Original episode & show notes | Raw transcript
This document provides a detailed analysis of the key ideas discussed in the “Empirical Cycling Podcast” regarding Functional Threshold Power (FTP). It aims to elaborate on the conversational points from the transcript, presenting them in a structured, educational format suitable for an intelligent student audience.
The podcast begins by addressing the common challenges and fallacies associated with standard FTP testing protocols. While tests are designed to be objective measures of fitness, their execution is often fraught with subjective and logistical issues.
A significant theme is the psychological stress that testing induces, which can invalidate the results. This isn’t limited to novice athletes; it affects cyclists at all levels.
Test Anxiety: Many athletes experience more nervousness for a fitness test than for a major race. This anxiety stems from the test being perceived as a “day of truth,” a final judgment on the effectiveness of their training and a potential measure of wasted time.
Emotional Energy Expenditure: The mental and emotional energy spent worrying about an FTP test can be significant. The podcast argues this energy is better invested in productive training that builds fitness.
Pressure and Rigid Plans: Pre-scheduled tests in “canned” training plans can create a looming sense of pressure, potentially leading athletes to over-exert themselves in the workouts leading up to the test, resulting in fatigue and a poor test outcome.
Even with a perfect mindset, logistical issues can compromise a test.
Inadequate Rest: Athletes often mismanage their rest period. A proper test requires being fresh, but not so rested that the legs feel “stale.” An athlete must understand their individual response to rest to time a test effectively.
Misinterpreting “Bad Legs”: Athletes often feel obligated to proceed with a test even if they feel poor during the warm-up. A core principle of effective training is flexibility; a training plan is a “living document.” If the Rate of Perceived Exertion (RPE) is unusually high during the warm-up, the correct decision is often to postpone the test rather than force a poor performance.
Environmental Factors: Issues like finding a suitable, uninterrupted stretch of road, or the physiological differences between indoor (e.g., overheating) and outdoor riding, add variables that can skew test results.
The podcast emphasizes a nuanced view of FTP, moving beyond the idea that it is the sole determinant of cycling success.
For competitive racing, a high FTP is described as “necessary but not sufficient.”
The “Ticket to Entry”: A strong FTP gets you to the starting line with the physiological capacity to be competitive. It allows you to stay with the group during hard sections.
Not a Guarantee of Success: It does not guarantee a result. Racecraft, tactics, positioning, energy conservation, and bike handling are equally critical. Even in a pure time trial, factors like pacing strategy and aerodynamics are paramount.
FTP has become a vanity metric, analogous to “how much you bench press.” This has led to the popularity of test formats that can inflate the FTP number.
Mathematical Lubrication: Short-duration tests, like ramp tests or 8-minute tests, heavily factor in an athlete’s anaerobic capacity. By applying a fixed percentage (e.g., 75% of the best 1-minute power in a ramp test) to a supra-threshold effort, they can overestimate an athlete’s actual sustainable, aerobic threshold power, especially for anaerobically gifted riders.
The Danger of an Inflated FTP: Training with an inaccurately high FTP leads to consistently failed workouts, accumulating excessive fatigue, and ultimately hindering progress. The podcast strongly advocates for consistency over heroics; it is far better to complete workouts at a correct, albeit lower, intensity than to fail them at an inflated one.
When formal testing fails or proves unreliable, the podcast proposes two highly effective, RPE-based methods to determine a practical, usable FTP.
This is the preferred method for an athlete who has a good sense of their body but is struggling with the pressure of formal testing.
Protocol: Perform a standard threshold workout, such as 2x20 minutes or 3x15 minutes, with 5-10 minutes of rest between intervals. Crucially, all power and heart rate feedback is disabled. The athlete paces purely on feel (RPE).
Rationale: By removing the external pressure of hitting a specific number, the athlete can ride at a power that is genuinely sustainable for that duration. This method bypasses test anxiety and taps into the athlete’s intuitive sense of effort.
