OCC Training Plan (57 km): 24 Weeks to Shine at the Foot of Mont-Blanc

The OCC (Orsières-Champex-Chamonix) is a dream for thousands of trail runners every year. With its 57 km and 3,500 m of positive elevation gain, this race is the ideal gateway into the UTMB Mont-Blanc universe. But make no mistake: behind its status as the "shortest" of the Chamonix week's events lies a demanding course, set between Swiss valleys and spectacular panoramas of the Mont-Blanc massif 🏔️

This 24-week training plan will guide you step by step, from building your aerobic base to the finish line on the Promenade du Fori. Whether you're aiming for a comfortable finish or a specific time, you'll find the keys to structured and progressive preparation here.

Understanding the OCC: The Course Requirements

Before planning your training, it's essential to understand what awaits you on the course:

• Distance: 57 km
• Positive elevation gain: 3,500 m
• Negative elevation gain: approximately 4,100 m (the finish in Chamonix is lower than the start in Orsières)
• Cut-off time: 14h30
• Start: Orsières (Switzerland), Thursday morning
• Finish: Chamonix (France)

The profile is not a simple out-and-back in the mountains. The course is a series of ascents and descents through the Val d'Entremont, Champex-Lac, Trient, then crosses the French-Swiss border at Col de Balme before climbing to La Flégère—the final challenge before the last descent to Chamonix. The technicality of the trails and the altitude (with sections above 2,000 m) add a layer of complexity that requires specific preparation.

The Plan's Fundamental Principles

Periodization in 3 Blocks

The 24-week plan is divided into three 8-week blocks, each organized in cycles of 3 weeks of progressive load followed by one week of recovery (reduced load). This structure allows your body to absorb training stress without accumulating chronic fatigue.

Progressive Weekly Volume

The volume evolves according to your training block:

• Block 1 (weeks 1-8): 4 to 6 hours per week
• Block 2 (weeks 9-16): 6 to 8 hours per week
• Block 3 (weeks 17-24): 7 to 10 hours per week (peak), then taper

This volume is a guideline and should be adapted to your training history, availability, and recovery signals. If you use tools like heart rate variability (HRV), you can fine-tune your daily load.

Session Frequency

Plan for 4 to 5 sessions per week, including:

• 2 to 3 runs (including one long run on the weekend)
• 1 quality session (intervals or threshold)
• 1 strength training or cross-training session
• Optional: 1 recovery bike ride or active hike

Block 1 — Building the Aerobic Base (Weeks 1 to 8)

Objectives

To develop your base endurance, strengthen your fundamental muscular qualities, and lay the cardiovascular foundation needed to handle the subsequent blocks.

Sample Workouts

Long Run (weekend): 1h30 to 2h15 at base endurance pace (zone 1-2). Prioritize hilly, even moderate, terrain. Alternate between walking and running when the gradient exceeds 15%. The goal is not speed but time on your feet 🚶‍♂️➡️🏃

Short VMA Session: After a 20-minute warm-up, do short intervals to boost your VO2max:

• Weeks 1-4: 8 to 10 × 30"/30" (30 seconds fast / 30 seconds recovery)
• Weeks 5-8: 2 × (6 × 1'/1') with 3 minutes of recovery between sets

Easy Run: 45 to 60 minutes with completely comfortable breathing. This is the core of your polarized training—don't neglect it in favor of intense sessions.

Strength Training: 30 to 40 minutes, twice a week. Target the key muscle chains for trail runners:

• Squats, forward and side lunges
• Step-ups on a bench (to simulate climbing)
• Dynamic core work (plank with arm/leg movements)
• Eccentric quadriceps work (Bulgarian squats, slow descents)

Validation Race

At the end of Block 1, schedule a 10k road race or a cross-country race to assess your aerobic fitness and get an initial speed benchmark.

Block 2 — Specific Development (Weeks 9 to 16)

Objectives

To increase your ability to sustain a prolonged effort on ascents and descents, develop your threshold endurance, and introduce the first big-elevation runs.

