Original episode & show notes | Raw transcript
Functional Threshold Power (FTP) is arguably the most critical performance metric for an endurance cyclist. It represents the highest power output you can sustain in a quasi-steady state for a prolonged period, typically around 60 minutes. Physiologically, it marks the inflection point where the rate at which your body produces lactate (a byproduct of anaerobic metabolism) begins to exceed the rate at which it can clear it. This metabolic tipping point is often referred to as the Maximal Lactate Steady State (MLSS).
A higher FTP means you can ride faster and harder before dipping into your limited anaerobic reserves. It is the foundation upon which all endurance performance is built. The following sections will break down the key questions from the podcast to provide a comprehensive understanding of how to test, train, and apply this crucial metric.
The podcast tackles a common question: Should you train at Sweet Spot, Threshold, or VO2 Max to raise your FTP? The answer is not a simple “one is best,” but rather an understanding of how each type of training provides a different stimulus.
A. Direct Threshold Training (The Gold Standard)
The Method: Performing intervals at or very near your current FTP (95-105%). This includes classic workouts like 2x20 minutes at FTP or “over-unders” where you alternate between slightly below and slightly above FTP.
The Physiology: This is the most direct way to improve FTP because the training stimulus is perfectly specific. You are directly challenging the physiological systems that define your threshold:
Lactate Shuttling & Clearance: You force your body to become more efficient at clearing lactate from working muscles and using it as fuel in other muscles (like the heart and slow-twitch fibers).
Mitochondrial Respiration: You stimulate the growth and function of mitochondria, the “powerhouses” of your cells, enhancing your aerobic energy production.
Enzymatic Activity: You increase the concentration of key aerobic enzymes that facilitate energy production.
The Verdict: As the podcast states, for a targeted improvement in your FTP number, nothing is more effective than training at FTP.
B. Sweet Spot Training (The Volume Builder)
The Method: Sustained intervals at 88-94% of FTP.
The Misconception: Many athletes believe sweet spot is superior because it feels easier to recover from. The podcast correctly points out that if sweet spot work feels significantly easier than threshold work, your FTP is likely set too high.
The True Benefit: The real advantage of sweet spot is that it allows you to accumulate a greater total duration of high-quality aerobic work than you could at full threshold. The adaptive signal for your body is a combination of intensity and duration.
C. VO2 Max Training (Raising the Ceiling)
The Method: Short, very hard intervals (3-8 minutes) at an intensity well above FTP (106-120%).
The Physiology: VO2 max is your absolute aerobic ceiling—the maximum amount of oxygen your body can utilize. Your FTP is always a percentage of your VO2 max (for trained athletes, typically 78-88%).
The Relationship: For a trained athlete, doing VO2 max work does not directly “pull up” FTP. Instead, it raises the entire ceiling. Imagine your VO2 max is a room’s ceiling and your FTP is a balloon pressed against it. To get the balloon higher, you first need to raise the ceiling. After a block of VO2 max training, your absolute aerobic potential is higher, creating new room for your FTP to grow when you return to dedicated threshold training.
D. Aerobic Base Training (Extending Your Endurance)
The Method: Long, low-intensity rides (often called Zone 2).
The Effect: For most trained athletes, this type of riding doesn’t significantly increase the raw FTP number. Instead, it primarily increases your Time to Exhaustion (TTE)—the duration for which you can hold your FTP.
The Physiology: This happens because base training dramatically improves metabolic efficiency, particularly your ability to oxidize fat for fuel. By becoming better at using fat at high intensities, you spare precious muscle glycogen, allowing you to sustain your effort for much longer.
The answer is a nuanced “no, but also yes.”
The “No”: Maximal strength (e.g., a 1-rep max squat) has almost no direct correlation with FTP. FTP is an endurance ability limited by your cardiovascular system and cellular metabolism, not your ability to generate peak force for a single muscular contraction. As the podcast notes, a world-class powerlifter will not have a world-class FTP.
The “Yes”: Heavy lifting provides crucial neuromuscular adaptations.
