Original episode & show notes | Raw transcript
This document provides a comprehensive explanation of the advanced training concepts discussed in the Empirical Cycling podcast episode concerning VO2 max and Functional Threshold Power (FTP). It is intended for an educated audience seeking a deep understanding of the principles and their practical applications.
VO2 max represents the maximum rate of oxygen your body can consume during intense exercise. Training to improve VO2 max is crucial because it acts as the physiological “ceiling” for your FTP. Raising this ceiling is a prerequisite for significant, long-term gains in sustainable power.
A “block” is a focused period of training, typically 2-3 weeks, dedicated to a specific physiological adaptation.
Why Block Training? The primary reason for isolating VO2 max training into a block is for variable control. It allows the coach and athlete to apply a specific, potent stimulus (high-intensity VO2 max intervals) and observe the expected outcome (an increase in VO2 max and, subsequently, FTP).
It’s Not the Only Way: The hosts emphasize that a dedicated block is a “middle ground approach” and not the only effective method. Its success is highly individual.
An athlete must be adequately prepared to handle the high stress of a VO2 max block and reap its benefits.
High Aerobic Base: The athlete should be at a good aerobic fitness level, ideally achieved through a significant volume of low-intensity training. Starting a high-intensity block from a de-trained state (“off the couch”) leads to excessive fatigue accumulation without optimal adaptation.
Extended Time to Exhaustion (TTE): Before starting a VO2 max block, it is highly beneficial for an athlete’s TTE at their current FTP to be well-developed, ideally in the range of 55-60 minutes or more. This indicates a robust aerobic foundation, setting the stage for a more significant FTP increase post-block.
If a dedicated VO2 max block is not yielding results, or if an athlete is struggling with motivation or quality, a “mixed block” is a viable alternative.
Structure: This involves performing both VO2 max and FTP/Threshold workouts within the same week (e.g., one VO2 max session and one or two threshold sessions).
Benefit: This approach provides a balanced stimulus and can be more manageable for some athletes, preventing the deep fatigue that can accumulate during a focused high-intensity block.
The quality and execution of the intervals are paramount.
Starting Effort: The common advice to “start hard” is nuanced.
It Depends: Athletes with high anaerobic capacity (good sprinters) should be cautious with hard starts, as they can exhaust themselves in the first interval, compromising the rest of the workout.
Pacing: It can be more effective to pace the effort evenly, aiming for the highest sustainable power for the entire duration (e.g., 3-5 minutes). Breathing should be very heavy for the majority of the interval.
Interval Duration: The podcast challenges the notion that you must do 5-minute intervals.
Flexibility: As fatigue accumulates throughout a block, it is effective to shorten the interval duration (e.g., from 5 minutes down to 2-3 minutes) while maintaining the total time at intensity (e.g., 15-20 minutes per workout).
Minimum Duration: A 2-minute interval is suggested as a practical minimum for steady-state efforts aimed at VO2 max adaptation.
High Cadence: While not absolutely mandatory, training at a high cadence (100-110 RPM) during VO2 max intervals is strongly recommended.
Physiological Rationale (The Muscle Pump): The primary driver of VO2 max adaptation is increasing the heart’s stroke volume. High cadence activates the “muscle pump” mechanism, where the rapid contraction and relaxation of leg muscles helps squeeze blood back to the heart. This increases venous return and diastolic filling pressure, which is thought to be a key stimulus for cardiac adaptation.
Practical Benefit: It reduces specific muscular fatigue in the legs, allowing the cardiovascular system to be the primary limiter. This can improve workout quality, especially during double-day training sessions.
This is the single most common area where athletes make mistakes.
Intra-Block Recovery: Two hard workouts per week is often sufficient to allow for adequate recovery and adaptation between sessions. Stacking workouts (e.g., Thursday-Friday-Saturday) followed by several recovery days can be an effective strategy.
Post-Block Recovery: The recovery after the block is crucial and often underestimated.
Delayed Adaptation: The full FTP improvements from a hard VO2 max block may not be realized for 2 to 8 weeks. Immediately jumping into an FTP block after only 3-4 days of rest is a common mistake that will blunt the potential gains.
Assessing Recovery: An initial 3-5 minute power test after a week of rest might show similar power to pre-block levels but with high residual fatigue. This does not mean the block failed. It means more recovery is needed. As the deep fatigue dissipates over the following weeks, the FTP will rise.
Functional Threshold Power (FTP) is the highest power a rider can maintain in a quasi-steady state for approximately 30-60 minutes.
This is a key, and sometimes counter-intuitive, concept.
The “Noob Gains” Phase: Early in a training career, almost any form of aerobic training, including FTP intervals, will raise FTP. This is primarily driven by an increase in plasma volume, which enhances cardiovascular efficiency and raises VO2 max.
The Plateau: For a well-trained athlete, simply doing more FTP intervals will primarily extend their Time to Exhaustion (TTE) at their current FTP. It makes them more durable and efficient at that power but does not necessarily raise the power number itself. To raise the FTP “ceiling,” one must first raise the VO2 max “ceiling.”
The hosts describe FTP work this way to illustrate that it shares many of the same aerobic adaptation pathways as lower-intensity endurance riding. While the feel is different, the underlying physiological goals (mitochondrial biogenesis, capillarization) are similar. The primary difference is the intensity and the corresponding fatigue.
Dedicated FTP blocks are not always necessary. Like VO2 max work, it can be integrated flexibly into a training plan, such as in a “mixed block” or by doing one FTP-focused workout per week.
This section synthesizes the core philosophies and practical advice from the Q&A portion of the podcast.
Accuracy of FTP: An individual’s FTP is not a single number but a range of ~10 watts. Training slightly below your tested FTP is often more productive, as it manages fatigue better without sacrificing adaptation.
Off-Season is for Rest: It is not only acceptable but beneficial to let your FTP drop during an off-season. This period of rest is essential for physical and mental recovery, setting the stage for future improvements. Trying to hold peak fitness year-round is a recipe for stagnation or burnout.
High VO2 Power vs. FTP: A large discrepancy between 5-minute power and FTP is common in riders with a high anaerobic capacity. It is not inherently “good” or “bad,” but rather a reflection of an individual’s physiological profile.
Dealing with Stagnation: If your FTP is no longer improving despite consistent training, especially on lower volume (sub-15 hours/week), it may be more productive to shift focus. Instead of chasing a higher FTP, work on other performance aspects:
Race craft and pack skills
Sprinting or repeated high-power efforts
Pacing and durability
Ensuring you are arriving at races fresh rather than fatigued from training overload.
The Importance of Self-Awareness (RPE): Throughout the discussion, the hosts return to the idea that athletes must be honest with themselves about how they feel. Rate of Perceived Exertion (RPE) is a critical tool. If a workout feels excessively hard, or if you are constantly on the edge of failure, you are likely accumulating too much fatigue, which will sabotage your long-term progress. It is better to finish a block feeling like you could have done a little more than to overshoot and require months to recover.