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I ran 2:42 at Sydney Marathon last year. The engine was there — VO2max, threshold pace, all of it pointed to a faster time.

But somewhere after 25K, the wheels came loose. A slow, frustrating fade I couldn't stop.

That fade has a name: durability failure. And it's the most common reason well-trained marathon runners underperform their fitness on race day.

In this video I break down exactly why it happened, where my fitness actually sits right now, and whether the data supports my 2:39 target at this year's Sydney Marathon — using a free tool called Runalyze that tracks two metrics most runners completely ignore.

Once you understand these two numbers, you'll know whether you need more fitness… or just better marathon-specific preparation.
You'll learn:
✅ Why your Garmin's marathon prediction is often way off
✅ What Effective VO2max actually measures — and why mine suggests 2:36
✅ Marathon Shape: the metric that explains why fit runners still fade late
✅ Why 2:42 to 2:39 isn't about being "three minutes fitter"
✅ The exact 3-phase training block structure I'm using to fix my durability
✅ How to use Runalyze for free to get an honest marathon prediction
✅ Why Marathon Shape — not VO2max — is the number that matters most on race day

We also cover:
• Why most runners chase more speed work when durability is the real problem
• How weekly mileage and long run distance combine to predict your marathon readiness
• Why the taper doesn't make you fitter — it just lets your fitness show up
• What sub-2:40 marathon running actually demands from your training

I'll also walk through my honest assessment of whether 2:39 is realistic — the gap that still needs to close, what has to go right, and how I'm tracking it week by week.

This isn't a generic marathon training guide. It's a data-backed look at one runner's real numbers, real gaps, and real plan — so you can apply the same framework to your own training.

💬 Drop a comment and tell me: — Your current marathon PB — Your next race goal — Your current weekly mileage and longest long run — Whether your fitness and your marathon shape actually match