It improves your ability to recruit a larger number of muscle fibers, including larger, more powerful motor units that are typically reserved for high-force efforts.
By being able to distribute the workload across a greater muscle mass, you reduce the metabolic strain on any individual fiber, thereby improving muscular endurance and efficiency. This neural benefit is a key reason why trained endurance athletes can access more of their muscle mass than untrained individuals.
How close does your FTP estimate need to be? The podcast suggests an acceptable error of 5-10 watts, with a strong preference for underestimating.
The Danger of Overestimation: This is the single worst mistake in setting training zones. If your FTP is set too high, every workout becomes harder than intended. “Threshold” intervals become VO2 max efforts, and “Sweet Spot” becomes Threshold. This leads to failed workouts, excessive fatigue, and a high risk of overtraining, ultimately halting progress.
Sources of Error:
Power Meters: Even the best power meters have an error margin of +/- 1-2%. A 2% error on a 300-watt FTP is 6 watts.
Testing Protocols: A ramp test, which is short and finishes with an all-out anaerobic effort, will almost always yield a higher FTP estimate than a true 60-minute effort. This is because it is heavily influenced by your anaerobic capacity, not just your aerobic engine.
The Takeaway: It is always better to lowball your FTP by a few watts and complete your workouts successfully than to overestimate and struggle.
Maintenance Load: To maintain your FTP during a period of reduced training or focus on another system (like VO2 max), one or two high-intensity sessions per week are generally sufficient. This could be a threshold workout (e.g., 3x15 min) or even a VO2 max session. The high aerobic stimulus is enough to prevent detraining.
Creating a New “Normal”: Making your peak FTP a more permanent baseline is not about just doing more FTP work. It is the result of a holistic improvement of your entire aerobic system. By building a larger aerobic base, raising your VO2 max ceiling, and improving your muscular endurance, you become a more robust athlete. This means that when you do detrain, you fall back to a much higher level than in previous years.
This question reveals two core principles of FTP adaptation:
The Need for Continuous Stress: For an interval to be effective at stimulating threshold adaptations, it must be long enough to prevent your cells from fully resetting to their resting state. The podcast suggests a minimum duration of around 10 minutes. This is why a workout like 60x1 minute at FTP with rests in between would be highly ineffective; the stress is never sustained long enough.
The Primacy of Total Duration: Once the minimum continuous interval length is met, the primary driver for overload becomes the total time accumulated at the target intensity.
Therefore, 5x15 minutes (75 min total) is a better workout than 4x15 minutes (60 min total), even if it requires slightly longer rest periods to accomplish.
Progressing from 2x20 minutes to 1x40 minutes is also a powerful stimulus, as it specifically challenges your ability to sustain the effort continuously.
This is perhaps the most important and misunderstood concept for many racers. The assumption that FTP is only for time trialists and climbers is fundamentally wrong.
FTP as Your Recovery Engine: Your aerobic system is what regenerates your anaerobic energy stores (phosphocreatine) between hard efforts. A higher FTP means a more powerful aerobic engine, which means you recover faster after a sprint, an attack, or a surge from the pack. The rider with the higher FTP can make more hard efforts and still be fresh for the finish.
FTP and Relative Intensity: Your FTP dictates the metabolic cost of every effort.
Scenario: The pack surges up a small rise at 400 watts.
Rider A (300W FTP): This is a massive anaerobic effort, costing them dearly.
Rider B (400W FTP): This is simply a threshold effort. They can handle it aerobically.
Result: Rider B arrives at the finish line with far more energy reserves for the final sprint.
The Mark Cavendish Example: The reason Mark Cavendish can use his world-class sprint at the end of a 5-hour race is that he has a world-class FTP that allows him to get to the finish without having emptied his tank just staying with the peloton.
Normalized Power: The normalized power for a hard road race or criterium is often very close to a rider’s FTP, demonstrating the immense underlying aerobic demand of these events, even if they are punctuated by anaerobic spikes. Your FTP is the price of admission to be able to contest the finish.