Sample Workouts

Long Run with Elevation Gain: 2h15 to 3h00, incorporating 800 to 1,200 m of D+ into the run. Work on your climbing technique (posture, step frequency, use of poles) and your descending technique (look far ahead, stay relaxed, quick foot turnover).

Threshold Session: Gradually replace short VMA sessions with aerobic threshold work:

• 3 × 10' at threshold (half-marathon pace) with 3' recovery
• Progress to 2 × 20' at threshold with 4' recovery

Hill Repeats: Find a 3- to 5-minute climb. Perform 6 to 10 repetitions at a sustained intensity (noticeable but controllable shortness of breath), jogging back down. This is a fundamental exercise for the OCC—the race is a relentless series of climbs 💪

Back-to-Back Weekend (once a month): On Saturday, do a long run with elevation gain (2h30-3h). On Sunday, a shorter endurance run (1h-1h30). This "back-to-back" trains your legs to run on a pre-fatigued body.

Cross-Training

Road or mountain biking (1 to 2 hours) is an excellent low-impact supplement for cardiovascular work. A fast hike in the mountains on the weekend can also replace a long run if you don't have access to elevation during the week.

Validation Race

Schedule a 25 to 35 km trail race (with 1,000 to 1,500 m D+) between weeks 14 and 16. This is your mid-preparation dress rehearsal: test your gear, nutrition, and pacing strategy.

Block 3 — Sharpening and OCC-Specific Preparation (Weeks 17 to 24)

Objectives

To reach your peak fitness, simulate race conditions, and begin the final taper to arrive fresh and sharp in Orsières.

Weeks 17-20: Peak Load

Hike-Run Session: This is THE key workout for OCC preparation. For 3h30 to 5h00, alternate between fast hiking uphill and running on descents and flats, exactly as you will during the race. Aim for 1,500 to 2,000 m of D+ in the session.

Downhill-Specific Session: The 4,100 m of negative elevation gain in the OCC destroys quads. Train specifically for it:

• 30 to 45 minutes of technical downhill running on single-track trails
• Work on progressive speed: start slowly, accelerate with each repetition
• Alternate between steep and runnable descents

Intensified Back-to-Back Weekend: Saturday, a long hike-run session (4h-5h, 2,000 m D+). Sunday, a hilly 1h to 1h30 run. This is the last big block—savor it 😊

Weeks 21-22: Pre-Taper

Reduce your volume by 30% compared to your peak. Maintain intensity with shorter sessions:

• 1 hill session (6 × 3') to maintain muscular pop
• 1 long run of 2h00-2h30 maximum with some elevation gain
• 2 easy runs of 45 minutes

Weeks 23-24: Final Taper

This is the most counter-intuitive phase: the less you do, the better. Reduce volume by 50 to 60% compared to your peak.

• Week 23: 3 sessions maximum—1 50' run with 4 × 30" strides, 1 1h15 hilly run, 1 40' easy run
• Week 24 (race week): 2 short 30' runs early in the week, then complete rest on Wednesday and Thursday before the start

Use this phase to finalize your logistics, check your mandatory gear, and mentally visualize the course.

Nutrition and Hydration: Race Strategy

Before the Race

In the 3 days before the OCC, slightly increase your intake of complex carbohydrates (pasta, rice, sweet potatoes) without disrupting your habits. The night before, have an early, light dinner. On the morning of the race (wake up around 5:30 AM for an 8:15 AM start), eat a breakfast you've tested in training: white bread, honey, a banana, and coffee for those used to it ☕

During the Race

Aim for 60 to 80 g of carbohydrates per hour from the very first hour. Plan to have:

• Gels or fruit purees (1 every 30-40 minutes)
• An isotonic drink (500 ml/hour depending on the heat)
• Solid food at aid stations (cheese, banana, dried fruit) to vary textures
• Salt tabs if conditions are hot (in August in Chamonix, the thermometer can exceed 30°C in the valley)

Golden Rule: NEVER test a new food or gel on race day. Everything must be validated in training.

