Shinetsu Five Mountains 100 Mile 2026 | What I Did to Get There, and What Was Still Missing
I finished the 2026 Shinetsu Five Mountains 100 Mile.
My time was 25 hours 57 minutes, 37th overall. Last year I ran 27 hours 20 minutes, so this was about 1 hour 23 minutes faster.
I reached my minimum goal of finishing under 26 hours. But it wasn't the race I had pictured. Ideally I wanted the low 25s. From early on I spent my legs in the mud, and in the second half I couldn't run as much as I had planned.
Even so, my second-half pace improved on last year, and I made it to the finish without completely falling apart. There was training that worked, and there were issues that only became clear through the race.
In this article I'm not presenting what got me this result as the right answer. Instead, I want to go back through, in order, what I saw as my problem, how I trained, and what happened on race day.
Making "a pace I could hold forever" faster
What I focused on for the 100 miles was not the ability to run fast for a short time, but how fast I could move at an intensity that felt like "I could keep going like this forever."
Of course, you can't run 160 km at the same pace. You move differently on climbs, descents, forest roads and pavement. Still, I thought the foundation for Shinetsu was raising the speed I can run at a low intensity, and being able to hold that state for a long time.
My reference was *Training for the Uphill Athlete* by Scott Johnston and co-authors. I didn't apply the weekly plans in the book as they are, though. I rebuilt them around my weaknesses, how quickly I recover, the work at the shop, and the time I had.
The weakness I had in mind before the race: steep climbs
Looking back on last year's race, I thought my weakness was steep climbing.
Shinetsu has a lot of runnable sections, but it also has steep climbs. If I use up my legs there, I can't run the way I'm good at on the forest roads and gentle descents that follow. So my goal wasn't just to climb steep sections faster.
Climb efficiently, don't use up my breathing and legs, and keep something for the runnable sections that follow. Rather than speed on any one climb, I wanted a way of climbing that helps me move fast over the whole race.
AeT: the boundary that marks the top of the low-intensity range
The feeling of "I could keep going like this" alone makes training intensity vary from day to day. So the reference I used was AeT (aerobic threshold), the upper limit of the low-intensity range.
Lactate isn't something that only appears at high intensity. It is produced even at low intensity, and used and cleared as an energy source. As intensity rises, a first turning point appears where blood lactate begins to rise steadily above its resting level. This is LT1. In practice, AeT is treated as a boundary close to LT1, and to VT1, which is determined from expired gas. But because the measurement and the way the point is identified differ, they are not exactly the same thing.
The term "Zone 2" also needs care. In the four-zone system for mountain endurance athletes that I referred to, AeT is the top of Zone 2. In the three-zone system often used in research, on the other hand, Zone 1 is below LT1 and Zone 2 runs from LT1 to LT2. The same name can point to different intensity ranges.
Zone displays on watches also differ in how zones are divided and calculated depending on the model and settings, and don't necessarily match these systems. So in this article I write "below AeT," "around AeT" and "around LT2" instead.
To estimate my AeT I used a heart rate drift test. On a treadmill at 1% incline, or on a flat loop, I held a steady pace for about 60 minutes and compared the average heart rate of the first and second halves. It doesn't measure lactate directly; it estimates AeT indirectly from how heart rate changes at a constant speed.
I used a rise of around 5% as a guide. If heart rate rose a lot, I considered that the intensity may have been too high; if the change was small, I tried a slightly faster speed on another day. Because heat, fatigue, sleep, and how the heart rate monitor is worn all affect the result, I didn't decide from a single test, but repeated it under matched conditions.
After repeated tests, I estimated my pace around AeT at about 4:25/km on a treadmill at 1% incline. That was indoors with no wind, though, so I don't assume it would be the same pace on the road. On trails the grade and surface change even more, so I adjusted intensity by watching my breathing and how much I had in reserve, as well as heart rate.
What I came to feel here is that the top of the low-intensity range isn't necessarily a speed you can casually keep running at. For me it came out at around 4:25/km. Even with breathing to spare, running at that speed puts a real load on the legs.
