How to Train for the OCC by UTMB | Qualify, Stones & Strategy
- High Peak Running
- Oct 23
- 8 min read
1. Race Overview & Context
What is the OCC?
OCC is one of the Finals races in the UTMB World Series. It is essentially the “shorter ultra” (mid-distance ultra) final, sitting between the lottery-accessible 20 km and the longer CCC / UTMB races. montblanc.utmb.world+1
For 2026, OCC is listed as ~57 km with ~3,500 m of positive elevation gain.
The maximal allowed race time is long (~ 14h 30m as of the 2026 edition) to account for technical terrain, weather, and altitude effects.
Because of its distance and elevation, it sits in a “sweet spot” where the standard physiological predictors from road (VO₂max, lactate threshold, running economy) still correlate strongly with outcome, yet the demands of trail (technique, strength, fatigue resistance) also become increasingly important.
History & Position in UTMB
UTMB (Ultra-Trail du Mont-Blanc) is the flagship “finale” event of the UTMB World Series.
Over recent years, UTMB has reorganized into a World Series model:
• Finals races: UTMB, CCC, OCC (these are the Chamonix/region races in August)
• Majors: One “major” per continent (Americas, Europe, Asia-Pacific, Oceania). These Majors carry extra weight (double “running stones”) and some automatic slots for top finishers.
• Other UTMB World Series Events: Many trail races around the world, which award “Running Stones” that feed into the lottery for the Finals.
Thus, the OCC is not just an isolated race — it is the Final in the 50 km category of the UTMB World Series.
2. How to Qualify / Get into OCC (Finals)
To enter the OCC (or any of the UTMB Finals races), you typically need two things:
At least 1 Running Stone (earned by finishing qualifying UTMB World Series races).
A valid UTMB Index in the relevant category (in your case, for the 50 km / “50K category”)
What is a Running Stone?
A Running Stone is like a “ticket” into the UTMB Finals lottery. The more you collect, the more lottery chances you get. You do not get Running Stones from completing the Finals races themselves (i.e. you don’t earn stones by finishing OCC, CCC, or UTMB in Chamonix).
Stones are earned by completing UTMB World Series races (or “Majors”) in the 20K, 50K, 100K, or 100M categories. At Majors, you earn double the number of Running Stones compared to a standard World Series event.
When you enter the lottery for OCC/CCC/UTMB, you “wager” your stones:
If you win, your stones are spent (they drop back to zero).
If you don’t get drawn, you keep your stones and can use them next year.
Note: There is some community confusion / discussion around whether your stones must be recent (within 2 years). Some sources note that “only 1 stone acquired in the past two years is mandatory” for lottery entry. But officially, stones have “no expiration date” — you just can only wager stones earned before December 31 of the prior year. help.utmb.world
What is the UTMB Index?
The UTMB Index is a performance metric calculated from your results in UTMB World Series / UTMB Index-certified races over the past 24–36 months.
To enter OCC, you must hold a valid UTMB Index in the 50K / 50 km category (or at least have done a 20 km index race, as some sources allow stepping up).
The index is recalculated as you race more on qualifying races; it affects your priority and entry chances.
Direct Qualification & Elite Spots
Beyond the lottery, there are automatic qualification slots given to top finishers in Majors and World Series events:
The top 3 men and women in 50K / 100K / 100M categories in UTMB World Series Events often win automatic entry to the Finals.
In each Major, some category winners, age-group winners, and top finishers (e.g. top 10) get direct qualification.
UTMB also introduced a Top Elite Status (from September 2025) that gives elite runners an extended qualification period (Jan 2025 to June 2026) to secure Finals participation.
Summary of Qualification Steps (for OCC)
Here’s your path as a non-elite runner:
Be careful: races abroad, travel, cost, and logistics matter — choose events that suit your calendar and budget.
3. Training Strategy for OCC (≈ 57 km / +3,500 m)
Because the OCC is right in the “mid-ultra / mountain ultra” zone, your training has to balance:
Aerobic engine (VO₂max, threshold, economy)
Strength & durability (to cope with climbs, descents, impact)
Technical trail / terrain skills
Nutrition, fuelling, and fatigue resistance
Below is a practical, phase-based framework, with pointers to recent research and key considerations.
Key Determinants & What to Emphasize
From available research and coaching experience:
VO₂max: Builds your ceiling. Among well-trained ultra runners (especially in the 50–80 km range), VO₂max still shows a strong correlation with performance. (Ehrström et al., 2018)
Lactate / ventilatory threshold (LT / VT): More predictive of what fraction of that VO₂max you can sustain. Many coaches place primary emphasis here.
Running economy / efficiency: On road and trail, being economical (lower oxygen cost at given pace) gives you “free speed.”
Strength, especially lower limb & core: To absorb downhill forces, muscle fatigue, uneven terrain.
Fatigue resistance, nutrition, injury resilience: Your systems for repair, recovery, muscle integrity, gut tolerance, and mental resilience matter immensely in a long technical race.
A 2023/2024 study on slope running found that cardiorespiratory and muscular factors may shift in relative importance depending on gradient — suggesting that uphill/vertical-specific training is crucial. arXiv
Also, new wearable-based modelling (2025) shows that VO₂ dynamics can now be estimated from smartwatches & heart rate data with reasonable accuracy — enabling more real-time training feedback. arXiv
Thus, integrate both classic physiological training and modern monitoring/data where possible.
