Fat Ox. 48-hours — post

Lessons learned

Simen Holvik
7 min readNov 29, 2023

My notes ten days afte the race: I did not run the full 48-hours, but stopped after 41:30:35 hours and 360.98 km (224.3 mi). I had then the Norwegian record (357,919 km) in my pocket. But why did I not continue? I was feed up, and I did not see — at that point in time — that I could do another 34 km — in 6,5 hours to get the Nordic record (393,984 km). And I was very tired and afraid of injuries. Looking at it now; I should of course continued — and aimed for the Nordic record. That I feel sorry about now.

Anyway; below are my leassons learnt from that race:

Some pictures from the race.

(I) What did not work out!

1. Peeing to much in the beginning

In the first few hours, I was peeing a lot. Most likely this was due to drinking to much (more than 800ml per hour in the beginning). This perhaps did not align with the temperature and my sweat rate. For next time; make sure to do a sweat rate test under the race conditions. This will make sure that the fluid intake is more align with sweat rate. (I did a lot of sweat rate testing in Dubai as a preparation for Badwater 135, but I have not done such a test for normal / normal -hot conditions.)

2. Diarrhea after first solid meal

Race started 8am. At lunch I had a solid meal from Panda Express (a bowl of fried rice with orange chicken) and a Barq´s root beer. Soon thereafter, I had a diarrhea. Changed underwear and took to pills of Imodium. No problem after that.

Before the race, I had tried out the same bowl several times, but I had not tried eating that as a lunch after 4–5 hours of intensive running. Next time; make sure that the solid foods (I used fried rice with chicken for “lunch” and pasta with tomate sauce for “dinner”) are tried out as part of a training run. You need to run 4–5 hours, at race pace, and then eat the same food as planned for in the race. Need to implement this next time.

3. Thin carbon shoes did not work out at the concrete

I was surprised by how beaten up the legs were after running at the concrete. I think this was due to my choice of shoes. A very thin sole, combined with a stiff carbon plate — did not work out for me at this surface. My bad, I should have trained at concrete, and I have no one to blame. After 5–6 hours my legs did “not work anymore”.

Then I changed to a big shoe with a lot of cushion (still no drop) and that worked out for a while. But they turned out to be too heavy. Tried to change to a fast marathon shoe with a lot of cushion, but that pair was not small. (Makre sure to always bring shoes with 1- 1,5 size up from normal size). At the end I changed to a wide shoe cushion shoe with 4mm drop.

For next time, and for even longer race (e.g. 6 -days), make sure to bring more (and larger size) shoes (wide, lightweight with cushion). My normal size is US 10.5, and at this race I had 11,5 shoes. Make sure to bring a few at US 12,5 as well.

This is showing the first 260 km. Even if the pace was a bit high for the first five-six hours, I do not think it was to aggresive. I had following splits: Maraton: 3:23:26.75 (4:48 min/km), 50 k: 4:02:28.54 (5:08 min/km) and 80 k: 6:36:17.37 (5:19 min/km)

4. Carb intake dropped to only 30g at night

Plan for the race was 60 gram carbohydrate per hour. That worked out most of the time, but during the night that dropped down to only 30 gram. Need to be aware of this for next race. A potential risk.

5. To much time spent on eating the solid foods

For the solid food consumed (lunch and dinner), I was eating this while I was walking. Wated too much time here. Either I need to eat up faster, or I need to find a way to run while eating this out from the cup.

6. Tent / crew station

I only had my tent with me. For next time, and for bigger races, bring a large camping tent with sides to protect for wind and rain. Also bring a real camping bed.

7. A bit off my sodium target.

Ended up at 731 mg/L. Should have been closer to 1000 mg/L. Next time; take 1 electrolyte capsule for every 250ml of non-electrolyte drink I have!

(II) What did work out!

1. Crew

In general, the support crew worked out very well. Maybe next time, do not ask med what I want — just give it to me. Take even more control.

2. Fuel & hydration

Plan was 60 gram carbohydrate per hour, mostly with products from Precision Fuel and Hydration. That worked out really well.

Compiled by Precision Fuel & Hydration.

3. Micro sleep

At day two, I had 15 minutes with sleep. That worked out great. Felt that my brain was “re-adjusted”, and also my legs felt fresher. When I started to run I was really cold , but that quickly worked out. Absolutely someting to consider for next 48-hours race.

4. Carb loading period

Period before the race with carb loading (Tuesday, Wednesday and Thursday), and the pre-race breakfast worked out very good. No GI issues at start.

  • Mandag — low fat, high protein, low carb
  • Tirsdag — low fat, low protein, high carb
  • Onsdag — low fat, low protein, high carb
  • Torsdag — low fat, low protein, high carb
  • Fredag — race start 08:00
Carb loading started at Tuesday. The corresponsing gain weight.
Example (Monday) de-carb period.
Example (Wednesday) carb loading period.

5. Caffeine

Timed perfectly.


  • 1 x PF 30 Caffeine Del
  • 250ml x Black Coffee
  • 220ml x Dr Pepper


  • 1 x PF 30 Caffeine Gel (5am)


  • 500ml x Takeaway cup barq’s root beer.
  • 1 x PF 30 Caffeine Gel

6. Record

Even if the main goal did not work out, I was able to establish power and will to aim for the Norwegian goal. Very happy with that stamina.

7. Solid food worked out

I had fried rice with orange chicken for lunch, and spagetti with tomate sauce for dinner. Great stuff. No GI issues, except for the first lunch.

My lunch at day one day two.

(III) How do I feel?

Straing after the race I had a few blisters:

10 days later:

At day 8, 9 and 10 I have had in total 30 km of easy run. Feeling good, but still a bit stiff. But the most irritating issue is peeing. I *think* that my body is working on “something” (rabdomyolysis or something). I fell that my kidney and liver is in recovery mode. During nighttime, I need to go up 4–5 times to pee. This is normal for me after such races. It will last for a few weeks before going back to normal.



Simen Holvik

A professional Norwegian ultra runner, adventurer, speaker and writer