Science and Secrets Pt. 2: How to Set Your Training Zones

By Danielle Farinella

Am I doing this right?

It’s February, and you’ve been training with specific goals in mind for each session: increasing aerobic capacity, improving oxygen transport, etc. But how do you know if you’re executing the workouts in the correct zone? (If you’re unfamiliar with Training Zones, see Part 1 of this series on the The Boathouse Blog!)

How to initially set up your zones (a few methods):

There are a few different ways to set up your zones, each with its own pros and cons. These are briefly described below, with more detail in Table 1:

1. Lactate testing (gold standard): For this test, you would perform increasingly faster intervals, taking a blood sample and measuring your blood lactate quickly between intervals. Analysis with software like Ergonizer will reveal the wattage of Lactate Threshold 1 (below which is UT2, above which is UT1) and the wattage of Lactate Threshold 2 (below which is UT1, above which is TR/AN, and near which is AT). This is the gold standard, since it directly measures lactate, which is a direct measurement of anaerobic system activity. All other methods below rely on generalization and do not directly measure this.

2. Jensen testing + Critical Power: Jensen testing was originally developed to identify weaknesses in physiology. This requires doing a testing battery and comparing each result to each other to identify weak areas (See Table 2). However, this method in itself doesn’t calculate your training zones. So you will want to use this in tandem with a Critical Power calculation, where you’ll input your Jensen Testing scores. This requires some math, so I recommend just using an online calculator to calculate Critical Power. Critical Power (CP) is defined as the “fatigue threshold” where exercise becomes unsustainable (Poole, 2016). This is conceptually similar to Anaerobic Threshold and LT2, but is defined by true physical ability to continue, as opposed to a blood lactate concentration. Once you have calculated CP from the Jensen Testing, you can calculate where the other zone boundaries likely are (see Table 1).

3. Functional Threshold Power testing: This test is used to estimate the power at which lactate removal roughly equals its production (aka LT2 or Anaerobic Threshold). From there we can calculate where the other zone boundaries likely are (see Table 1).

4. Heart rate reserve: This method works by calculating percentages of your heart rate reserve (Heart Rate Reserve = Maximum - Resting) and defining your zones by those heart rates. However, it comes with a few caveats. You must know your real max HR, not the 220-age value, since max HR has high variability (Pereira-Rodríguez Javier Eliecer, 2018). Additionally, heart rate can be impacted by things like temperature, sleep quality, stress, etc, which decouples HR from what is going on in the body metabolically. However, this can be a good fallback for those who feel like the generalized wattage guides from the CP and FTP testing do not fit them well.

5. 2k split guides: This method is very common, mainly because it doesn’t require doing any math, and is easy to apply on large teams. These are general estimations of zones based on number of splits above or below 2k pace (See Table 1). To convert these for a 1k result, add 5 splits. There are plenty of very good teams which use this method or similar, which speaks to the impact size of training frequency/consistency (large) vs having the perfect zones set (small). With that said, this is likely the least accurate method, since the 2k doesn’t measure any particular physiological attribute, it just happens to be our racing distance. Additionally, (*pulls out soap box*) because the relationship between watts and splits is not linear, this means that 5 splits for faster athletes is a much higher percentage of their 2k wattage than for slower athletes. This makes workouts below 2k harder for faster athletes, and workouts above 2k harder for slower athletes. To avoid this, I would recommend using a percentage of 2k wattage.

TABLE 1: Deriving Zones From Testing

Method	Lactate testing (gold standard)	Jensen testing + Critical Power	FTP testing	Heart rate reserve	2k split + X
Testing Protocol	7x4’, 1’ rest, increasing wattage, take lactate measurement during each rest. Plot lactate against wattage at each step.	Perform a 10 sec, 60sec, 2k, 6k, and 60min test (on different days). Calculate critical power, and plot test wattages on graph to check the curve.	Perform 20’ as fast as possible. Record average wattage.	Measure your resting heart rate when you wake up and your maximum using a step test or race-pace effort.	Row 200m as fast as possible.
UT2	Wattage @ <2mM lactate	56-75% of Critical Power wattage	55-65% of FTP wattage	59-67% of HRR	2k split + 25-35
UT1	Wattage between 2mM lactate and 4mM lactate	76-90% of Critical Power wattage	66-80% of FTP wattage	67-75% of HRR	2k split + 15-20
AT	Wattage @ 4mM lactate	91-105% of Critical Power wattage	81-100% of FTP wattage	75-85% of HRR	2k split + 5-15
TR	Wattage between 4mM and 8mM lactate	106-120% of Critical Power wattage	100-120% of FTP wattage	85-100% of HRR	2k split -2 to 2k split +5
AN	Wattage @ 8mM lactate	120%+ of Critical Power wattage	120%+ of FTP wattage	HR is not a good measure of AN effort	Faster than 2k -3
Danielle’s opinion	Great! (#1 ranking) Pros: Directly measures (as much as possible) the activity of your energy systems and your ability to clear lactate.	Good! (#2) Cons: can have high accuracy variability from person to person (Morgan, 2018), can overestimate AT (Dotan, 2022).  Pros: Provides more information about your weaknesses.	Good (#3): Cons: can have high accuracy variability from person to person (Jeffries, 2021)	Fine (#4) Pros: helpful to use to sanity check wattage-based zones.  Cons: Easily influenced by outside factors, and is not necessarily correlated with metabolism (Meixner, 2022)	Fine (#5) Pros: Logistically easy for large teams Cons: Does not account for the non-linear relationship between split and watts.

