity as you develop your endurance fitness for your main race.

The problem faced by so many age-group multisport athletes is the tempation to do everything exciting on the race calendar, or to enter events that friends are doing, rather than sticking to their own personal goals. This is often counter-productive and can even cause injuries.

So, be intelligent with your training, or pay someone else to be the brains, and you be the braun.

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Created: November 2012
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Lactate Threshold, Aerobic Conditioning, Triathlon Training, Base Fitness, Hiit, Sports Science