Building VO2 Max: The 30/30 Protocol Explained

Indoor Training, Turbo Training

If you’ve ever wondered why your training partner can hold the same wheels for three hours that you can hold for one, the answer is usually some combination of two numbers: their threshold and their VO2 max. 

Threshold gets most of the column inches because riders can measure it themselves via functional threshold power (FTP) tests, 20-minute efforts, ramp tests and so on. 

VO2 max gets less attention because it’s harder to measure outside a lab and because for years it was treated as a fixed ceiling that you were born with.

That second idea turns out to be only partly true. Yes, genetics set a range. But within that range (and the range is wider than most riders realise) VO2 max responds beautifully to training. 

And one type of training in particular.

What is VO2 max?

As you’ll learn during cycle coaching sessions, VO2 max is the maximum volume of oxygen your body can take in, transport and use per minute, normalised to your bodyweight. 

It’s measured in millilitres per kilogram per minute (ml/kg/min). A sedentary 40-year-old man might sit around 35. A reasonably fit amateur cyclist might hit 50. A national-level rider, 65–70. 

Pogačar’s reported figure is north of 89.

Two systems determine your VO2 max. 

The first is central: How much oxygenated blood your heart can pump per minute (cardiac output), which is a function of how much blood it ejects per beat (stroke volume) and how many beats per minute it manages at maximum effort. 

The second is peripheral: How effectively your working muscles extract that oxygen, a function of capillary density, mitochondrial content and the activity of the enzymes that handle aerobic metabolism.

The classic Fick equation captures it: VO2 max = cardiac output x (a-vO₂ difference). 

In other words, your ceiling is set by how much oxygen you can deliver and how much you can use.

Why threshold isn’t enough

Plenty of strong amateur cyclists have a high FTP relative to their VO2 max. They sit at 88–92% of VO2 max at threshold. They’re efficient, but they’ve nowhere left to go. 

To raise the threshold further, they need to raise the ceiling above it.

This is why coaches push VO2 max blocks in the spring, after the base is built. You can’t keep adding floors to a building without raising the roof.

How long should VO2 intervals be?

For 30 years, the orthodoxy was that VO2 max was best developed through four to eight-minute efforts at maximal sustainable intensity: Tabata Plus, Billat 30/30 at VO2 max, or simply 5x5min at 110% FTP. 

They work. They’re also brutal and they don’t accumulate as much time near VO2 max as you might think. Most of each interval is spent climbing towards it.

Then in 2015 Bent Rønnestad’s lab at Lillehammer University College published the work that changed practice. 

They compared traditional long intervals (4×5 min) against short intervals (three sets of 13x30s hard/15s easy) over a ten-week block in trained cyclists. 

The short-interval group accumulated significantly more time at >90% of VO2 max per session, improved VO2 max by ~8.7% vs ~3.6% for the long-interval group, reported lower session rate of perceived exertion (RPE), and improved 40-minute time-trial power by a meaningful margin.

The mechanism is simple. 

After the first 30-second burst, your oxygen consumption is already elevated. The 15-second easy doesn’t bring it down to baseline, it just stops you from accumulating local fatigue. 

The next 30 seconds picks up where the last left off and so VO2 climbs and stays high for almost the whole set.

The Rowe & King 30/30 session

Here’s the version we prescribe to most R&K clients in Week 1 of a VO2 max block. 

Adjust the rest based on how the first set goes. If you can’t complete Set 3 at the same average power, the rest is too short for you right now.

Warm-up: 

15 min progressive build, finishing with 3x30s openers at ~140% FTP, 90s easy between.

Main set (3 sets): 

  • 13×30 seconds at maximal effort you can repeat (typically 120–140% of FTP for trained riders) / 15 seconds easy soft-pedalling.
  • The goal is not to hit a number on the first rep. It’s to hold a consistent number across all 13.
  • 4 minutes of easy spinning between sets.

Cool-down: 

10 min easy.

Total time: 

~55 minutes. Total hard time: ~20 minutes. Time near VO2 max: Typically 12–16 minutes if you pace correctly.

How to pace it properly

The single most common mistake on this session is going too hard in the first three reps and dying through reps 9–13. T

he aim is the opposite: even or slightly progressive power across all 13 reps and all 3 sets.

  • Set 1 should feel hard but controlled. RPE 8/10.
  • Set 2 should feel like a slog. RPE 9/10.
  • Set 3 should feel borderline impossible. RPE 9.5/10.
  • If set 1 already feels 9.5/10, you’re going too hard. Drop the target power by 20–30W.

How often should you train VO2 max?

A VO2 max block is typically three to four weeks long, with two VO2 max sessions per week (Tuesday and Saturday, or Wednesday and Sunday, separated by 72 hours where possible). 

Sandwich the block between a base block and a threshold/race-prep block. Don’t try to run VO2 max work year-round, as adaptations plateau and accumulated fatigue starts to dominate.

For time-crunched riders training six to eight hours per week, VO2 max work delivers an outsized return on investment. 

You can meaningfully lift fitness with two 50-minute sessions per week, where the same hours of Zone 2 wouldn’t budge the needle.

A note on heart rate

Don’t pace this off heart rate. Heart rate lags badly behind effort on intervals this short. By the time it’s climbed to where you’d expect, the interval is over. 

Pace off power, or off RPE if you’re not on power.

The bottom line

VO2 max is the ceiling that every other zone sits beneath. Lifting it is the highest-leverage move you can make once your base is solid. 

And the most time-efficient way to lift it is the one that, on paper, looks too easy: 30 seconds hard, 15 seconds off, repeated until you can no longer hold the number.

This is the second article in our Build a Better Engine series. 

Next week: Threshold… what FTP actually represents, why the sweet spot works, and the 2×20 session that built half the peloton.

Coached by Rowe & King: Built for you.