TABLE 2: Jenson Testing Weakness Identification

Test Portion	10s	60s	2k	6k	60min
Expected % of 2k watts	173%	153%	-	85%	76%
Possible Interpretation	If result is below this percentage, incorporate more strength training	If result is below this percentage, incorporate more anaerobic intervals	-	If result is below this percentage, incorporate more time at anaerobic threshold	If result is below this percentage, incorporate more time in UT1 and UT2

Sanity checking your zones:

Once you’ve set up your zones, you need to sanity check them. You are your own unique athlete, and the majority of these methods use generalizations based on the whole human population. You should expect that these zones won’t be perfect (Morgan, 2018; Jeffries, 2021).

Sanity checking by heart rate

One way to sanity check our zones is to look at the behavior of the heart rate in the zone over a series of practices. For UT2, your heart rate should rise in the first 10’, but then remain steady for the rest of the piece*. If your heart rate continues to climb, you may need to shift the zone lower. This may indicate that your LT1 is a lower percentage of LT2 than estimated.

* If you are newer or returning to endurance training, your heart rate may continue to rise, and this is normal.

For TR, we should expect our heart rate to be at >90% of max for the majority of the workout. If your TR paces are not challenging enough to raise your heart rate to these levels, you may need to shift your zone faster. This may indicate that your LT2 (AT-adjacent lactate threshold) is a higher percentage of your VO2 max than estimated.

Sanity checking by feel and outcome

Do you feel relatively recovered after a UT2 session, or are you sore the next day? Did your splits in each zone get easier to hold after a few months? These are examples of questions we can ask to understand if our zones are “working”. If you don’t have access to lactate testing, it may take some trial and error to find a zone structure that works for you!

How do I know when to do what sessions? 

When should I rest, and when should I continue?

Great questions! In the final, upcoming part of this series, I’ll explain how to track your personal data, analyze it, and “engineer” your training to be as fast as possible on race day.

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Danielle Farinella is an assistant coach for the TRRA AA-Masters team and a 5th-year Molecular Biology PhD student at Pitt. In her free time, you can find her training with the TRRA Open Racing team or reading about exercise physiology.

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Works cited:

\Jeffries, Owen1; Simmons, Richard2; Patterson, Stephen D.2; Waldron, Mark2,3. Functional Threshold Power Is Not Equivalent to Lactate Parameters in Trained Cyclists. Journal of Strength and Conditioning Research 35(10):p 2790-2794, October 2021. | DOI: 10.1519/JSC.0000000000003203 

Dotan, R. A critical review of critical power. Eur J Appl Physiol 122, 1559–1588 (2022). https://doi.org/10.1007/s00421-022-04922-6

Poole DC, Burnley M, Vanhatalo A, Rossiter HB, Jones AM. Critical Power: An Important Fatigue Threshold in Exercise Physiology. Med Sci Sports Exerc. 2016 Nov;48(11):2320-2334. doi: 10.1249/MSS.0000000000000939. PMID: 27031742; PMCID: PMC5070974.

Pereira-Rodríguez Javier Eliecer., et al. “Correlation and Difference between the Maximum Cardiac Frequency and the Formulas of Tanaka and 220-Age”. EC Cardiology 5.10 (2018): 666-674.

Meixner, B., Filipas, L., Holmberg, H. C., & Sperlich, B. (2025). Zone 2 Intensity: A Critical Comparison of Individual Variability in Different Submaximal Exercise Intensity Boundaries. Translational Sports Medicine, 2025(1), 2008291. https://doi.org/10.1155/tsm2/2008291