Whether you compete in cycling, running, triathlon, duathlon or multisport, the question often arises: how often should you test your lactate threshold (LT) or functional threshold power (FTP)? The answer depends on your goals, your training system and how you interpret the research. Below is a clear breakdown of three widely-cited experts, followed by how to apply this practically in your training plan.
1. Coach Joe Friel
Joe Friel recommends conducting a field test approximately every four to six weeks (for example at the end of each base or build phase) to recalibrate training zones (Friel, 2011). His protocol involves a 20- or 30-minute time trial. For example, for heart rate he advises running or riding alone for 30 minutes and using the average heart rate of the last 20 minutes as your lactate threshold heart rate (LTHR).
Key takeaway: Frequent threshold tests allow structured workouts to remain aligned with your current fitness level.
2. Dr. Stephen Seiler
Stephen Seiler emphasises training intensity distribution over frequent threshold retests (Seiler, 2010). His research shows that elite endurance athletes typically spend around 80 percent of their volume at low intensity (below the first lactate or ventilatory threshold) and only a small portion at moderate intensity, with a smaller portion at high intensity.
Key takeaway: Threshold values matter less than building a consistent training foundation through correct intensity distribution.
3. Dr. Andrew Coggan
Andrew Coggan proposes that FTP (functional threshold power) is a useful working benchmark but not a fixed physiological constant (Coggan, n.d.). He explains that assessing threshold “a few times per year, for example near the start of training, partway through the pre-competition period, and during the season” is likely sufficient for most athletes.
Key takeaway: Rather than testing on a strict cadence, adjust threshold when performance data show meaningful change.
Practical Application for Endurance Athletes
- Threshold testing can be treated as an optional feature of your training plan.
- Athletes who prefer structured calibration can test every 4–6 weeks (Friel’s model).
- Athletes who prefer monitoring via ongoing workout data and intensity distribution can test 2–3 times per year (Coggan and Seiler models).
Regardless of approach, design training zones and sessions with clear intention: structured workouts for those using threshold testing, and consistent low-intensity volume plus targeted high-intensity for those following intensity-distribution models.
Do you currently test your lactate threshold or FTP? If so, what schedule has worked best for you? If you don’t test at all, how do you track progress in your training instead?
References
Friel, J. (2011, May). The 30-minute test is easy. Really. Joe Friel Training. https://joefrieltraining.com/the-30-minute-test-is-easy-really/
Seiler, S. (2010). What is best practice for training intensity and duration distribution in endurance athletes? ResearchGate. https://www.researchgate.net/publication/46403553_What_is_Best_Practice_for_Training_Intensity_and_Duration_Distribution_in_Endurance_Athletes
Coggan, A. R. (n.d.). What is threshold power? TrainingPeaks. https://www.trainingpeaks.com/learn/articles/what-is-threshold-power/
