Original episode & show notes | Raw transcript
This document provides a comprehensive exploration of the principles of Functional Threshold Power (FTP) training as detailed in the provided transcript. We will deconstruct the physiological underpinnings of FTP, analyze the shortcomings of common training methodologies, and present a systematic, effective approach centered on the principle of progressive overload.
At its core, Functional Threshold Power (FTP) is defined as the highest power output an athlete can sustain while maintaining a physiological steady state. The podcast equates this to the Maximal Lactate Steady State (MLSS), which is the highest exercise intensity at which the rate of lactate production in the muscles equals the rate of lactate clearance from the blood.
Why is this important?
Metabolic Ceiling: FTP represents the upper limit of your purely aerobic capabilities. It is the highest metabolic load you can handle continuously before fatigue begins to accelerate rapidly.
Physiological Shift: Exercising even slightly above FTP causes a significant quantitative and qualitative shift in your metabolism. Your body’s reliance on anaerobic energy pathways increases dramatically, leading to a rapid accumulation of metabolic byproducts and a much shorter time to exhaustion.
Relevance Beyond Steady State: While it’s a measure of steady-state effort, FTP is fundamentally important even for intermittent, high-intensity sports (e.g., criterium racing, cyclocross, team sports). A higher FTP means that the hard, repeated efforts are performed with a smaller anaerobic contribution, allowing for better recovery between efforts and greater sustainability over the course of an event. In essence, a higher FTP makes hard efforts feel easier and more repeatable.
A common approach to FTP training is the “classic” 2x20 minute interval workout, often performed at or just below a predetermined FTP value (e.g., 95-105% of FTP). While initially effective for many, this method often leads to a performance plateau.
The core issue is a failure to adhere to the principle of progressive overload. If an athlete repeatedly performs the exact same workout (2x20 at 250 watts) week after week, their body will adapt to that specific stress. Once adapted, the workout is no longer a sufficient stimulus to trigger further physiological improvement. It’s the equivalent of a weightlifter lifting the same weight for the same number of reps and sets indefinitely and expecting to get stronger.
Progressive Overload is the foundational concept that to improve any physiological capacity, the body must be subjected to a stimulus that is greater than what it is accustomed to. This forces the body to adapt and become stronger or more efficient.
The podcast illustrates this with two excellent analogies:
Strength Training: A novice lifter on a program like “Starting Strength” adds a small amount of weight to the bar each session. This constant, incremental increase in load is a perfect example of progressive overload. When this linear progression is no longer possible, more complex variables are manipulated (e.g., adding reps, adding sets, changing exercises) to continue providing a novel stimulus.
Caffeine Tolerance: One cup of coffee provides a significant stimulus initially. Over time, the body adapts, and that same dose produces a diminished effect. A greater stimulus (more coffee) is required to achieve the original effect.
In FTP training, this means you cannot simply repeat the same workout. You must systematically increase the demand over time.
The podcast highlights a study on masters endurance runners to illustrate a successful application of progressive overload.
The Subjects: Well-trained runners (average half-marathon time of 1:23) who had plateaued.
The Intervention: They replaced two of their weekly steady-state runs with interval sessions performed at their MLSS velocity (their running “FTP”).
The Progression: The key was not increasing the intensity (velocity), but systematically increasing the duration of the work performed at that intensity. Over six weeks, the total time spent at MLSS per session increased from 30 minutes to 60 minutes.
Week 1: 30 mins total (e.g., 3x10 or 2x15)
Week 2: 36 mins total (e.g., 3x12 or 2x18)
…to Week 6: 60 mins total
Key Physiological Outcomes:
Increased FTP: Their velocity at MLSS increased from 13.8 to 15.2 km/h. They became faster at their threshold.
Increased Time to Exhaustion (TTE): Their ability to sustain their new, higher FTP increased dramatically, from 44 minutes to 63 minutes. This is a critical, often overlooked, dimension of FTP.
Increased VO2 Max: Their maximal aerobic capacity saw a small but significant increase. Importantly, their FTP remained at a high percentage of VO2 max (~85%), indicating that the improvements were primarily in their sustainable power, not just their ceiling.
Improved Fat Metabolism: The Respiratory Exchange Ratio (RER) at their new FTP remained the same (~0.93). This implies that at their old FTP power, they were now burning significantly more fat. This “fat-sparing” effect is hugely advantageous, as it preserves finite glycogen stores for higher-intensity efforts.
The central thesis of the podcast is that FTP is not a single number (e.g., “my FTP is 300 watts”). It has two dimensions:
Intensity: How many watts?
Duration: For how long? (This is the Time to Exhaustion, or TTE).
To improve FTP, you must “chase” one or both of these dimensions. The podcast argues forcefully that chasing duration is the more practical, reliable, and effective method.
Why prioritize extending duration?
Measurability: Small weekly gains in FTP (e.g., 2-3 watts) are often smaller than the margin of error of most power meters (~1-2%, or 3-6 watts at 300w). It’s difficult to know if you’re truly working at a higher intensity. In contrast, adding 5 minutes to your total interval time is an unambiguous and accurate increase in workload.
Accomplishability: Trying to force a higher power output every week can quickly lead to failed workouts, as your physiology may not be adapting that quickly. Extending duration at a known, manageable power is far more sustainable and builds aerobic resilience.
Stimulus Specificity: The primary adaptations for aerobic fitness (mitochondrial biogenesis, capillary density, etc.) are driven by volume and time spent challenging the system. By extending the duration at or just below FTP, you are maximizing the time spent providing this specific stimulus. Going significantly over FTP changes the stimulus and shortens the time you can spend providing it.
Establish a Baseline: Start with an FTP test to determine not only your power at threshold but also your Time to Exhaustion (TTE) at that power. A 40-minute test is a good starting point.
Start with Manageable Chunks: Base your initial interval structure on your TTE. If your TTE is 40 minutes, a good starting point is 4x10 minutes at FTP with short rests (e.g., 3-5 minutes). The total work time (40 minutes) matches your known capability.
Progress by Extending Time: The primary method of overload should be increasing the total time at FTP.
4x10 (40 min) -> 3x15 (45 min) -> 5x10 (50 min) -> 4x12 (48 min) -> 2x20 (40 min, but more continuous) -> 2x25 (50 min) -> 3x20 (60 min).Progress by Reducing Rest: Once you can handle a significant volume of work (e.g., 60 minutes), a secondary progression is to reduce the rest periods between intervals. This makes the workout more continuous and challenging, eventually leading to single, long intervals (e.g., 1x40, 1x60).
Introduce Metabolic Bursts: To increase the metabolic load without abandoning the “at-FTP” intensity, incorporate bursts or accelerations.
Example Workout: During a 2x20 interval, perform a 10-second, high-power surge every 4-5 minutes, then immediately settle back to FTP.
Benefit: This simulates race-day demands and increases the overall metabolic stress of the workout, providing a novel stimulus to drive adaptation, while also breaking up the monotony of long intervals.
By following this framework, you ensure that your training always provides a sufficient stimulus for adaptation, systematically pushing your FTP both up (in watts) and out (in duration), and breaking through the plateaus that plague static training plans.