Vietnam Mountain Marathon 70K

Terrain style. Technical single-track, slick clay, steep bamboo forests, and massive exposed stone staircases.

The killer variable. Eccentric quad damage from long steep descents, paired with valley-floor humidity that spikes sweat rates.

VMM is famous for brutal climbs like Mount Silverstone. If your plan only counts weekly mileage, your quads will fail by km 30. The slippery mountain mud places enormous eccentric load on the quadriceps. Misty peaks lull you into thinking it's cool — until you drop back into the rice-terrace valleys and meet 30 °C with 85% humidity.

Scale weekly load by time-on-feet and vert ratio, not kilometres. Target ~55–60 m of climbing per km of running, with one weekly downhill repeat session to bulletproof the quads. Heat-acclimation sessions (sauna or overdressed Z2) in the final 4 weeks pay off enormously in the valleys.

Sweat rates spike in humid valleys, accelerating glycogen depletion. Hold 60–90 g of carbohydrates per hour from km 1, paired with aggressive sodium (600–1000 mg/hour) to prevent systemic cramping. Real-food breaks at aid stations — pho broth, salted rice cakes — combat gel fatigue.