Gear and Mandatory Equipment

The OCC has a list of mandatory gear that is checked at the start. Here are the key items to incorporate into your training:

• Trail vest/pack: 8 to 12 liters is sufficient. Train with the same pack you'll use on race day to avoid chafing.
• Poles: Highly recommended for the OCC. The climbs to Col de Balme and La Flégère are long—poles can save 15 to 20% of muscular energy in your legs.
• Waterproof jacket: The weather at altitude can change drastically in minutes. Choose a jacket that is lightweight but truly waterproof (not just water-resistant).
• Survival blanket, whistle, headlamp: Mandatory even if you plan to finish in daylight.
• Trail running shoes: Opt for a model with good cushioning and an aggressive outsole. The trails between Trient and Col de Balme are technical and potentially wet.

OCC Race Strategy

Breaking Down the Course

Mentally, divide the OCC into 4 segments:

1. Orsières → Champex-Lac (km 0-15): The start. Begin BELOW your target pace. The trap of the OCC is to go out too fast on the first climbs. Stay clear-headed.
2. Champex-Lac → Trient (km 15-30): The heart of the course. A series of climbs and descents. Fuel regularly and maintain a steady rhythm.
3. Trient → La Flégère (km 30-47): The hardest part. The climb to Col de Balme is long and mentally challenging. Walk the climbs without guilt, and run whenever the terrain allows.
4. La Flégère → Chamonix (km 47-57): The final descent. Relax your shoulders, let your legs flow. Enjoy the view—you've earned it 🎉

Managing Cut-off Times

With a 14h30 cut-off, you have a comfortable margin if you're aiming for 10 to 12 hours. But don't get complacent: the long mid-race climbs can eat into your buffer faster than you think. Keep an eye on your watch at the intermediate checkpoints.

A Typical Week at a Glance

Typical Week Block 1 (aerobic base)

• Monday: rest
• Tuesday: easy run 50' + strength training 30'
• Wednesday: VMA session (30"/30" × 10)
• Thursday: rest or bike/swim 45'
• Friday: hilly run 55' + core work 15'
• Saturday: long run 1h45 on hilly terrain
• Sunday: rest or active walk

Typical Week Block 2 (specific development)

• Monday: rest
• Tuesday: run 50' + strength training 35'
• Wednesday: threshold session (3 × 10')
• Thursday: bike or swim 1h
• Friday: hill repeats (8 × 4')
• Saturday: long run 2h30 with 1,000 m D+
• Sunday: easy run 1h (back-to-back)

Typical Week Block 3 (OCC-specific)

• Monday: rest
• Tuesday: run 50' with 6 progressive accelerations
• Wednesday: technical downhill session 1h
• Thursday: rest or easy bike ride 1h
• Friday: hilly run 1h + core work
• Saturday: hike-run 4h with 1,800 m D+
• Sunday: recovery run 1h15

Mistakes to Avoid

After coaching hundreds of trail runners for their first OCC, here are the most common pitfalls:

• Neglecting downhill work: Many plans focus on climbing. However, it's the 4,100 m of negative elevation that finishes off unprepared legs.
• Increasing volume too quickly: Respect the rule of no more than a 10% increase per week. Overuse injuries (shin splints, tendonitis) often strike between weeks 6 and 12.
• Skipping recovery weeks: Progress happens during rest, not during effort. Your body needs these lighter weeks to consolidate adaptations.
• Starting too fast on race day: The excitement at the start in Orsières, the energy of 2,500 runners around you... The temptation is strong. Resist it. The first 15 kilometers should be run with absolute restraint.
• Testing new gear during the race: Shoes, pack, poles, nutrition—everything must be tried and tested. No improvising.

Adapting the Plan to Your Profile

You are a trail running beginner (less than one year of experience)

Extend the plan to 30-32 weeks by adding 6-8 weeks of additional aerobic base building before Block 1. Reduce the volumes by 20% and replace the back-to-back weekends with a single long run.

You are an experienced road runner transitioning to trails

Your cardiovascular base is solid, but your muscles are not used to the specific demands of trail running (elevation, unstable terrain). Emphasize eccentric strength training and incorporate technical terrain runs from Block 1.

You are aiming for a top 25% finish

Add a 5th weekly session, increase long run volumes by 20%, and schedule two preparation races (a 30k trail and a 40-50k trail). Threshold work becomes central to your Block 2.