Establishing Thresholds for Optimal Triathlon Training With TRIQ


When performing any endurance training, the adaptive response of the body is highly dependent on the intensity of exercise or type of endurance workout you are performing. We also know that using different types of training to work in all areas of your physiology is essential for success in triathlon. Some examples of the physiological performance parameters targeted in this approach include basic endurance and durability, aerobic threshold power/pace, anaerobic power/pace, fat oxidation, carbohydrate utilization, economy and VO2max, to name but a few. The importance of each of these factors as a whole is known as the "determinants of performance". The importance of each of them changes according to your target triathlon race distance. For example, for a sprint distance race, a high VO2max and the anaerobic threshold is essential.

Conversely, having a high aerobic threshold and fat oxidation is essential for a long-distance triathlon event such as IRONMAN®. Therefore, training at the correct intensity is of utmost importance to build these different determinants of success in your triathlon training. For example, low-intensity endurance training elicits adaptation by promoting fat oxidation and structural changes at a muscular level, such as increased mitochondrial content and capillarization. Conversely, training at a high intensity around the anaerobic threshold is known to generate adaptations relevant to acid-base balance and the ability to re-uptake and utilize lactate as a fuel source during exercise. Two very different and specific adaptations! This shows that it is very important for all athletes, but especially for triathletes, to pay attention to what is being trained at what intensity in their training and the individual exercises in order to know which physiological property of the body is being improved.

Relative Exercise Intensity

When it comes to exercise physiology and training, there are two types of intensity. These are absolute exercise intensity and relative exercise intensity. Absolute exercise intensity is precisely that; for example, 300 w is 300 w, regardless of your individual ability. Comparatively, relative exercise intensity refers to a specific physiological value representing the athlete's individual ability or capacity. Examples of these reference points include VO2max, maximum heart rate, anaerobic thresholds (heart rate, power, pace) and aerobic threshold (heart rate, power and pace). Typically, relative exercise intensity is calculated as a % of a specific value. For example, we take two athletes, A and B. Athlete A has a threshold power of 300 w, and athlete B has a threshold power of 260 w. Let's take 80% of both these values (240 w and 208 w) and set them to ride at this for 1 hour. By doing this, the relative intensity and physiological response to training are the same for the two of them. When it comes to prescribing training, this is a critical consideration. Due to this fact, especially in endurance training, it is important to know your own performance and thus adjust the intensity of the exercises to it.

The Anaerobic Threshold

At TRIQ, training is set and individualized according to every athlete's relative exercise intensity. For us, the boundary or base value used for this is the individual Anaerobic Threshold. So what is that? The Anaerobic Threshold refers to the intensity at which we transition from 'steady-state' to 'non-steady-state' metabolic responses to prolonged exercise. In a metabolic steady-state, exercising at a constant power or pace will produce stable responses. These include muscle and blood lactate concentrations, acid-base balance, phosphocreatine availability, and oxygen consumption (VO2) which will plateau and stabilize. However, when we are in a metabolic non-steady state, the exercise intensity is high enough that these responses can no longer stabilize. Accordingly, muscle and blood lactate concentrations progressively rise. In addition, we become increasingly acidic, and the volume of oxygen consumed (VO2) continues to increase, eventually to our maximum rate. Therefore, the "Anaerobic Threshold" defines the boundary between exercise intensities at which these steady-state and non-steady-state responses are observed. These can also be referred to as the boundary between heavy- and severe-intensity domains. Finding out this anaerobic threshold is essential for athletes, as this knowledge is the basis for individual training and adapted workouts and exercises.

