Chongli 168 (Final): What Finishing My First 100-Mile Trail Race Taught Me About the Body

Hello everyone,

I still have a few thoughts I'd like to share after finishing the Chongli 168 100-mile trail race. The experience gave me a lot to reflect on. I've already written three previous posts about the event, and this will be the final one.

This time, I also used AI to help me better understand some of the physical experiences I had during the race. I compared my own observations with explanations based on exercise physiology. While AI is not a substitute for medical advice or scientific literature, I found it useful for organizing what I experienced and pointing me toward concepts that are generally consistent with current sports science.

Does a 100-Mile Race Leave You Feeling Better Than Expected?

One thing surprised me after finishing.

Unlike after many marathons or even 100-kilometer races, I felt relatively normal once I crossed the finish line. I could walk back to the hotel without much difficulty, take a shower, pack my belongings, sleep, travel to the airport the next day, and generally move around without the stiffness I had expected.

At first, I wondered whether my fitness had improved dramatically, but that explanation didn't seem convincing.

After asking AI, I received an explanation that aligned with what is commonly discussed in endurance sports. During shorter endurance events, accumulated fatigue and metabolic byproducts often contribute to muscle soreness. In much longer races, however, the body has more time to clear some of these byproducts while the event is still in progress. That may partly explain why some runners feel less immediate muscle stiffness after finishing a 100-mile race than after a marathon or a 100-kilometer race.

Of course, that does not mean a 100-mile race is healthier.

The longer duration places far greater cumulative stress on the joints, tendons, ligaments, and soft tissues. In my case, I only realized afterward that both of my feet had become swollen, especially my left foot. Fortunately, the swelling did not significantly affect my mobility, but it was a reminder that feeling less sore does not necessarily mean the body has sustained less stress.

After the Lowest Point, Fat Becomes a More Important Energy Source

Another question I had was why I actually felt stronger during the later stages of the race.

Around the 130-kilometer mark, I noticed that I was moving surprisingly well.

The explanation I received centered on the body's changing energy systems.

During marathons and many ultramarathons, glycogen stored in the muscles and liver serves as the primary fuel source. As glycogen becomes depleted, runners often experience the well-known sensation of "hitting the wall."

In extremely long races such as a 100-miler, the body gradually shifts toward relying more heavily on fat oxidation for energy. This transition is neither immediate nor effortless, and many runners experience a particularly difficult period before their metabolism adapts more effectively. Once that transition becomes more established, some athletes report feeling more stable again, even though overall fatigue continues to accumulate.

I checked this explanation with two different AI systems because I wanted to see whether the answers were consistent. Both described a similar physiological process, which also matched what I experienced during the race.

One interesting takeaway is that very long trail races require substantial fat metabolism. That does not make ultrarunning a practical weight-loss strategy for most people—training volume, recovery, nutrition, and injury risk all need to be considered—but it does highlight how differently the body fuels itself during extremely long endurance events compared with shorter races.

Ironically, when I weighed myself after the race, I was about two kilograms heavier than before the start.

The most likely explanation was temporary fluid retention. My body was visibly swollen in the race photos. I had also eaten at nearly every checkpoint throughout the course, while digestion naturally slows during prolonged endurance exercise. The number on the scale clearly did not reflect changes in body fat.

Why Did the Hallucinations Become So Intense?

Another experience I wanted to understand was the hallucinations near the end of the race.

According to AI, visual hallucinations are not uncommon during very long ultramarathons, particularly when prolonged sleep deprivation, physical exhaustion, and metabolic stress combine.

The descriptions matched my experience surprisingly well.

Earlier in the race, ordinary patches of grass began to look like people, snakes, or strange creatures. I would stop, look more carefully, and realize they were only plants.

Toward the end, the hallucinations became much stronger. At times, distinguishing between what was real and what was not became genuinely difficult.

For future races—especially UTMB later this year—I plan to take this much more seriously. Experienced ultrarunners use different strategies, including brief sleep breaks when necessary. If hallucinations become severe again, taking a short rest may be the safest decision rather than trying to push through.

That was another valuable lesson from this race.

