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Fuel plan · UTMB · 171 km

UTMB 171K fuel plan: 38 h

Anna’s fuel plan for the UTMB: 171 km and 10,000 m of climbing around Mont Blanc, finishing in 38 h. Here are her numbers for every hour and what she carries between aid stations.

An example plan. Your weight, pace and the weather will give different numbers, so work out your own and test them in training.

Runner: Anna, 40, woman
Weight: 58 kg
Experience: 11 years of running, 8 ultras before, the longest a 160K with about 6,500 m of climbing
Training: About 85 km a week
Race: UTMB, 171 km with 10,000+ m of climbing, August
Finish: 38 h, starting 17:00 and finishing about 07:00
Conditions: An evening start, so two nights in the mountains: warm valleys by day, freezing wind over the high passes after dark, and a second morning of running before the finish.

What are the numbers?

Worked out with the same maths as the UltraCalcPal app for a 58 kg runner, a 38 h finish, low effort and moderate weather, with altitude.

Per hour	Whole race
29 g carbs	1,102 g
467 ml fluids	17.7 litres
550 mg sodium	20.9 g

What does every hour look like?

The clock times assume a 17:00 start. After 22:00 the plan eases carbs and fluids, because appetite and thirst drop in the dark.

Hour	Clock	Carbs	Fluids	Sodium
1	18:00	29 g	467 ml	550 mg
2	19:00	29 g	467 ml	550 mg
3	20:00	29 g	467 ml	550 mg
4	21:00	29 g	467 ml	550 mg
5	22:00 (dark)	20 g	374 ml	550 mg
6	23:00 (dark)	20 g	374 ml	550 mg
7	00:00 (dark)	20 g	374 ml	550 mg
8	01:00 (dark)	20 g	374 ml	550 mg
9	02:00 (dark)	20 g	374 ml	550 mg
10	03:00 (dark)	20 g	374 ml	550 mg
11	04:00 (dark)	20 g	374 ml	550 mg
12	05:00	29 g	467 ml	550 mg
13	06:00	29 g	467 ml	550 mg
14	07:00	29 g	467 ml	550 mg
15	08:00	29 g	467 ml	550 mg
16	09:00	29 g	467 ml	550 mg
17	10:00	29 g	467 ml	550 mg
18	11:00	29 g	467 ml	550 mg
19	12:00	29 g	467 ml	550 mg
20	13:00	29 g	467 ml	550 mg
21	14:00	29 g	467 ml	550 mg
22	15:00	29 g	467 ml	550 mg
23	16:00	29 g	467 ml	550 mg
24	17:00	29 g	467 ml	550 mg
25	18:00	29 g	467 ml	550 mg
26	19:00	29 g	467 ml	550 mg
27	20:00	29 g	467 ml	550 mg
28	21:00	29 g	467 ml	550 mg
29	22:00 (dark)	20 g	374 ml	550 mg
30	23:00 (dark)	20 g	374 ml	550 mg
31	00:00 (dark)	20 g	374 ml	550 mg
32	01:00 (dark)	20 g	374 ml	550 mg
33	02:00 (dark)	20 g	374 ml	550 mg
34	03:00 (dark)	20 g	374 ml	550 mg
35	04:00 (dark)	20 g	374 ml	550 mg
36	05:00	29 g	467 ml	550 mg
37	06:00	29 g	467 ml	550 mg
38	07:00	29 g	467 ml	550 mg

What to carry between aid stations?

The legs use the average pace of the whole race, so the climbs take longer and the descents less than shown. The stations and distances are approximate: use the race's own guide for the exact ones.

Leg	Distance	Time	Carbs	Fluids	Sodium
Start to Saint-Gervais	21 km	4 h 40	135 g	1,895 ml	2,333 mg
Saint-Gervais to Les Contamines	10 km	2 h 13	64 g	902 ml	1,111 mg
Les Contamines to Les Chapieux	19 km	4 h 13	122 g	1,714 ml	2,111 mg
Les Chapieux to Courmayeur	28 km	6 h 13	180 g	2,526 ml	3,111 mg
Courmayeur to Champex-Lac	47 km	10 h 27	303 g	4,240 ml	5,222 mg
Champex-Lac to Trient	17 km	3 h 47	110 g	1,534 ml	1,889 mg
Trient to Vallorcine	9 km	2 h 00	58 g	812 ml	1,000 mg
Vallorcine to Finish	20 km	4 h 27	129 g	1,804 ml	2,222 mg

A mud-spattered runner in a red vest with arms raised and smiling, crossing the finish in the centre of Chamonix in early morning light, with a church tower and snow-capped Mont Blanc massif behind and cheering spectators behind the barriers. — The finish in Chamonix, early on the third morning.