Bear 100 Training Plan: Master 161km and 6700m of Elevation

The Bear 100 is one of North America's most formidable 100-mile ultramarathons, spanning 161 kilometers across high-altitude mountain terrain with 6700 meters of elevation gain. Taking place in late September, you'll face the dual challenges of high elevation and rapidly cooling temperatures as autumn descends on the mountains. The 36-hour cutoff is generous but demands respect—this is not a race you can walk casually and finish within time. The mountain and trail terrain means technical footwork matters as much as aerobic fitness. Success at Bear 100 requires specific preparation that goes beyond standard ultramarathon training. You'll need to build power on uphills, develop confidence on descents, practice moving efficiently through thin air, and condition your body for the relentless climbing that defines this course.

Altitude is the Bear 100's defining characteristic. Running at elevation demands physiological adaptation that cannot be rushed. If you live at sea level or moderate elevation, you need a structured altitude preparation plan beginning at least 12 weeks before race day. The most effective approach combines live-high-train-low methods with race-simulation workouts performed at elevation. If traveling to altitude for training is impractical, focus on repeated hill repeats and long climbs at your home elevation, then arrive at the race location 7-10 days early to begin acclimatization. During these pre-race days, run easy 30-45 minute sessions to allow your body to produce more red blood cells and adjust oxygen utilization. Avoid hard training during the first 3-4 days at altitude; your perceived exertion will be significantly higher and recovery will be compromised. The key is arriving with enough time to adapt without so much time that the adaptations fade before race day. Your fueling strategy must account for altitude's suppressed appetite—you'll feel less hungry but need more calories. Practice eating small, frequent portions of calorie-dense foods during your altitude training runs.

With 6700 meters of elevation gain compressed into 161 kilometers, the Bear 100 is essentially a continuous climbing effort. Approximately 42% of your race will be spent ascending, often at grades that demand power rather than pure aerobic capacity. Building specific climbing strength requires dedicating 8-10 weeks to power-focused training. This involves hill repeats (4-8 minutes at threshold effort on 8-12% grades), long sustained climbs (20-40 minutes on moderate 6-8% grades), and power endurance sessions that combine climbing with technical terrain. The terrain being mountain and trail rather than road means you need to develop footwork confidence on rocky, uneven surfaces. Many runners trained exclusively on roads or smooth trails struggle with the technical demands of true mountain running. Incorporate trail running into at least 40% of your weekly volume beginning 16 weeks out. Practice descending on technical terrain under fatigue—this is where most Bear 100 runners lose time and risk injury. Run down rocky trails when your legs are already tired from the day's climbing. This trains the eccentric muscle contractions needed for safe, efficient downhill movement at race pace.

The Bear 100's combination of altitude, cold, and duration creates a perfect storm for digestive upset. Many runners who can fuel perfectly during a flat 100-miler discover their stomach rebels at altitude with heavy calorie loads. Your race nutrition strategy must be built and tested during training, not discovered on race day. Start your training runs with a full stomach (breakfast 2-3 hours before) and practice consuming 200-300 calories per hour during efforts lasting 3+ hours. At altitude, your metabolism actually increases, so you may need 300-400 calories per hour during the latter half of the race. Focus on easily digestible carbohydrates: energy gels, sports drinks, rice cakes, and simple carbs from aid stations rather than solid foods that demand significant digestion. Practice your race nutrition during at least three 4-5 hour training runs completed at similar effort levels and conditions to what you'll face at Bear 100. Test specific products you'll use at aid stations; don't experiment with new foods or fuels on race day. Hydration must be disciplined but not excessive—aim for 500-750ml per hour of fluid depending on temperature and terrain. At altitude with cool September temperatures, overhydration is a real risk. Carry electrolyte supplements to prevent hyponatremia during the long effort.

With a 36-hour cutoff on a 161km course, most runners will face significant darkness. If you're targeting a sub-24-hour finish, you'll run through the night. If you're aiming for a sub-36-hour completion, you may face 8-12 hours of nighttime running across two nights. Running efficiently in darkness requires specific preparation. Beginning 10 weeks before the race, complete at least 3-4 long runs that include 2-3 hours of darkness (either very early morning or evening, extending into night). This trains your circadian rhythm adjustment and builds confidence with your lighting setup. Use the same headlamp and batteries you'll use in the race so you understand brightness, beam pattern, and battery life. Test your night fueling strategy—many runners find eating more difficult in darkness and experience nausea more easily. Practice consuming gels and liquids with a headlamp on; the experience is different from daytime fueling. If you have a crew supporting you, brief them on night running logistics: you'll be slower, less communicative, and potentially delirious. Establish clear signals for when you need support versus when you need space. Consider a second pair of shoes if you're running two nights; wet feet in darkness is a psychological and physical disaster. Some runners find a brief 20-30 minute nap at an aid station restores mental clarity during a second night—test this during training if you think you'll attempt it.