The more training raises the speed you can run at low intensity, the less you can think, "it's low intensity, so I can run this fast every day." For me, sustained running around AeT was not an easy jog but training done with a purpose. I kept days of 60 to 90 minutes at this intensity separate from days where I ran easier to prioritize recovery.
Hill repeats to build running fitness and leg endurance
I had built up a fair amount of low-intensity training. On top of that, I thought work around LT2 was also needed to raise the speed I can hold around LT1 even further. What I used to raise my overall running fitness was repeats on trail climbs.
LT2 is the second boundary, where blood lactate starts to rise sharply as intensity goes up. In this workout I used heart rate around LT2 as the upper limit, climbing for about 10 minutes and running back down. That was one set, and I repeated it about three times.
While climbing, I feel a burning load in my legs as well as in my breathing. Climbing for 20 to 30 minutes at that intensity was hard, so I split it into roughly 10-minute pieces. Because long descents sit in between, it is different from a threshold run that holds a steady intensity on the flat. It aimed at both a stimulus around threshold and the endurance to keep producing force on a climb.
I brought this into ROCK STEPPERS MOUNTAIN CLUB training, and we did it together every week. Members racing Shinetsu did it too, but I myself didn't manage enough sessions. Even so, I did feel that running uphill had become much easier and that I was getting stronger on climbs.
Once you get used to the same workout, I think the load needs revisiting. Extending the climb from 10 to 15 minutes, going from three reps to four, raising the speed — I want to progress the workout to suit my condition at the time.
Muscular endurance so I don't use up my legs on the climbs
To avoid overusing my legs on steep climbs and keep enough to run afterwards, the other thing I brought in was training aimed at muscular endurance, called ME (Muscular Endurance).
What I did was climb a steep slope carrying about 10 kg. I used a nearby slope that takes about 30 minutes to climb. I actually wanted to keep climbing a bit longer, but there was no suitable slope close by, so I worked with that length.
Where the hill repeats above put a stimulus on both the heart and lungs and the legs using heart rate around LT2 as a guide, this one added load to each step of the climb with weight, aiming to build the muscular endurance of the legs.
I also used long hikes as practical muscular endurance training. In August I did these mountain trips:
- August 9: 9.79 km, 7 h 46 min, 859 m elevation gain
- August 10: 13.13 km, 8 h 25 min, 1,353 m elevation gain
- August 25: 23.86 km, 6 h 46 min, 1,986 m elevation gain
- August 26: 14.17 km, 11 h 09 min, 1,598 m elevation gain
Not only running, but moving in the mountains for long hours two days in a row like this was also part of my preparation for Shinetsu.
Not by weekday: hard sessions only after recovering
I started training seriously for Shinetsu around June.
Unlike before, I didn't decide that "I'll always do this workout on this day every week." At the same time, I didn't just train however I felt each day without any rules.
In my mind, muscular endurance, threshold runs and long runs counted as hard sessions. And I made it a rule to keep at least two days at low intensity or below before any hard session.
If I couldn't do a hard session on the planned day because of work or my schedule, I moved it to the next day. What matters isn't keeping to the weekday, but doing a purposeful session in a recovered state.
Only the long runs couldn't easily be pushed to the next day, because of the time I could set aside and the schedules of the people I ran with. In that case I protected the long-run date first and made sure to avoid hard sessions from at least two days before.
As an exception, I deliberately built back-to-backs into my training. Since the purpose is to move again while fatigue remains, they are treated differently from normal hard sessions. Not consecutive days that happened by accident because the schedule slipped — I only did them when there was a reason to run consecutive days, and I thought of them as one workout including the recovery before and after.
Rather than the satisfaction of having pushed hard, leave yourself in a state to do the next session as intended. Over these three months, I think what I valued most was not training volume itself but recovery.
Using long runs to check what short sessions can't show
Low-intensity running, threshold runs and muscular endurance work let you train each ability separately. But in a 100 mile, you have to combine them while fatigued.