Training Intensity Distribution

Of course there is more to good training prescription than knowing your threshold. At TRIQ, we also ensure our athletes train with the correct distribution of training intensity. This means training is sustainable, with the correct balance of low (70-80%) and high intensity (20-30%) training. Again, this is where relative intensity is critical. Get this wrong, and you could be training at an intensity that’s too low when you should be training at a high intensity. Or worse, training at a too high intensity when you should be training at a low intensity. The latter is critical, as too much back to back high-intensity training can easily lead to burnout, or what is commonly known as overtraining. Therefore, knowing your individual Anaerobic Threshold is very important to both train correctly AND maintain sustainable and consistent training. All that said, let’s talk about ways to measure the Anaerobic Threshold, from the most simple at-home method to the more complex laboratory-based processes.

Different Tests to Measure the Anaerobic Threshold

Critical Swim Speed Test (Swimming)

Critical Swim Speed is an estimation of the speed associated with the Anaerobic Threshold. Although some also suggest that it’s the maximal maintainable pace for 1500 m. While this measure may not be totally exact, it's a simple and effective method to guide your swim training. Moreover, the calculation of an athlete’s CSS is easy to do and also repeatable. The CSS test consists of two swims – 200m and 400m time trials – so as fast a speed as can be maintained for those distances. The 400m time trial test is done first, and it is advisable to rest between the tests with some easy swimming. The 200m time is then subtracted from the 400m time and the result is divided by 2. This gives you your critical swim speed pace per 100 meters. We also advise a short warm-up before the first 200m swim. If you conduct this test and know your 200m and 400m swim times, you can use our calculator to simply fill in your values. You can then also enter the result in the TRIQ app to get even better training prescriptions. Once you have completed the critical swim speed test, you will know important data not only about your endurance, but also specific values about your swimming speed and your swimming endurance.

Functional Threshold Power Test (Cycling)

Many endurance athletes do not have regular or affordable access to laboratory facilities. Therefore, many athletes and coaches have adopted the field-based functional threshold power (FTP) test. The FTP refers to the maximum work rate that can be sustained for 60 min. The FTP concept is derived from studies that showed strong correlations between average power during a 60-min time-trial and 40-km time-trial performance on the road and the Lactate Threshold (Anaerobic Threshold). Due to the almost unreasonable demands associated with performing an 'hour of power'. The 20-min FTP test was proposed, in which 95% of the best-effort power of 20 min is accepted as FTP (FTP20). However, this 'correction factor' was not research-derived. Recently, 90% of 20-min power has been shown as a better estimate of 60-min power. Many online platforms such as Zwift help guide you through the protocol of an FTP test and then calculate your FTP for you. Alternatively, go here to plug in your best 20-minute power value and calculate your FTP. With the data from the FTP test, not only can you learn about your endurance and adjust your training accordingly. Your data is especially beneficial in conjunction with the TRIQ app, as the app's AI can create individualized training plans according to your performance data generated by the functional threshold power test.

Jack Daniels VDOT Test Method (Running)

The VDOT method calculates the Anaerobic Threshold based on recent race performances. It was developed by the legendary exercise physiologist and running coach Jack Daniels. This is a prevalent method amongst runners to determine how fast to perform particular types of training (e.g. long slow distance, interval pace, marathon pace) and threshold pace. This test and its results is important for athletes to adjust their training plans and no their performance Data without spending a lot of money for laboratory tests. Although this method has not been scientifically validated in the laboratory, many runners find the VDOT system accurate and easy to use. The VDOT is established by running a time trial. From this, you can establish your own "individual" VDOT and then further select a specific % for various relative exercise intensities, including the anaerobic threshold. We recommend a 5 km time trial as the best method to establish your VDOT. This is a great distance as it's long enough to be accurate, but not too long to disturb your training routine. A local 5 km race or time trial is a great place to start. When doing so, ensure the race or time trial on a (relatively) flat course, with sound footing and good weather conditions. Poor weather or difficult terrain will negatively affect your time and result in a lower VDOT and affect your long-term training.