Outcome: For an experienced athlete, the average power produced during these intervals is often an extremely accurate and functional representation of their FTP. This method can work both ways: confirming an FTP after a bad test, or revealing that a “crushed” test produced an unsustainably high number.
This method is ideal for athletes who are less in-tune with their RPE and need to learn the physiological sensations associated with crossing the threshold.
Protocol: Perform a series of intervals of the same duration (e.g., 10 minutes), starting ~60 watts below the suspected FTP. With each subsequent interval, increase the power by a small, fixed amount (e.g., 15 watts).
Rationale: This “random walk” method allows the athlete to methodically approach and then cross their threshold. The goal is to identify the precise point at which the physiological state shifts from stable to unstable.
Outcome: The athlete will notice a distinct change in sensation as they move from one interval to the next. The final interval that felt sustainable is likely at or just below threshold, while the first interval that felt unsustainable, where breathing became ragged, was just over.
Understanding what you are feeling is key to using RPE-based methods effectively.
At or Below Threshold: Effort is high, but the system is stable.
Breathing: Labored but controlled. You are aware of your breathing, but it is not running away from you.
Legs: A sensation of muscular effort or a “burn” may be present, but it feels manageable and does not escalate uncontrollably.
Above Threshold: The system becomes unstable and rapidly fatigues.
Breathing: Becomes ragged and uncontrolled. There is an urgent, involuntary need to breathe harder that cannot be suppressed.
Legs: You can often feel a distinct increase in muscular strain.
These sensations are direct reflections of profound physiological shifts.
Motor Unit Recruitment (EMG Breakpoint): As you exceed your FTP, your body’s demand for ATP (energy) outstrips its ability to produce it aerobically. To compensate, the brain must rapidly recruit larger, more powerful (but less sustainable) motor units. This non-linear increase in neural drive and muscle fiber recruitment is what an athlete feels as a sudden increase in effort.
Metabolic Shift: Above threshold, the energy deficit is covered by anaerobic glycolysis. This process is highly inefficient, yielding only ~2 ATP per glucose molecule compared to the ~34 ATP from aerobic metabolism. This inefficiency causes the engaged motor units to fatigue very quickly, forcing the recruitment of even more units in a cascading failure.
An athlete’s physiological makeup influences their perception of threshold.
Anaerobically Strong Athletes (Sprinters): Possess a large anaerobic capacity. They can buffer the metabolic consequences of being slightly over threshold for a longer duration. This can “dupe” them into thinking an unsustainable effort is sustainable. For them, fatigue may arrive suddenly and catastrophically. For the “sneak up” method, they may require longer intervals (10-15 min) to truly feel the unsustainability.
Aerobically Strong Athletes (Time Trialists): Have a smaller anaerobic capacity. They will experience the negative sensations of being over threshold much more quickly and distinctly, making it easier for them to pinpoint their limit.
Finally, the podcast touches on using software and applying these concepts in a coaching context.
Modeling Software (WKO5): Modeled FTP (mFTP) can be a useful guide, but it is only as good as the data fed into it. For an accurate model, the training data must include maximal efforts across a range of durations. A “V-shaped” power curve (from only doing long, easy rides and short sprints) will yield a poor model. Adjusting the look-back period (e.g., from 90 to 45 days) can provide a more current fitness snapshot.
Post-VO2 Max Block Fatigue: It is common for FTP not to increase immediately following a hard block of VO2 max training. This is often due to residual fatigue. Rather than forcing another test, the better approach is to return to sub-threshold training and allow the fitness adaptations to manifest, which they will if the training was effective.
Trusting Athlete Intuition: With a very small handful of highly experienced athletes, a coach can allow them to subtly increase the power of their threshold intervals based on feel. This allows for an organic progression of FTP without the need for constant formal testing.
Embrace Consistency: The overarching message is to prioritize training consistency based on a realistic and functional threshold. It is better to round your FTP down by 5-10 watts and complete all your workouts than to round up and struggle. Small fluctuations in power are often within the margin of error of a power meter anyway.