Ready for the marathon? These are the 5 markers I check. 🏅

Fri Aug 1 · 🇺🇸

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Friday August 1 · Coaching note

Every season I get the same message: “Henri, I already ran a 10K and a half marathon, can I sign up for the Chicago marathon?”

The answer is rarely a simple yes or no. The marathon does not forgive impatience — it is not a doubled half marathon. It is 42.2 km with physiological, metabolic and cardiac demands that require a specific foundation.

Here are the 5 markers I review with every athlete before giving the green light.

① Sub-2:00 half marathon — repeated, not just once

A single result can be a good day. What I look for is 2–3 sub-2:00 halves over 6–12 months, in different conditions. The half already demands energy management, sustained thermoregulation and eccentric muscle endurance — everything that gets amplified, not just doubled, in the marathon. (PMID:32421886)

💡 A ceiling touched by accident vs a solid floor to build from — that is the difference.

② Sustained weekly volume for 8–12 weeks

I do not trust one week of 60 km followed by three weeks of 30 km. The evidence is clear: both total volume and the longest long run associate independently with injury risk when increased abruptly. (PMID:32421886)

💡 Minimum 40–50 km per week sustained before starting a marathon block. No jumps over 10% week to week.

③ Long runs of 25–30 km without post-run collapse

It is not just about completing the distance — it is about how the body responds in the 2–3 days after. Functional recovery in 48–72 hours (sleep, appetite, gait, mood) is a reasonable proxy of real physiological stress. (PMID:41922043)

💡 If you need a week to feel normal after 28 km, the system does not yet tolerate that volume of eccentric muscle damage.

④ Cardiovascular health evaluated — especially masters

Prolonged endurance exercise is not physiologically neutral for the heart. Research documents structural and functional cardiac changes with relevant differences between age groups. (PMID:40667749) For athletes over 40 without a recent long-race history, I request a basic cardiovascular evaluation.

💡 Not fear — prudence. The same standard I apply to myself competing in masters 45–49.

⑤ Thermoregulation tested in real conditions

The marathon exposes the body to hours of sustained metabolic heat generation. Temperature, humidity, body composition and acclimatization interact to determine the risk of hyperthermia. (PMID:11547895)

💡 If you have only run long distances in cool climates, you have not tested a critical component of race day.

Henri perspective

These markers are not a wall — they are a map. If you do not meet one yet, you know exactly what to work on before the start line. The marathon is won in the months of preparation, not on race day.

📖 Full article — 9 min read · 5 studies with PMID

The blog includes why I reject the “5 years of running” rule for lacking peer-reviewed evidence, and how to apply these markers to your specific case.

🇺🇸 Read full article → 🇪🇸 Leer en Español →