Expert Training Guide

100K

The Ultimate Endurance Test

Distance 100km

Miles 62mi

Duration 10-16hrs

fact_check Prerequisites

50K+ Completed (at least one 50K or 50-mile ultra finish) 70-80 km weekly volume comfortable Can run/walk 5-6+ hours continuously Ready for extended physical and mental challenge

psychology What 100K Actually Means

Time: 10-16+ Hours

Could be longer on technical terrain. Plan for the worst.

Night Running

Most 100Ks involve running in darkness. Train for it.

Weather Changes

Conditions can shift dramatically over 12+ hours.

Body Breakdown

Something will hurt. Blisters, chafing, muscle damage—manage, don't panic.

menu_book Intensity Glossary

EASY

Conversational pace—can speak in full sentences.

LONG

Extended run measured in hours, not kilometers.

B2B

Long runs on consecutive days—essential for 100K.

NIGHT

Run in darkness with headlamp—practice required.

HILLS

Run with elevation gain—practice power hiking.

RACE

Your 100K ultramarathon.

20-Week Training Schedule

Week 1 / 20

Phase 1: Base Building (70-80 km/week)

Rest

-

—

Easy

Easy run

60 min

Rest

-

—

Hills

Hill work

60 min

Rest

-

—

Long

Long run

2.5 hrs

Easy

Easy run

60 min

Weekly Total ~70km

Rest

-

—

Easy

Easy run

70 min

Rest

-

—

Hills

Hill work

65 min

Rest

-

—

Long

Long run

3 hrs

Easy

Easy run

60 min

Weekly Total ~75km

Rest

-

—

Easy

Easy run

75 min

Rest

-

—

Hills

Hill work

70 min

Rest

-

—

Long

Long run

3.5 hrs

Easy

Easy run

65 min

Weekly Total ~80km

Rest

-

—

Easy

Easy run

60 min

Rest

-

—

Easy

Easy run

50 min

Rest

-

—

Long

Long run

3 hrs

Easy

Easy run

50 min

Weekly Total ~55km

Recovery Week: Let your body adapt. Long run progression: 2.5 hr to 3 hr to 3.5 hr to 3 hr (recovery) to 3.5 hr.

Rest

-

—

Easy

Easy run

80 min

Rest

-

—

Hills

Hill work

75 min

Rest

-

—

Long

Long run

3.5 hrs

Easy

Easy run

65 min

Weekly Total ~80km

Rest

-

—

Easy

Easy run

80 min

Rest

-

—

Hills

Hill work

75 min

Rest

-

—

B2B

Back-to-back day 1

4 hrs

B2B

Back-to-back day 2

2 hrs

Weekly Total ~90km

Back-to-Back Weekends: Running long on consecutive days is the most ultra-specific training you can do. It teaches your body to perform on tired legs.

Rest

-

—

Easy

Easy run

85 min

Rest

-

—

Hills

Hill work

80 min

Rest

-

—

Long

Long run

4 hrs

Easy

Easy run

70 min

Weekly Total ~95km

Rest

-

—

Easy

Easy run

90 min

Rest

-

—

Hills

Hill work

80 min

Rest

-

—

B2B

Back-to-back day 1

4.5 hrs

B2B

Back-to-back day 2

2 hrs

Weekly Total ~100km

Rest

-

—

Easy

Easy run

70 min

Rest

-

—

Easy

Easy run

60 min

Rest

-

—

Long

Long run

3.5 hrs

Easy

Easy run

60 min

Weekly Total ~70km

Rest

-

—

Easy

Easy run

90 min

Rest

-

—

Hills

Hill work

85 min

Rest

-

—

B2B

Back-to-back day 1

4.5 hrs

B2B

Back-to-back day 2

2.5 hrs

Weekly Total ~105km

Rest

-

—

Easy

Easy run

90 min

Rest

-

—

Hills

Hill work

85 min

Rest

-

—

Long

Long run

5 hrs

Easy

Easy run

70 min

Weekly Total ~105km

Rest

-

—

Easy

Easy run

95 min

Rest

-

—

Hills

Hill work

90 min

Rest

-

—

B2B

Back-to-back day 1

4 hrs

B2B

Back-to-back day 2

2.5 hrs

Weekly Total ~110km

Rest

-

—

Easy

Easy run

90 min

Rest

-

—

Night

Night run with headlamp

2 hrs

Rest

-

—

Long

Longest run of plan

6 hrs

Easy

Easy run

60 min

Weekly Total ~110km

Week 13: Your 6-hour run is the longest of the plan—the ultimate confidence builder. Practice night running with headlamp.

