If you’re looking for one session that can rapidly lift your top-end aerobic VO₂ max power, the 30/15 protocol sits right near the top.
The structure is simple: 30 seconds hard, 15 seconds controlled.
Repeat.
At the Road Cycling Academy, we consider this protocol one of the best – if not the best – ways to boost VO₂ max.
Now, that’s a big claim. So here’s the context…
One of RCA’s coaches, Ben Treble, recently travelled to Europe to complete his Level 3 UCI coaching accreditation. While there, he attended presentations from leading researchers in endurance performance including Brent Rønnestad, one of the key authors behind many VO₂ max training research papers.
Brent suggested in one of his lectures that – based on the research he’s conducted and reviewed in the VO₂ max space – the 30:15 protocol consistently produces some of the strongest outcomes.
That does not mean you throw out every other VO₂ max session. But if you had to choose one format that consistently delivers, this would sit extremely high on the list.
The problem? Most riders execute it incorrectly. In fact, stacking intensity without structure is one of the most common cycling training mistakes I see.
So let’s break down how to do it properly.
Step One: How to Execute the 30/15 Efforts (Where Most People Go Wrong)
Execution is everything. Most mistakes happen right here.
Always Start With a Good Warm-Up
Start with a 10 to 15 minute warm-up. On the trainer, I typically begin with 10 minutes of low Zone 2 spin, then a 3-minute ramp from below threshold to over threshold, followed by a few minutes of recovery spin before the first set.
For reference, my FTP in the video is approximately 340 watts. During that ramp, I gradually build from sub-threshold toward and slightly above that number before coming back to recovery.
I never skip this. It primes oxygen delivery and prepares you neurologically for maximal work.
Where Most People Go Wrong: The 30-Second Effort
Where most people get this workout wrong is the 30-second period. They are simply not going hard enough.
According to the research, to get optimal VO₂ max gains, you need to do this 30-second effort at your maximal VO₂ max output. Not just “hard.” Not controlled. Maximal for that duration.
If you undercook the 30 seconds, you blunt the entire purpose of the workout.
According to published research examining short-interval VO₂ max protocols, repeated 30/15 efforts performed at maximal aerobic power can produce significant improvements in oxygen uptake and high-intensity performance when executed correctly.
This reinforces why execution matters. The benefit is not in simply working hard. It is in hitting the correct power targets and maintaining pressure during the recovery phase.
So the Big Question You’ve Got to Ask Yourself?
What Is Maximal VO₂ Max Power?
Assuming you’re not going to jump into a lab and get hooked up to a ventilator, here are three simple options for you:
Option 1: Check Your 5-Minute Power Personal Best
Go to Strava or your training software (we use TrainingPeaks at RCA) and check out your power curve at 5 minutes for the year. What’s your personal best for 5 minutes?
For example, mine is 450 watts, giving me a clear target for the 30 second ‘on’ period.
If you haven’t completed a big 5 minute effort in recent times?
Option 2: Do a 5-Minute Test (best outdoors)
If you’re not confident in the 5 minute number you see on your Strava or your Training software – or you’ve lost a fair bit of fitness recently – find a local segment that’s 5 minutes in length and go all out and see what you can do. Although, attempt to find a safe area outdoors to complete this test VS indoors. Reason being, 5 minutes all out on the indoor trainer is rather grim.
Then take that power average for the 5 mins and that’s your target for the 30sec ‘on’.
Option 3: Use 120-130% of Your FTP
If you’re not able or willing to do option two, most of you will know what your FTP is. Take somewhere between 120 to 130% of that number, which tends to be where most people’s maximal VO₂ max power sits.
With a massive caveat, make sure your FTP is not over-inflated.
Personally, my best 5-minute power in 2025 was 450 watts. However, fitness fluctuates. So rather than chasing an outdated personal best, I selected 425 watts based on my current condition and training load.
Thankfully, at 15 years deep into structured training, I can make these assumptions and they’re fairly accurate. So if you’re also well in tune with your body; you can also make a guestimate here. However, just be sure that you’re feeling a rate of perceived exertion of close to a 9 during the workout.
The 15-Second Recovery: Not a Soft Spin
The research indicates you should return to roughly 50% of your maximal VO₂ Max output during the 15-second recovery period. This is another area many riders get wrong, as they drop to a very easy spin, which goes against the research.
In the example shown (in the video), 50% of 425 watts equals 215 watts. That sits in my Zone 2 power not Zone 1 recovery.
The goal isn’t to coast. It’s to maintain enough pressure to keep oxygen kinetics elevated while still allowing partial recovery before the next 30-second effort.
The idea here is we’re keeping you in that VO₂ Max state for the entire set, almost tricking the body during the 15sec off period that you’re still at VO₂ Max.
Step Two: Targeted Sets and Reps (& How to Progress)
Once execution is clear, you need structure.
At RCA, for a conditioned rider, we would typically program this workout as 3 sets of 12 reps of 30/15 efforts at maximal VO₂ max power, with 3 to 5 minutes rest between sets.
Between-set recovery should be Zone 1 spin at 40-50% of FTP. If you need more time while learning the workout, take 6-8 minutes. Quality matters more than hitting exact rest periods.
