Report on a 35km training walk in extreme heat and self-made app verification for the 100km summer walk

Hello, this is Kamosawa❗️

I have started full-scale summer walking training for the upcoming "Summer Karuizawa and Joshu Nakasendo Ultra Walking" in August.

To put it briefly, a 35km walk in 30°C heat was a parade of challenges... haha.

However, I think it was a huge gain to realize these issues before the actual event.

This time, I will share my realistic training record from Saturday, July 11, 2026, and the insights I gained there.

🏃‍♂️ This training course

• Date: Saturday, July 11, 2026, Sunny/Cloudy

• Temperature: 30°C

• Distance: 35km

• Route: Home - Serigaya Park - Tsurumi River Headwaters - Tama Yokoyama Road - Yakushiike Park - Home

To get my body used to the heat, I took a big loop around my home, visiting local landmarks and tourist spots I usually pass by.

At Serigaya Park, I managed to get all 6 "Poké Lids" (Pokémon manhole covers) I had been aiming for, which really boosted my spirits❗️

It's not just about walking long distances; incorporating this kind of "personal entertainment" along the way makes even grueling training much more fun, doesn't it?

🥵 Challenge #1: It's just too hot to eat

The biggest enemy this time was the "heat." Sweat was pouring down, and my throat was constantly parched.

Above all, I completely lost my appetite along the way...

I managed to keep my sanity by eating ice cream and ice, but if this happens during the actual 100km walk, I will definitely run out of energy.

"Not being able to eat" is one of the most dangerous signs in a 100km walk.

I keenly felt the need to find ways to "keep eating," even if just a little, for the actual event.

I had been avoiding them until now, but I plan to actively incorporate easy-to-swallow jelly drinks into my trail food.

😴 Challenge #2: The return of sleepiness

The sleepiness that plagued me during my last walk has returned.

It seems that when I continue intense exercise on an empty stomach, I get hit with intense sleepiness, perhaps as a brain defense mechanism.

I feel that eating (to prevent bonking) is directly linked to combating sleepiness as well.

Next time, I will try walking while setting more specific intervals for replenishing not just water, but also salt, minerals, and oral rehydration powder 💪

📱 Challenge #3: Noticing a bug in my self-made app

This time, I also used the opportunity to test the self-made navigation app for the 100km walk that I improved in Fable5.

After actually using it, I immediately found an interesting issue.

This app is designed to calculate the predicted arrival time at the next checkpoint based on the pace of the previous section.

Because of that...

"The predicted arrival time for the first checkpoint doesn't appear right after the start"

I realized this very basic oversight, haha.

But finding these kinds of bugs that you can only notice in real-world conditions is the true value of a practice walk, isn't it?

The app itself worked very smoothly, so I have already fixed the arrival prediction logic! Now I can use it in perfect condition for the actual event in Karuizawa.

🤝 Let's enjoy the steady preparation

A 100km walk in the summer is truly grueling, but the process of tackling challenges one step at a time is actually the most exciting part.

What kind of replenishment and countermeasures do you all use for summer training? Please let me know in the comments if you'd like!

Let's continue to prepare steadily for the big day together 💪