Rest

-

—

Easy

Easy run

85 min

Rest

-

—

Easy

Easy run

75 min

Rest

-

—

B2B

Back-to-back day 1

4.5 hrs

B2B

Back-to-back day 2

2 hrs

Weekly Total ~100km

Rest

-

—

Easy

Easy run

80 min

Rest

-

—

Easy

Easy run

70 min

Rest

-

—

Long

Race simulation - full nutrition and gear

4 hrs

Easy

Easy run

60 min

Weekly Total ~90km

Race Simulation: Run your exact nutrition plan, wear race gear, practice aid station routine, include a night section with headlamp. This is your dress rehearsal.

Rest

-

—

Easy

Easy run

70 min

Rest

-

—

Easy

Easy run

60 min

Rest

-

—

Long

Long run

3 hrs

Easy

Easy run

50 min

Weekly Total ~70km

Rest

-

—

Easy

Easy run

60 min

Rest

-

—

Easy

Easy run

50 min

Rest

-

—

Long

Long run

2.5 hrs

Easy

Easy run

45 min

Weekly Total ~50km

Rest

-

—

Easy

Easy run

50 min

Rest

-

—

Easy

Easy run

40 min

Rest

-

—

Long

Long run

2 hrs

Easy

Easy run

40 min

Weekly Total ~35km

Rest

-

—

Easy

Easy run

45 min

Rest

-

—

Easy

Easy run

35 min

Rest

-

—

Long

Easy long run

90 min

Easy

Easy run

30 min

Weekly Total ~20km

Rest

-

—

Easy

Easy shakeout

40 min

Rest

-

—

Easy

Easy shakeout

30 min

Rest

-

—

Rest

Complete rest

—

Race

100K ULTRAMARATHON

100km

Taper Wisdom: 5 weeks of taper might feel excessive, but 100K demands it. You'll feel restless and doubt your fitness—this is normal. The fitness is already banked.

route Race Day Pacing Strategy

0-25km Pace: Deliberately Slow

25-50km Pace: Sustainable

50-75km Pace: The Grind

75-100km Pace: Whatever It Takes

restaurant Nutrition Strategy for 100K

restaurant

250-350 Calories Per Hour

• More calories than a 50K because you'll be out there longer.
• Your stomach must be trained for this volume.
• Start eating after the first 2 hours.

bakery_dining

The Mix: 50/50

• 50% gels/chews for quick energy, 50% real food for satisfaction.
• Sandwiches, potatoes, fruit, soup—whatever your stomach tolerates.

water_drop

Hydration: 500-800 ml/hour

• Critical—hyponatremia is dangerous.
• Use electrolytes consistently.
• Strategic caffeine in the second half.

science

Practice Everything

• Every long run is nutrition training.
• Never try anything new on race day.
• Your gut needs to be trained just like your legs.

warning Critical Pitfalls to Avoid

Starting Too Fast

The first 25K should feel embarrassingly easy. If you're running with the pack, you're probably going too fast.

Neglecting Night Training

Most 100Ks involve running in darkness. Practice with your headlamp, know your gear, and train your mind for the dark hours.

Underfueling Early

By the time you feel hungry, it's too late. Eat on schedule, not by feel. 250-350 calories per hour is mandatory.

Ignoring Crew/Pacer Value

At 100K, support helps tremendously. A pacer in the second half and crew at aid stations can be the difference between finishing and DNF.

After the 100K

Next Goal

Recover Properly

1-2 weeks no running, 4-6 weeks easy only, 2-3 months before next hard effort. 100K takes a serious toll.

Next Goal

Run Another 100K

Apply lessons learned. Different terrain, better execution, faster time.

Next Goal

Go for 100 Miles

The ultimate ultra distance. If you finished 100K, you have what it takes.

Key Takeaways

check_circle 100K is a different sport—respect the distance
check_circle Back-to-back training is essential
check_circle Eat constantly—250-350 cal/hour
check_circle Night running needs specific practice
check_circle Mental strategies matter as much as fitness
check_circle Support helps—crew and pacers are valuable
check_circle The finish line waits—keep moving and you'll get there