“Be Strong on the Marathon”

Fall marathon season is rolling in—perfect timing to revisit two limiting beliefs:

• Marathon performance is purely about endurance, and

• The “wall” is inevitable because of glycogen depletion.

This week, we’re cracking those dogmas to free you from the myth of the inescapable wall.

Have you ever felt that moment when your stride seems to stick to the pavement? The “wall” isn’t just about glycogen. It’s first and foremost the moment when you no longer have enough useful strength to rebound quickly, cleanly, and almost “for free.” What if running economy were, at its core, a question of available power?

Running is fleeing and predating (and that changes everything)

Human running evolved to escape and pursue. It alternates propulsion and suspension: in the air, you apply no force to the ground; on contact, everything happens in a few hundredths of a second. The secret? Being able to push off fast enough to take off and maintain momentum (impulse ≈ Δp, where p = m·v). When impulse fades, mechanics seize up—and energy cost climbs.

Yes, running “costs” more than walking

A simple order of magnitude: ~1 kcal/km when running vs ~0.5 kcal/km when walking. Why? Because of the suspension phase and the need for an effective rebound. If the leg–tendon unit isn’t “strung like a bow” at landing, energy doesn’t transfer smoothly: you land heavy, lose spring, and must re-inject more energy at each step.

Under fatigue: the trap of “I’ll just increase cadence”

We tell ourselves: v = step frequency × stride length, I’ll spin the legs faster. Except that moving the lower limbs is costly (rotational energy). The backward sweep is energy-hungry, and propulsion is the most force-dependent phase. If strength drops (glycogen low), ground contact time lengthens, elastic return falls, and energy cost can spike (> 20%). In short: economy comes from power, not from fiddling with cadence.

“Useful” variability beats the myth of a perfectly steady pace

The best marathons are not perfectly flat pace lines—they show smart oscillations in speed. In our analyses, high performers allow small, asymmetric fluctuations that help them fine-tune energy systems, recover, and avoid cardio/VO₂ drift. (See the study on pace oscillations and performance.) [Billat et al., “Marathon performance & oscillations.”]

Humans can self-regulate acceleration (for a long time)

Another key point: we can maintain self-paced accelerations (gentle, moderate, hard) up to exhaustion thanks to small stochastic corrections around an average value. Modeled with an Ornstein–Uhlenbeck process, these accelerations remain remarkably stable despite fatigue. This is strong scientific support for acceleration-based training by feel, rather than rigid, square-wave intervals.
[Billat et al., “Humans are able to self-paced constant running acceleration until exhaustion”; “Long-term constant acceleration sustained via stochastic short-term corrections.”]

What this changes for training (spoiler: strength is specific)

No need to bet everything on heavy squats. Marathon-useful strength is specific: fast, elastic, with contraction angles and speeds close to running (force–velocity and tension–length). Prefer building elastic-functional strength and the ability to accelerate cleanly (short vertical time + tonic propulsion) to protect rebound when glycogen dips.

Experimental evidence (and not only in humans!)

In older mice, a short acceleration-based training model outperformed a long endurance protocol: higher max speed, longer time to exhaustion, and better mitochondrial/enzymatic markers (CS, LDH, CK). Practical takeaway: short, well-measured accelerations can revive both the aerobic–anaerobic “powerhouse” and muscular “grip.”
[Billat et al., “A new model of short acceleration-based training.”]
To calibrate effort precisely, a low-acceleration ramp protocol (0° slope) proved optimal to elicit true VO₂max in animals.
[Ayachi et al., “Validation of a Ramp Running Protocol.”]

Signature Session — HIIT by Acceleration (not square waves)

Why? Because F = m·a. Training acceleration means training impulse (force × ground-contact time), the thing that makes your stride lift off—without breaking your mechanics.

Format (40–50′)

• Warm-up 20–25′ + 2–3 progressive strides.

• Block A: 8 × 15–20″ progressive acceleration (from tonic → strong), 40–60″ easy jog recovery.

• Block B: 6 × 10″ on a gentle hill (focus on vertical rebound), 50–60″ recovery.

• Option: 4–6 technical tendon strides (80–100 m).

• Cool down 10–15′.

Technical pointers

• Short contact (“hot touch”).

• Tonic vertical push (rebound, no dragging).

• Active arms (sync the impulse).

• Shortened backward sweep (don’t let the leg trail).

Race Day: why strength gets you past the wall

• A reserve of power protects your rebound when glycogen falls.

• Contact time stays short, so economy stabilizes.

• Useful variability (micro-adjustments in cadence/stride length) prevents mechanical saturation.

Teaser — What’s next

How to subtly vary speed throughout the marathon to alternate energy systems, avoid saturation (cadence, amplitude), and optimize economy via controlled cadence changes—a “black” that isn’t monochrome, in the spirit of Pierre Soulages’ Outrenoirs.

References (selection)

1. Billat V. et al. — Marathon performance & oscillations (analysis of rhythm oscillations and performance).

2. Billat V. et al. — Humans are able to self-paced constant running acceleration until exhaustion.

3. Billat V. et al. — Long-term constant acceleration can be sustained freely in running via stochastic short-term corrections.

4. Niel R., Billat V. et al. — A new model of short acceleration-based training.

5. Ayachi M., Billat V. et al. — Validation of a Ramp Running Protocol.

see all publications:

https://publications.billatraining.com/