Start Conservative & Build Confidence
If you’re brand new to this style of workout, there’s nothing wrong with starting below your VO₂ max power (around 120% FTP) and aim for 6-9 reps initially. While research suggests you need to be at maximum VO₂ power – at around 9 reps to reach a true VO₂ max state, within the set – getting a good feel for the workout and building confidence should be your priority upfront.
If you’re failing at 6 or 7 on your first attempt, stop there. You’d rather complete the workout safely. Then you will know for the next attempt to adjust your power (lower) so you can achieve 9 without failing.
Build confidence first, then chase max effort.
Progress One Lever at a Time
Once you’re comfortable with the workout format and have built confidence over 2-3 attempts, gradually increase power toward maximal output. Then increase reps from 9 to 10 to 11 to 12 over weeks or months. Another option is reducing recovery from 5 minutes down to 3-4 minutes (3 minutes is the research-backed minimum).
Do not adjust all levers at once. Progress one variable at a time.
Block Structure: 6-8 Weeks Maximum
These intervals are powerful and fast-acting. You’ll see gains quickly, especially if you’ve built a strong aerobic base prior. But they’re fatiguing, especially if you’re doing these week in week out.
Therefore, assuming you have built a robust aerobic foundation, run this once per week for 6-8 weeks, progressing difficulty gradually. As a priority please include an easier week / deload week within the block, ideally 3-4 weeks in.
Done correctly, this should produce some epic gains.
Want to Increase Your FTP Without Guessing?
If you are serious about improving your VO₂ max and lifting your FTP, the next question isn’t just how hard to train, it’s what you should focus on right now.
Take our short 3-minute training quiz and we’ll help point you in the right direction based on your goals and current fitness.
👉 Take the 3-minute quiz here: RCA Cycling Training Quiz
Step Three: When and How Often to Use 30/15 Intervals
Before adding this session, ask yourself three questions:
- Have you built base fitness through consistent Zone 2 training?
- Have you spent a training block around threshold? (Sub-threshold and threshold HIIT)
- Do you have a reason to build top-end fitness right now?
If yes to all three, you’re ready to incorporate this once per week. This training is fast-acting but carries high metabolic and neurological cost, it must be respected.
How to Schedule VO₂ Max Intervals in Your Week
This session replaces another high-intensity session. It does not stack on top of one.
Guidelines:
- Once per week during a 6 to 8 week block
- Replace one HIIT session you’re already doing
- Never schedule back-to-back intensity days
- Pair with either Zone 2 or recovery days before and after
Example structure:
- Monday: Zone 2 ride
- Tuesday: VO₂ max 30/15 intervals
- Wednesday: Recovery or Zone 2 ride
- Thursday: Threshold session or bunch ride
- Weekend: Longer aerobic ride and/or group ride
You want to protect the quality of the session. If you’re unsure how to layer this into your plan, revisit how to structure a cycling training week before adding VO₂ max work.
Frequently Asked Questions About VO₂ Max Cycling Intervals
What Are the Best VO₂ Max Intervals for Cycling?
30/15 intervals are one of the most effective formats because they allow repeated exposure to maximal VO₂ power without the psychological burden of long sustained efforts like 3 to 5 minute blocks.
How Often Should You Do VO₂ Max Intervals?
For most cyclists, once per week during a focused 6 to 8 week block is sufficient. More is not better recovery and spacing matter.
What Is a Good VO₂ Max for Cycling?
It depends on age, sex, and training history. Rather than chasing a lab number, focus on improving your power at VO₂ max through structured training like the 30/15 protocol. But if you’re really after a number, 35–50+ mL/kg/min is good for healthy, active adults. Anything 50+ and you’re looking pretty solid compared the general population.
Does Cycling Increase VO₂ Max?
Yes, particularly when high-intensity intervals like 30/15s are layered on top of a strong aerobic base. But you need the foundation first.
Can Beginners Do 30/15 VO₂ Intervals?
Yes, but they should start conservatively at 90 to 95% of target power and build reps gradually before progressing toward maximal output. Build confidence first, then intensity.
Should I Do 30/15 Intervals on the Trainer or Outside?
Both work. The trainer gives you precise control over power output, which is ideal when you’re learning the workout. Outside works if you have a consistent climb or segment where you can maintain target power.
If you’d prefer this programmed properly within a structured progression rather than guessing at placement or load you can explore our custom 12-week cycling plan designed around your current fitness, goals, and training history.
Why the 30/15 Protocol Works (And How to Get It Right)
When executed correctly, VO₂ max cycling intervals using the 30/15 protocol are:
- Simple in structure
- Demanding in execution
- Fast-acting
- Highly effective
But you must:
- Hit true maximal power in the 30 seconds (not just “hard”)
- Maintain around 50% output in the 15 seconds (not soft spinning)
- Progress gradually (build confidence before chasing max)
- Place the session correctly within the week (once per week)
- Use it at the right point in the season (after building base and threshold fitness)
Get those details right, and the 30/15 protocol becomes one of the most powerful tools for lifting your top-end aerobic performance.
How RCA Can Help You Implement 30/15 Training Properly
The 30/15 protocol is powerful, but like any high-intensity method, it needs to be placed correctly within your broader training structure.
If you want it programmed at the right time, with the right progression and recovery spacing, that’s where structured coaching matters.
Our custom 12-week plan is designed to build this properly around your current level and performance targets. You can explore the RCA 12 Week Custom Plan here.
Train with structure. Progress with intention.