Chihuahua by UTMB® 135km Training Plan & Race Guide

The Chihuahua by UTMB® represents a significant endurance test at 135km with sustained mountain terrain. This is a major step up from standard marathons, demanding not just aerobic capacity but the ability to maintain effort across multiple days of effort and technical trail navigation. The race sits within the UTMB® World Series, meaning it shares the organizational excellence and challenging course design that defines this elite circuit. Understanding the mountain terrain, trail conditions, and the sustained elevation demands is critical for building an effective training strategy. Unlike road ultras, the Chihuahua course requires mastery of technical footing, pace management on varied gradients, and mental resilience across the full distance. The trail running component means every kilometer demands focus and strength from stabilizer muscles that road running doesn't develop. Your preparation must account for mountain-specific adaptations including quad endurance, ankle stability, and the metabolic demands of constantly changing elevation.

A successful 135km preparation program spans 20-24 weeks of structured training, divided into distinct phases that build from base endurance to race-specific intensity. Your training must progress from foundational aerobic capacity through mountain-specific strength work, then into peak volume and taper phases. This progression ensures your body adapts to sustained effort, trail-specific demands, and the psychological challenges of extended mountain running. The emphasis shifts from traditional tempo work toward long, slow distance runs on varied terrain, back-to-back weekend efforts, and sustained climbing repeats. Mountain ultras require different energy systems than road races—you'll need to develop comfort with sustained low intensity, metabolic flexibility for fueling during extended efforts, and mental strategies for the inevitable low points across 24+ hours of racing. Unlike 50k training, 135km preparation demands genuine long runs reaching 30-40km on technical terrain, multiple sustained climbs weekly, and specific work on descending technique to manage fatigue and injury risk. Your aerobic capacity ceiling must expand significantly, while simultaneously building the toughness to push through discomfort when it matters.

While specific elevation details for the Chihuahua course require checking the official UTMB® website, mountain ultras typically feature sustained altitude that impacts both training and race day performance. If the course includes significant altitude, your preparation must include specific acclimatization strategies. Even if you cannot train at genuine altitude, you can simulate the physiological demands through interval work, sustained climbing efforts, and high-intensity threshold sessions that elevate lactate and demand oxygen efficiency. Mountain environments present variables beyond elevation—temperature swings between day and night, exposure to wind, and technical footing that demands constant attention. Your training should include sessions in varied weather conditions, running in different temperatures, and practicing your gear layering strategy. The mental component of altitude running is substantial; runners often struggle psychologically when pace slows significantly on climbs. Building the mental framework to accept slower speeds while maintaining effort and focus is as important as physical conditioning. Check the official race website at https://chihuahua.utmb.world for current elevation profile data, which will help you tailor your training intensities and pacing strategy.

A 135km mountain ultra lasting 24-48+ hours demands a fundamentally different nutrition approach than shorter races. Your strategy must balance caloric intake with digestive tolerance during extended effort, varying intensities, and potentially changing environmental conditions. Early in the race (first 8-10 hours), you can rely on concentrated gels, bars, and sports drinks that provide quick calories without requiring significant digestion. As fatigue accumulates and intensity drops, your stomach typically tolerates more solid foods—this is when you shift toward easy-to-digest real food options. Mountain ultras present unique nutrition challenges: cooler temperatures may make you less thirsty but equally dehydrated, technical terrain reduces eating opportunities, and hunger signals become unreliable after 12+ hours of effort. Your training must include long runs where you practice your complete race nutrition protocol—not just the food, but the drinking schedule, the timing of fuel intake, and how to maintain consistency through discomfort. Aid station spacing at UTMB® events is typically well-distributed, but you should check the specific Chihuahua course details to understand how often you'll have resupply opportunities. Practice eating while moving, eating when you're not hungry, and maintaining your fueling schedule when your mind is tired. Electrolyte management becomes critical in extended efforts, particularly if the course includes significant elevation. Your kidneys' ability to process fluids increases with acclimatization to long efforts, so prolonged training runs teach your body how to handle race-day fluid volumes.

The Chihuahua by UTMB® 135km is as much a mental challenge as a physical one. At some point—usually between hours 12-20—your motivation will crash, your legs will feel impossibly heavy, and continuing will feel foolish. Every successful 135km finisher has encountered this moment and learned to navigate through it. Your training must build the psychological framework to recognize these low points as normal and temporary, not signals to quit. Break the race into manageable segments: 50km milestones, 12-hour checkpoints, or specific course sections. Having multiple finish lines in your mind makes the overall distance feel less overwhelming. Build a race mantra or mental strategy that works for you—some runners focus on breathing, others on the next aid station, still others on their support crew or a personal motivation. Your pacing strategy must account for the mountain terrain. Unlike road marathons where even pacing works, mountain ultras demand intelligent effort distribution. Early climbs should feel genuinely easy; you'll feel tempted to push harder, but restraint early compounds benefits throughout the race. Descents should be controlled and technical—many runners gain back time here, but only if they've managed their quads through the climbs. By kilometer 80-100, your pace will naturally slow significantly, and this is expected and healthy. Mental resilience isn't about maintaining your early-race pace; it's about maintaining your effort and focus regardless of speed. Practice this in training by running longer efforts at consistently lower intensities, where you learn to find satisfaction in completion over speed.