First 100K Ultramarathon Experience: A Complete Record from Registration, Preparation, to Finishing

100 kilometers. Back in the days before I started running, that number sounded like something from another planet. Yet after three years of running and four completed marathons, I decided to sign up for my first 100K ultramarathon. This is my complete record.

Why I Chose the Ultramarathon

After finishing my fourth marathon, I faced what many runners call the “post-race emptiness.” The marathon no longer made me nervous, and I began searching for the next goal that would get my heart racing. After watching a few ultramarathon documentaries, I was deeply moved by those runners who pushed through 24 hours in the mountains, and I decided to step into the world of ultramarathons.

Choosing a Race: Ultramarathon Options in Taiwan

Ultramarathon events in Taiwan have flourished in recent years. The major races include:

I chose the Fubon Taipei Ultramarathon because the urban course offers well-stocked aid stations and abundant medical resources, making it suitable for runners attempting their first 100K.

Preparation: The Distance from Marathon to Ultramarathon

Increasing Training Volume

The biggest difference in ultramarathon preparation lies in weekly mileage and back-to-back long runs:

• Weekly mileage: Gradually increased from 60 km/week during marathon training to 90–100 km/week
• Back-to-back long runs: A 30 km long run on Saturday plus a 20 km long run on Sunday, simulating the feeling of running under accumulated fatigue
• Night running practice: If the race includes a nighttime segment, you need to train your rhythm and mental adaptation for running in the dark

Gear Preparation

The gear requirements for a 100K ultramarathon far exceed those of a marathon:

• Hydration vest (10–12L): To carry water, nutrition, and spare clothing
• Headlamp: A primary light plus a backup, with battery capacity lasting 15+ hours
• Trail running shoes (if the course includes trail sections) or road running shoes (depending on the course)
• Insulation layer: Temperatures can drop sharply at night
• First-aid kit: Elastic bandages, blister patches, painkillers, sunscreen
• Energy supplies: 15–20 energy gels plus solid food (jelly, sandwiches, dates)

Race Day: A 12-Hour Journey

Before the Start

We gathered at 5 AM, with over 500 ultramarathon runners assembled in the starting area. The atmosphere was completely different from a marathon—quieter, more composed. Most ultramarathon runners don’t rush at the start; everyone knows the road ahead is still very long.

0–30K: A Pleasant Opening

The first 30 kilometers felt easy and enjoyable. I ran slower than my marathon pace (deliberately), taking in the scenery along the way and chatting with fellow runners. This is the most fascinating part of ultramarathons—it transforms running from a competition into a journey.

30–60K: Entering the “True Ultramarathon”

After passing the 30-kilometer mark, my marathon muscle memory kicked in, but two-thirds of the 100K still lay ahead. This stretch was the most mentally grueling: you know you can still run, but you also know you’re already tired. I told myself: “Just focus on the next aid station, don’t think about the finish line.”

60–80K: The Dark Hours

After 60 kilometers, night fell. I turned on my headlamp, and the world shrank to a small patch within the beam of light. Blisters began forming on the soles of my feet, and my thigh muscles grew slightly stiff. Every runner has their own struggle in this stretch. I found a fellow runner going the same pace, and we took turns talking to keep each other alert.

80–100K: The Power of Counting Down

After 80 kilometers, the math starts working in your favor—the thought of “only 20 kilometers left” carries more power than “still 20 kilometers to go.” My legs were heavy, but my heart felt light. In the final 2 kilometers, I gave every ounce of energy I had left to sprint, and tears streamed down my face involuntarily.

Finish time: 13 hours 22 minutes

Reflections After the Finish

The greatest takeaway from the 100K ultramarathon wasn’t the result, but a realization: the human body is far stronger than we imagine, and it’s our mental limits that are the true boundaries.

For friends who want to take on an ultramarathon:

1. Complete 3–4 marathons first to confirm your baseline endurance
2. Find a like-minded running partner to train with and keep each other accountable
3. Don’t rush into the hardest races; progress gradually
4. Remember: the finish line of an ultramarathon is never the end of the race—it’s the moment you tell yourself “I did it”

Related Reading

• My First Fubon Taipei Ultramarathon: A Beginner’s 100K Reflections
• Ultramarathon Basics: Transitioning from Marathon to 50K/100K Training
• The Complete Guide to Your First Road Marathon: From Registration to Finishing
• My First Marathon Finish: The Real Journey from Registration to 42 Kilometers