Critical Power Test (Cycling and Running)

Critical power (CP) is a concept analogous to the Anaerobic Threshold. It uses plots of an individual's power-sustainable duration relationship to estimate critical power (or velocity), which is defined as the asymptote of this curve. In a laboratory setting, these curves are constructed using three-to-five constant-load time-to-exhaustion trials in the severe-domain (i.e. above anaerobic threshold), lasting ~2-15 minutes. These testing procedures have been shown to produce Anaerobic Threshold estimates that distinguish steady and non-steady metabolic responses.
CP via Tree-Minute All-Out-Test (Cycling and Running).
This rather gnarly alternative assessment method is the "three-minute all-out test". The CP test has been found to estimate the anaerobic threshold some success when performed in laboratory environments. This test involves three minutes of non-paced, all-out exercise with continuous measurement of power. Critical power is defined as the average power during the final 30 s of the test.

Incremental Step Test (Swimming, Cycling and Running)

A very common method used in laboratories to estimate the Anaerobic Threshold is the incremental exercise test, where blood lactate concentration is measured at a range of work rates and then plotted against power or pace. Whilst there is no universally accepted metric of turning this data into an estimate of the threshold, several exist. The methods used for estimating the Anaerobic Threshold are trying to identify the point on the curve at which blood lactate begins to rise exponentially against exercise intensity.

Ramp Tests (Cycling and Running)

Many athletes also perform ramp tests to estimate their 'threshold' (Anaerobic Threshold). In these tests, power is increased by a fixed amount every minute. The athlete hangs in as long as they can last amidst the progressively increasing power demands. Typically, power at threshold is estimated using a percentage of the final power output achieved (~75%). These tests are therefore similar to what most laboratories will use for measuring VO2max, as exhaustion in this type of protocol will usually coincide with the attainment of VO2. From a scientific standpoint, the accuracy of these tests for estimating the anaerobic threshold remains untested. However, these types of tests may be more beneficial for inexperienced athletes who have trouble effectively pacing time-trial based tests (e.g. 20 min FTP). Similarly to the FTP tests, online platforms such as Zwift help guide you through ramp test protocols.

Establishing Heart Rate Thresholds Based on Testing Data

As well as power and pace to prescribe exercise intensity, heart rate (HR) zones are also critical. This is particularly important for your endurance-based workouts. Keeping HR in check, below the aerobic threshold, is vital for attaining the correct training adaptation and keeping you fresh for higher intensity workouts.

For this, you can use your average HR in a maximal 45-60 minute effort (e.g. 15 km running at race pace or 40 km cycling time trial). You can also take a percentage of the performance tests outlined above (20 min FTP and 5 km running). Both of these tests will generally overestimate a true anaerobic threshold HR. However, how many percent off the estimation is, depends on your HR kinetics, meaning how fast your HR rises at the onset of an exercise and attains a steady state. The best estimate is subtracting either 3% or 5% of the average HR measured during the 20 min FTP or 5 km run. Use -3% if your HR takes longer to achieve a quasi-steady-state (>7 minutes). Use -5% if your HR is fast to complete a quasi-steady-state (<7 minutes). For example, 166 bpm for 20 minutes or a 5 km run would result in 158 bpm (with -5% for fast HR kinetics) or 161 bpm (with -3% for slow HR kinetics). Once you have established these values, be sure to set them correctly in the app.

Which Anaerobic threshold test is the best? A Summary

Establishing the personal Anaerobic Threshold to ensure the correct relative exercise intensity for all your TRIQ training sessions is critical for optimal and sustainable training. In the TRIQ app, you can set this manually or during the onboarding process. If you don't know your threshold, just get involved with some of your own testing. ​​All these tests serve one purpose, to find out your relative exercise intensity and to use this data as a basis for a balanced and individual training. No matter which of the tests you use, the more regularly, and accurately they are performed, the more effective your triathlon training will be. The TRIQ app takes on the role of a processor that processes your data and draws conclusions about the intensity and difficulty of your workouts and exercises. We recommend the CSS, FTP, and 5 km (VDOT) testing as the easiest and most repeatable ways to establish your swim, bike, and run threshold. Happy training!

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