After hours of moving, can I still switch from a climb to running the forest road? Will my stomach hold up while I keep fueling? Does gear bounce or chafe more as time goes on? At what I think is the same intensity as early on, how do my heart rate and movement change? You can't check these things in short sessions. That's why I put in long runs.
I don't think simply running long distances is enough. The aim of a long run was not to produce a distance figure, but to find the changes that happen as time passes, and to test the terrain, fueling, gear and pacing I'd use on race day in a single session.
What I paid attention to was the change in terrain: climbs, runnable forest roads, descents. Could I run after finishing a climb? Could I avoid overdoing the first half and keep the same movement for the second? Could I hold that intensity while taking in my race-day fuel?
During the preparation period I did sessions like these:
- July 25: 28.52 km, 6 h 20 min, 1,986 m elevation gain
- August 11: 60.43 km, 7 h 13 min, 2,273 m elevation gain
- August 13: 50.26 km, 7 h 52 min, 1,722 m elevation gain
- September 5: about 39 km, 5 h 40 min, about 1,200 m elevation gain
- September 6: 41.41 km, 4 h 41 min, 1,243 m elevation gain
For long runs, I also did sessions repeating a loop of about 10 km. Because you pass the same terrain, it's easy to compare how much you dropped off between the first and second half. Beyond the distance and elevation figures, it gave me material to review fueling, heart rate and second-half pace.
On long runs I actually took in the fuel I'd use in the race. Not holding out until I ran out of energy without fueling, but practicing keeping a runnable intensity while eating. I also checked what intensity my stomach would accept and what timing put the least strain on it.
Just because you're running 100 miles, I don't think you have to run 100 km in one go in training. If running 100 km means I can't train properly for a week afterwards, that's not efficient for me. Besides keeping up 40 to 60 km sessions, I thought that adding back-to-backs as an exception, moving again across days with fatigue carried over, made it easier to create the load I was after while balancing recovery.
About three months of training volume, and the final weeks
For about three months leading into Shinetsu, including hikes, I averaged about 110 km a week, about 4,000 m of climbing and about 20 hours of moving time. It wasn't the same every week; I combined low-intensity running, climbing work and long runs around work, mountain trips and how recovered I was.
Two weeks before the race I ran about 38 km, and in the final week about 27 km. It was the time to cut volume for the taper, but I feel I cut too much.
The truth is, work was extremely busy and I couldn't find time to run. I lost a lot of sleep, and I wasn't in great shape physically. I didn't get to shed fatigue as planned and stand on the start line in perfect condition.
Three plans, and controlling the first half by heart rate
Before the race I made three split plans: a good day, a standard day and a bad day.
I based them on runners in past results who were close to my level, held back in the first half, and stayed relatively steady into the second half. I also used AI to compare split data, but the table wasn't meant for chasing target times. It was a range for judging where I was when things went off plan.
In the first half of the race, my guide was a heart rate of around 130 on runnable flats, around 140 on climbs, and not going much over 150 even on steep climbs. These are my personal numbers. Heart rate changes with temperature, fatigue and condition, so the same numbers can't be applied to other people.
In the second half, fatigue can make it harder for heart rate to rise. I didn't force my output up just to match the numbers; I prioritized my breathing, the state of my legs and changes in how I was moving.
Fueling and gear, also checked in training
What I had in mind for fueling was continuing to take in the carbohydrate needed to keep running into the second half, without wrecking my stomach. This time I planned for 75 to 100 g of carbohydrate per hour, or about 300 to 400 kcal in energy. I didn't really include calories from fat or protein in this fueling calculation, and focused on how much carbohydrate I could take in.
On long runs I used the same fuel as in the race, checking what intensity I could keep fueling at, how much I could take in at once, and what timing put the least strain on my stomach.
The core was Oiena and gels. Diluting Oiena with water and sipping it from a 500 mL flask worked well for me. The basic plan was to drink one bottle over two hours, and add one gel per hour on top of that. At aid stations I also had rice balls and miso soup.