My First 100-Mile Finish Is an Important Personal Milestone

This will probably be my final post about Chongli 168, so I'd like to end by reflecting on what this finish means to me.

The race itself was extremely demanding.

The weather included heavy rain, hail, low temperatures, dense fog on the mountain, and long stretches of muddy trails. Under these conditions, finishing became a significant challenge for many runners.

Crossing the finish line also marked an important milestone in my own running journey.

Completing a 100-mile race qualifies runners to enter many other long-distance trail events around the world. Some races require previous finishes at shorter qualifying distances before allowing registration for longer formats. Having completed my first 100-miler opens opportunities that were not previously available to me.

For many runners, this distance represents an important step in their development, and I now understand why.

Progress Matters More Than Talent

I've been running for many years, but I've never considered myself naturally talented.

When people ask about my marathon personal best, my answer has always been around four hours. Among many experienced runners, that's considered fairly average, or even below average.

I've never been the fastest runner in the group.

Last year, I entered this same race but withdrew after approximately 100 kilometers. It was the first time I had ever failed to finish a race, and I was deeply disappointed. I remember writing afterward that I wanted to train more seriously and come back one year later.

That's exactly what I did.

Over the past year, my training became much more consistent. Most weekends included two long runs whose combined distance was close to a marathon. My monthly mileage increased from just over 100 kilometers to around 200 kilometers.

For me, that represented a meaningful change in commitment.

Finishing this 100-mile race doesn't make me an elite runner, but it does remind me that steady, disciplined training can lead to meaningful progress over time.

My Next Running Goal

If I had to summarize what comes next, I think my focus may shift toward improving my marathon performance.

Rather than immediately chasing another even longer ultramarathon, I'd like to lower my marathon time to around 3 hours and 30 minutes.

Breaking three hours remains a long-term goal.

Given where I am today, I know that would require much more training, greater consistency, and a larger time commitment than I currently have available. For now, improving step by step feels like a more realistic approach.

I also believe that becoming a stronger road runner will ultimately improve my trail running as well.

Finishing this race has given me greater confidence, and that's something I value.

A 4:00 a.m. Finish Line I'll Remember

After the race, there was considerable discussion about the weather and whether the organizers should have suspended the event.

The conditions were undeniably difficult.

Heavy rain began shortly after the start and continued for a long time. Higher elevations brought fog, strong wind, low temperatures, and challenging terrain. Trail running always involves environmental risks, and opinions naturally differed about how the event should have been managed.

While I understand why these discussions took place, my own experience left me with a deep appreciation for the organizers and volunteers.

At the second-to-last aid station, I spoke with one of the volunteers. By then, I had been awake for more than 40 hours, and so had many of the volunteers. They were still supporting runners long after the fastest athletes had finished.

Later, I watched an interview with the race director, who became emotional while talking about the responsibility of managing an event with thousands of participants spread across mountainous terrain. Coordinating logistics and prioritizing safety under rapidly changing weather conditions is an enormous challenge.

One small detail stayed with me.

I crossed the finish line at around 4:00 a.m., when most events would already feel quiet and nearly empty.

Instead, there were still volunteers and a cheering team waiting at the finish. They welcomed every runner with the same enthusiasm they had shown throughout the event.

That moment meant a great deal to me.

After more than 44 hours on the course, hearing people cheer as I crossed the finish line provided a sense of warmth and encouragement that I'll remember for a long time.

It's easy to assume that we only run for ourselves, but everyone appreciates genuine encouragement after such a demanding effort.

To me, that finish-line atmosphere reflected the dedication of the people who had worked behind the scenes throughout the race.

Whether or not I return to Chongli 168 next year—I may need a little more time to recover before making that decision—I'm grateful for the experience.

Final Thoughts

Completing Chongli 168 taught me far more than how to cover 100 miles.

It showed me how the body adapts during extreme endurance events, how important consistent training is, and how much support from volunteers, organizers, friends, and fellow runners matters along the way.

Most importantly, it reminded me that meaningful progress usually comes from patience rather than shortcuts.

Thank you for reading.