Stop Chasing the Secret Session
Scroll far enough through endurance training content and you'll meet the same promise, dressed up in different clothes: a named interval protocol, a scientific citation, and the quiet implication that this is the one combination of work and rest that finally unlocks your engine.
Here's the reframe. Next time someone hands you the one session that's meant to lift your VO2max by some headline number, pause and ask: did they really find something magical?
They didn't. Because whatever the work-to-rest ratio, whatever study sits behind it, every one of those protocols is built from the same three ingredients: intensity, duration and frequency (Seiler, 2010). Combine them in the right proportions and you send the body a signal to get better at transporting and using oxygen — the machinery behind aerobic performance. The names change. The physiology behind them doesn't.
Science matters — and it has limits
None of this is a knock on the research. Science is how we know those three levers matter at all, and it deserves real respect. But endurance science comes with genuine limits, and reading it honestly means holding both truths at once.
Some questions are simply hard to study well. Study designs vary widely, sample sizes are often small, and the people in them tend to be very specific — highly trained athletes, or a handful of physically active students. A finding from a narrow sample transfers cleanly to that sample, and rarely to everyone else. Different physiology means a different signal, and a different response. What lit one group up may do very little for you.
What a small sample really tells you
The most widely shared protocol in this space is a good example of exactly this. The original study behind it ran on a handful of young, physically active men, on a stationary bike, working at a very high intensity, several times a week for a matter of weeks. There's little detail on their broader training history.
So the honest claim the study supports is narrow: this protocol improved a specific marker in a small group of young, active men, on a bike. Not "this protocol will boost your VO2max" — full stop.
A sample that small cuts both ways. An effect seen in a handful of people doesn't guarantee the same effect across the wider population they came from, and it certainly doesn't guarantee it in a 45-year-old triathlete training around a full-time job, three disciplines, and a stiff lower back. Small samples raise the risk of false positives and false negatives alike. One striking result is a starting point for more research — not a prescription for everyone who reads about it.
So what actually makes a session work?
Not its name. Its fit.
A session has to fit the athlete — their training history, their physiology, their current limiters — and it has to serve a clear purpose connected to the goal being trained for. A protocol lifted off a graphic satisfies neither of those on its own. The rest comes from doing the work, honestly, over time.
- Fit — the session matches the athlete's history, physiology and current limiters, and connects to a clear training goal.
- Repetition — running the same session week after week is what teaches pacing, and how much of it the body can actually absorb. Novelty works against that learning.
- Training quality — the point that ties it all together: execution has to match intent. A well-designed VO2max session run at the wrong intensity is just a hard day with no address on it.
- Standardisation — repeatable sessions and repeatable tests are what let you see whether any of it is actually working. Run a different benchmark every time, and you're only guessing.
The infographic isn't wrong, exactly. Those protocols are all real and well studied. But the chart is the menu, not the meal. The skill isn't collecting sessions — it's choosing the right lever, for the right athlete, at the right time, and executing it well enough that the body gets the message.
Stop chasing the secret session. There isn't one. There's just intensity, duration and frequency — and the discipline to apply them with purpose.
Stay reflective. Train smarter. Race faster.