The first half went roughly to plan, but in the second half my intake naturally dropped. I couldn't take in as much as in the first half, and there were moments when I felt that putting in any more would cause stomach trouble. I didn't stick to the planned amount to the end, but I kept taking in what I could tolerate and got through without major stomach problems. How to keep fueling in hot conditions is still an open question for me.
What I valued in gear was being able to focus on running for a long time. Not just lightness or individual features, but whether it stays comfortable through long use and is easy to handle when I need it.
With shoes, I think not only about how much rebound they have, but also stability, fit, and how they change over long use. Also, since I ran without support this time, I had to carry my own fuel until the next drop bag. Being able to carry that much and get at it while running was important in choosing gear.
Fueling and gear alike: use them in training, confirm what suits me, and only then take them into the race. I introduce the specific gear, how it felt to use, and the details of my fueling in another article.
Holding back my speed in the mud in the first half
After all that preparation came race day at the Shinetsu Five Mountains 100 Mile. It poured from the start until around 2 a.m. The trails were slippery, and I moved forward bracing with my legs again and again.
I didn't fall, but I kept catching my body as it started to slip, and from the first half I began to feel the load in my legs. It was a feeling different from usual, and I sensed fatigue coming earlier than normal.
At that point I could still run. But I felt that if I carried on like this, fatigue would keep building and I might fall apart partway. So I deliberately didn't raise my speed, and held back with the aim of saving my legs for the second half.
I don't know how much that decision affected my time. But I was adjusting my pace by thinking not only about whether I could run now, but whether I could keep running beyond that.
In the second half, I couldn't hold speed on the runnable sections
Even after holding back, I couldn't run the way I wanted in the second half. My heart and lungs weren't struggling at all, yet my legs found it hard to produce force. That feeling gradually grew stronger.
Not being able to hit the same speed as early on in the second half of a 100 mile isn't unique to this race. But this time I feel that the unusual load on my legs I'd sensed in the first half carried through to the second half.
Looking back after the race at this year's official results and my COROS data, the gap to the leading runners opened up most not on the climbs but on the forest roads and gentle descents near the end. The last 12 km or so has little climbing and is runnable, but it took me 1 hour 51 minutes.
My COROS data also showed that near the end my cadence was almost unchanged from early on, while my stride had shortened. That matches my own feeling that it was less about my heart and lungs struggling and more that my legs were finding it hard to produce force.
That said, I don't take the fact that I hadn't experienced race-day distance and descent in training as simply a lack of preparation. I think my preparation for this race was sufficient. On top of that, the mud in the first half put an unusual load on my legs, and its effect remained into the second half. That's how I see it.
That effect can't be separated out from the data alone. But when bad conditions make you use your legs differently than usual, how do you keep the load down and save something for the second half? That's what I want to think about next.
What worked, and what I want to carry forward
This year I improved my second-half pace on last year. The course layout differs, so a simple comparison isn't possible, but in a distance-adjusted estimate my second half from Kurohime on was about 1 minute 20 seconds per km faster than last year.
Raising my ability to keep running at low intensity. Building up climbing work until running uphill became easier. Practicing fueling over and over in training. And making sure to recover before hard sessions. I felt the preparation I'd put in was paying off.
In the race, I also made the call to hold back when I felt the load on my legs in the first half. Even so, I couldn't run the second half the way I had pictured. I feel I need to separate being well prepared from being able to respond to what happens on race day.
Next: saving my legs for the second half, bad conditions included
I think my preparation for this race was sufficient. Even so, the mud in the first half put an unusual load on my legs, and I feel it showed up in the second half. What I want to think about next is how to keep running legs for the second half even in situations like that.
In training, I'm also thinking about ways to add more volume. Running a roughly 40 km course I normally use to simulate Shinetsu once in the morning, then, after a break, once more in the afternoon or evening. Not a two-day back-to-back, but a double session within one day.
Using the same course also lets me compare how my running changes between the first and second run. With options like this, while balancing recovery, I want to build the ability to keep running into the second half.