Periodization: Phases & Focus
You can structure your training into macro-phases (approximate durations, adapt as needed):
Base / Foundation (3–4 months)
- Emphasize volume, building aerobic capacity, low-intensity miles/hours.
- Develop muscular endurance with light strength work and hills/trails.
- Introduce technique / trail skills, footwork, downhill confidence.
Build / Specificity (2–3 months)
- Maintain base volume, begin threshold / tempo work, longer hill intervals.
- Introduce VO₂max intervals (3–8 min efforts) but don’t overdo them.
- More race-simulation on terrain, vertical work, back-to-back days.
- Increase strength / plyometrics to handle eccentric loads (downhill stressing).
Peak / Sharpening (3–4 weeks)
- Taper slightly, but include high-quality sessions (VO₂max, threshold).
- Simulate pace efforts on terrain, possibly race rehearsals (cutback plan).
- Focus on recovery, race tactics, fueling, and gear testing.
Race / Recovery
- Execute your plan, then have a structured recovery to bounce back and learn.
Sample Workouts & Guidelines
Here are sample workouts and training principles that align with current evidence and coaching best practices.
VO₂max / High-Intensity Work
Use intervals like 4 × 4 min at ~90–95% VO₂max with 3 min jog rest (classic “4×4”) — effective, manageable, and provides stimulus without over-fatigue. (Echoed in Runner’s World commentary).
Also, sprint interval training (e.g. 30s–1min “all out” efforts) may deliver strong improvements for already well-trained runners (K Jin et al. 2025). PMC
Limit total VO₂max work to ~20% or less of your weekly training load in build/peak phases, so you don’t burn out.
Threshold / Lactate Tolerance / Tempo Work
Sessions of 20–30 min continuous at “comfortably hard” (the pace where speech is limited to 1–2 words) are excellent.
Or interval versions: 3 × 10 min hard + 2 min easy, or 2 × 15 min.
As your fitness improves, you can extend those to 40 min or do tempo “blocks” on hills/trails.
The literature supports that LT training (ability to process lactate) is central for sustainable performance in long distances. (Vijay review, 2024) mjssm.me
Volume & Long Runs
Long runs should be done over trail / elevation similar to OCC profile. Include uphill, technical descents, uneven surfaces.
Once per few weeks, consider a longer day (e.g. 4–6 h) with moderate pace, broken terrain, back-to-back days to simulate fatigue.
Use progressive long runs (gradual increase in time / distance) with some sections at “cruise” pace (slightly harder than easy).
Strength, Plyometrics, and Muscular Resilience
Two strength sessions per week targeting knee extensors (quads), glutes, hamstrings, calf / plantar flexors, core. Use relatively heavy loads (8–12 reps) for strength-endurance (rather than maximal power) — this gives resilience over long fatigue.
Add eccentric-focused exercises (e.g. controlled downhill steps, eccentric calf lowering) to better tolerate downhill loading.
Plyometric drills (bounding, hops) help neuromuscular responsiveness and running economy.
Technique, Trail Skills & Adaptation
Practice uneven terrain, technical descents, rock-hopping, foot placement. Simulating the trail conditions you’ll face is critical.
Work uphill pacing: learn how to climb efficiently (shorter strides, efficient posture).
Use sessions on similar grade / vertical routes to develop vertical economy, as vertical running economy becomes differentiating. Calibrated Coaching
Nutrition, Gut Training & Fueling
In training, consistently practice fueling strategies (carbohydrate intake, hydration) under load, especially on long runs. You want your gut to adapt to absorbing during stress.
Research suggests very high carbohydrate intake (up to ~120 g/h) can reduce muscle fatigue and improve performance, if tolerable (Urdampilleta et al.). montblanc.utmb.world
Also, somewhere in your training, experiment with low-glycogen or “train low” sessions to enhance fat metabolism, but carefully to avoid overtraining / muscle damage. (Caveats in Ramon et al., Stellingwerff)
Monitor recovery markers (sleep, HRV, muscle soreness) so that nutrition supports adaptation rather than becoming a stressor.
Putting It All Together — Example Week (Build Phase)
Here’s a hypothetical build-phase week (for a relatively experienced athlete):
Adjust based on fatigue, terrain access, travel, etc.
4. Race Strategy & Tactics for OCC
Pacing is critical: You’ll want to run below threshold for the early sections, saving for climbs and final portions.
Manage energy / fueling: Start fueling early, don’t let yourself “crash.” Use your practiced nutrition plan.
Technical sections & downhill: Be careful on descents — avoid over-braking (which fatigues muscles) and pick your lines.
Adapt to weather / altitude: Be prepared for changes in conditions, and have contingency pacing plans.
Mental phases & checkpoints: Break the race into segments, set micro-goals (aid stations, climbs, transitions).
Know the cut-offs: The race has cut-off checkpoints; staying within them is as important as speed.
5. Common Pitfalls & Coaching Tips
Overemphasis on VO₂max: Many runners chase “speed” but neglect threshold and volume; that often backfires. Prioritize threshold and durability first.
Under-training strength: You’ll pay the price in the latter half.
Neglecting terrain specificity: Training all on roads then switching to technical mountain trails is risky.
Poor recovery / overtraining: Fatigue accumulation can derail you — monitor, adjust, rest.
Fueling surprises: Never try new food or drink on race day — all nutrition strategies must be validated in training.
Lottery and qualification timing: Plan your qualifying races well ahead of registration windows. Some races sell out early.
A Little Extra Support from Us
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