Trainer Jonathan Francis from One Performance UK explains how you can feel the burn and use it to go faster for longer.

I’m certain every triathlete out there, whether amateur or professional, has hit the wall during training or in competition. That feeling when they are close to complete fatigue and unable to sustain a given pace or level of exertion.

Lactate TrainingThe reaching of ‘the wall’ for every individual competitor will occur at a different point and it would be foolish to believe that you can completely remove the chances of this occurring.

However, it’s important to recognise how you can shape your training to delay this as much as possible. This will allow you to perform to your maximum and be the best triathlete you possibly can be.

Often, particularly when starting out, triathletes assume they need to run, swim, and cycle for long periods of time. While it is undeniably useful and necessary to build an endurance base across all three events, it is important to recognise that layering with lots of endurance training is only one part of the plan. A house isn’t considered complete once the foundations have been laid, it needs to be built upon. This is also the case for your training leading up to an event.

Triathlon training is not just about how far you can go, it’s about how hard you can go for how long. It’s about both endurance and intensity and both need to be trained independently. While endurance training is about finding a comfortable pace, stroke rhythm or cycling cadence, intensity training is about raising the level of exertion to points of discomfort and training the body to perform at this level for increasing amounts of time.

This brings us on nicely to the concept of thresholds and in particular the lactate threshold and how it plays a key role in triathlon performance.


All exercise requires energy. The energy required to move is supplied from the breakdown of something called adenosine triphosphate (ATP). The body has very limited stores of ATP and would use it up very quickly if our bodies didn’t have ways of resynthesizing it.

Simply explained there are three energy systems that produce energy:

  1. ATP – PC (phosphocreatine). Typically associated with very high power, explosive, short duration exercise
  2. Moderate power over a relatively short duration
  3. Low power for a long duration.

Remember all these systems are available and “turn on” at the onset of exercise. What determines which one (or two) is relied upon is the level of effort required. In the case of a triathlon we are talking about the glycolytic and aerobic systems.

While the aerobic system may well be the dominant system at play, huge amounts of energy is demanded across the course of a triathlon and when this demand can’t be met by the aerobic system alone, the glycolytic system picks up the slack. Technically termed ‘anaerobic’ (without oxygen) the glycolytic system is fast but it’s less efficient and produces less energy per unit of fuel burned than the aerobic system.


Simply put a threshold defines the point (or exercise intensity) when the energy source (carbohydrates / fats) your body is using to fuel that activity significantly changes. There are typically two thresholds or breakpoints that are passed during incremental exercise.


This is typically marked by the upper limit of exercise fuelled almost exclusively by aerobic metabolism (burning fat as fuel). Exercise intensity slightly above this level begins to increase concentration of lactate, however this typically stays at a constant level. Ideally for triathletes this occurs at a relatively high workload and would indicate a solid aerobic base.

All those miles on the road and metres in the pool will result in an increase to the aerobic base of a triathlete, this directly influences and improves the aerobic threshold. These improvements are significant as it would represent a greater ability to burn fat as fuel, sparing carbohydrate metabolism.


This is typically the point where there is a sudden and sustained increase in blood lactate concentration. Once you cross over this threshold and rely more heavily on anaerobic metabolism (fuelled by carbohydrate), you are essentially exercising on borrowed time as more lactate will be produced than can be cleared.

Improvements in anaerobic threshold will contribute towards greater rates/ amounts of lactate buffering or lactate clearance. This essentially is why appropriate amounts of training in and around your lactate threshold is so important. You are training your body to produce sustained amounts of power and effort whilst increasing the ability of the muscular system to resist fatigue.


Lactate TrainingLet’s take a look at what happens as blood lactate concentrations begin to peak in the blood. During anaerobic metabolism, carbohydrates are metabolised by the body. This breakdown of glucose produces lactate and hydrogen ions. The increased presence of hydrogen ions in the blood increases its acidity. This acidic environment affects the performance of your muscular system, ultimately to the point where you have to slow down or worse stop. The more work you can do before reaching this point (anaerobic threshold) the better.

Essentially being able to do more work at or under this threshold means sustaining a pace is easier and you will rely more heavily on the aerobic system. Ultimately this helps you save valuable energy for whenever you may need to increase exercise intensity.

Having a tremendous aerobic base is critical to any triathlete. However, hopefully now it becomes clear that it is also important to pay attention to and, where necessary, improve the lactate threshold as a means of significantly improving overall performance.

The aim therefore of lactate threshold training is to saturate the muscles in ‘lactic acid’ to train the body’s buffering mechanism to deal with it more effectively. Through this process (and with consistent exposure) we are also training the body to contract muscles repeatedly with force and quickness without building up too much lactate.

If muscles can increase workload or stress while maintaining a faster pace at aerobic levels you can stay under your anaerobic (lactate) threshold and perform at greater speeds for longer. A potentially winning combination.


Knowing how to improve anaerobic threshold all starts with the accumulation of data during some form of lactate testing procedure. This gathering of data will help provide a starting point and also something to measure your success against, showing an increase pace or power at threshold or an improved heart rate recovery.

You can assume that your anaerobic threshold typically falls between 75-85 per cent of Max Heart Rate (MHR). Therefore, a simple heart rate monitor might be the only thing you might need to help construct some training parameters.


Consistency is the key to improving performance at lactate threshold. Triathlete’s should aim to accumulate a lot of intervals completed at steady workload, which helps place the appropriate amount of stress or load on the system. Since you can’t spend a lot of time working above threshold, these training intervals have to be at an intensity just below your threshold (5-10%) intervals, for running and cycling should progress from relatively short (5min) to longer (20min) durations over the course of a training cycle with recovery intervals set at approximately one third or half the time of the interval.

The initial focus of the training should be centred on accumulating time with shorter intervals and multiple repeats before moving on to longer intervals with fewer repetitions. Progressing your training sessions throughout the training cycle is determined by the individual triathlete. Length of interval and recovery time are the two most commonly manipulated variables. Both could be adjusted over the course of a training cycle, although it’s advisable to focus on changing just one.

It is worth recording, charting and analysing all threshold runs. Distance covered, peak/average heart rates, recovery heart rates as this is all useful data when assessing the success of the training cycle. It requires physical and mental exertion to maintain the quality of interval and work being done. As a result of this some common physical characteristics might be experienced, these shouldn’t be chased but may signify that exercise intensity is appropriate.

Examples include, mentally taxing, sensation of moderate-high leg effort/ fatigue and continuous conversation difficult due to the depth and frequency of breathing. Remember adaptation (progress) is unlikely to occur without the presence of sufficient recovery. This type of training is taxing on the body, therefore it’s best to put a light endurance/active recovery day in between lactate training days.

Training to improve your thresholds is a valuable and sometimes entirely necessary process. It’s another factor that helps triathletes, recreational all the way to elite, ultimately understand, embrace and utilise the training methods that can limit their competitive performance.

While improving your performance at lactate threshold might indeed make a difference if at some point the race comes down to a sprint, the real importance of all the training is an increased resistance to fatigue alongside and increased ability to ‘buffer’ the effects of increasing lactate production.

Don’t hit the wall, drive right through it!


Session 1: 3 x 5mins @ target heart rate with 2.5minutes recovery (15mins work)

Session 2: 4 x 5mins @ target heart rate with 2.5mins recovery (20mins work)

Session 3: 3 x 6mins @ target heart rate with 2.5mins recovery (18mins work)

Session 4: 4 x 6mins @ target heart rate with 2.5mins recovery (24mins work)


First published in Triathlon Plus Magazine, June 2016