Original episode & show notes | Raw transcript
“Over-under” intervals are a form of cycling workout characterized by alternating periods of intensity over a specific metabolic threshold (like FTP) with periods of intensity just under that same threshold. A common example is alternating between 110% of FTP (the “over”) and 90% of FTP (the “under”) without any true rest periods in between.
This guide, based on the provided podcast transcript, explores the concepts surrounding these intervals in two main parts:
The Physiology and Theory: We will examine the commonly cited physiological benefits of over-unders—such as improved lactate shuttling and tolerance—and analyze the podcast’s critical perspective on whether these benefits are unique or superior to other forms of training.
Practical Application and Programming: We will detail the practical “rubber meets the road” approach to programming, progressing, and executing over-under workouts, including specific examples and alternative training methods for achieving similar goals.
The podcast begins by challenging the popular theoretical justifications for why over-unders are considered a superior form of training compared to traditional steady-state threshold work.
Purported Benefit
The Common Theory
The Podcast’s Counterargument
Better Lactate Shuttling/Clearance
By repeatedly producing high levels of lactate during the “overs” and then forcing the body to process it during the “unders,” the workout is thought to specifically upregulate MCT transporters and improve the body’s ability to “shuttle” and oxidize lactate.
This adaptation is not unique. All endurance training, particularly high-volume, lower-intensity work, increases mitochondrial mass, which is a primary driver of lactate oxidation. Threshold work and even VO2 max intervals also stimulate these pathways. There is no direct scientific evidence showing over-unders are superior to these other methods for this specific adaptation.
Improved Lactate Tolerance
The repeated exposure to the metabolic byproducts associated with high-intensity work (acidosis, etc.) during the “overs” is believed to improve the body’s tolerance to these fatiguing conditions.
“Lactate tolerance” is poor nomenclature. The goal is to improve anaerobic capacity and the ability to handle the metabolic environment created during maximal efforts. While over-unders contribute to this, workouts specifically designed to exhaust the anaerobic system (e.g., repeated short, maximal efforts) are far more potent for this adaptation.
The central conclusion from the physiological discussion is that while over-unders are an effective workout, their proposed benefits are not physiologically unique. The adaptations they stimulate are also achieved through a well-rounded endurance training program that includes high volume, steady-state threshold work, and anaerobic capacity training.
Despite the critique of their theoretical “specialness,” the podcast strongly endorses over-unders as a valuable and practical training tool. The focus shifts from why they might work in theory to how to make them work in practice.
The single most important rule for programming threshold-style over-unders is that the efforts must be sustainable. The goal is to accumulate time at a high, but manageable, metabolic load.
The “Overs” should be challenging but repeatable.
The “Unders” should be high enough to maintain stress but allow for enough recovery to complete the next “over.”
Failing an interval and having to pedal at a very low intensity for the remainder provides a significantly worse training stimulus than completing the full duration. More time at the intended intensity is always better.
For an athlete new to over-unders, the podcast recommends starting with a simple, feel-based workout to learn pacing.
Workout Example:
Base: 20 minutes at Sweet Spot intensity (approx. 88-94% of FTP).
“Overs”: Every 5 minutes, perform a 10-second acceleration. This is not a maximal sprint, but a controlled “push.”
Progression: Start with a conservative duration (e.g., 2-4 x 15 minutes) and gradually increase the total interval time (e.g., 3x20, then 3x25 minutes).
This approach serves two purposes:
It teaches pacing: The athlete learns how hard they can push and still recover. Going “full send” on the first acceleration results in a rapid and educational failure.
It mimics racing: It develops the specific skill of accelerating and then settling back into a hard, steady pace—a crucial ability for road racing, criteriums, and gravel.
Once an athlete has a feel for the effort, more structured intervals can be introduced. The podcast’s preferred structure for sweet spot/threshold work is a 1:4 over-to-under ratio.
Workout Examples:
Option A: 30 seconds “over” / 2 minutes “under.”
Option B: 1 minute “over” / 4 minutes “under.”
Intensity:
“Overs”: A general guideline is 20-50 watts over FTP, but the podcast emphasizes a “vibes-based” approach where the athlete rides to a feeling of “hard but sustainable.”
“Unders”: Sweet Spot intensity.
Progression: The primary method of progression is increasing the total time of the intervals. If you can complete 3x20 minutes, the next step is to aim for a longer duration, such as 2x30 minutes. If you cannot progress the duration, it indicates the intensity is too high, you are fatigued, or under-fueled.
Over-unders are highly adaptable. Key variables can be manipulated to target specific race demands:
Cadence: High-cadence “overs” (e.g., 110-140 RPM) are excellent for track cyclists and criterium racers to develop leg speed and neuromuscular coordination under load.
Starting on an “Over”: Beginning an interval with a maximal acceleration simulates the high-power starts of cyclocross, cross-country mountain biking, and aggressive gravel races.
Terrain: Using short, rolling hills for the “overs” and flats for the “unders” creates a dynamic, race-like workout.
If the goal is to target the specific physiological adaptations often attributed to over-unders, the podcast suggests other, potentially more direct, methods.
The most effective way to improve the body’s ability to oxidize lactate is to increase mitochondrial mass.
The Best Workout: A long endurance ride (e.g., 4-6 hours). High volume is the most powerful stimulus for building mitochondria.
Other Effective Workouts:
Threshold Intervals: Steady-state threshold work is described as “spicy endurance work” that provides a potent aerobic stimulus.
VO2 Max Intervals: Increasing your maximal oxygen uptake (VO2 max) directly raises your aerobic ceiling and, consequently, your lactate threshold.
To improve the ability to tolerate the metabolic byproducts of anaerobic efforts, you must perform efforts that maximally stress that system.
The Workout: Short, repeated maximal-effort intervals with incomplete recovery, performed until exhaustion.
Examples: 15 seconds on / 15 seconds off (15-15s), or 30s on / 30s off (30-30s).
Duration: Typically done in blocks of 5-8 minutes.
The Feeling of “Doing It Right”: The workout is defined by a feeling of profound muscular fatigue where the legs can barely contract, followed by systemic distress. The power output will drop dramatically over the course of the interval (e.g., from 1000 watts on the first rep to 400 watts on the last). This is a sign that the anaerobic system has been fully taxed.
The overarching message of the podcast is to adopt an empirical, results-driven approach to training.
Theory vs. Reality: While physiological theories are interesting, they should not dictate training choices if the practical evidence doesn’t support them. Over-unders are effective not because of a unique lactate-clearing mechanism, but because they represent a high-quality, sustainable aerobic workout that can be tailored to specific needs.
The Importance of a Feedback Loop: The ultimate test of any workout is whether it makes you faster. If you incorporate over-unders and see your threshold power increase and race performance improve, then they are working for you. If not, another approach may be better.
Mental Variation is a Valid Goal: Over-unders are an excellent tool for breaking up the monotony of repeated steady-state intervals, which is a valid and important reason to include them in a training plan.