Train Closer to VO₂max, Gain More: What the Research Tells Us About Interval Training

How hard should you push during intervals to improve cycling performance?

A study by Rønnestad and colleagues has a clear answer: the closer your training intensity is to your VO₂max, the greater the improvement.

Let’s break down what the study found—and how you can apply it to your own sessions.

European Journal of Sport Science - 2024 - Odden - The higher the fraction of maximal oxyg.

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The VO₂max Study at a Glance

The research involved 30 well-trained cyclists, all with solid aerobic conditioning. The training plan lasted 10 weeks, and every athlete completed the same number of interval sessions.

The cyclists were split into two groups:

• HIGH group: Trained intervals at ~90% of their VO₂max power output.

• MOD group: Trained intervals at ~70% of their VO₂max power output.

Both groups did three interval sessions per week. Each session consisted of 5 x 5-minute intervals, with 2.5-minute recoveries between efforts.

The only variable? How close each athlete worked to their VO₂max power.

Testing Protocols Used

To assess performance changes, the following tests were performed:

• Incremental VO₂max test: Conducted on a cycle ergometer to determine each cyclist’s aerobic capacity.

• 20-minute and 40-minute time trials: Used to measure real-world performance gains.

• Time spent at ≥90% VO₂max: Calculated during each session using indirect calorimetry.

These tests were repeated before and after the 10-week intervention.

What the Researchers Found

The results were clear:

• HIGH group increased 40-minute time trial power by 10.1%.

• MOD group improved by only 4.1%.

• HIGH group also had a higher increase in VO₂max (measured in ml/kg/min).

• During training, the HIGH group spent nearly twice as much time at or above 90% of VO₂max.

These changes occurred without increasing weekly training volume.

What changed was training density at the right physiological target.

Why It Matters

This study supports what many top coaches already believe: Time near VO₂max is a powerful stimulus for endurance performance.

When intervals are long enough, and recovery short enough, oxygen uptake stays elevated. That strain is what drives aerobic adaptation.

So while both groups completed the same number of sessions, only one spent meaningful time at a level high enough to spark major gains.

How to Apply This in Your Own Training

Multiple linear regression of the average fraction of maximal oxygen uptake (82% of V̇O_2max) elicited during the intervals related to changes in (A) maximal 1-min incremental power output during the V̇O_2max test (W_max.

Want to get more from your intervals? Adjust how you train, not just how often.

Try these evidence-backed approaches:

• Use 4–6 minute intervals at 90–95% of your VO₂max power or HR.

• Keep recoveries short (2–3 minutes max) to maintain high oxygen demand.

• Include 30/15s or 40/20s for athletes who struggle to hold high intensity for long durations.

• Monitor with heart rate, RPE, or power—aim for zones that push your breathing rate and fatigue.

• Log how much time you actually spend near your ceiling, not just how hard the effort felt.

Small tweaks can unlock bigger returns.

One Caution

VO₂max intervals aren’t for every day. They’re high stress and need proper recovery.

Use 1–2 sessions per week during performance-focused phases. Pair with easy endurance rides or low-intensity strength work.

Quality, not quantity, wins here.

Final Thought

Training closer to your VO₂max isn’t about chasing pain. It’s about precision.

This study reminds us that effort is a tool. Used well, it leads to real, measurable progress.

So ask yourself:

Are your intervals giving you time at VO₂max—or just time spent tired?