Which shorts for trail and ultra running?
Written by Victor Michel — history enthusiast and passionate alpinist based in Chamonix. Published August 1, 2026
On a multi-hour ultra, shorts are chosen first for storage (gels, phone) and freedom from chafing, before looks. A built-in liner avoids an extra piece of underwear that chafes under the trail vest.
Pockets: the real selection criterion
On a long format, being able to reach a gel or your phone without stopping or opening the trail vest genuinely changes the race experience. Shorts with a zipped back or side pocket, sized for a modern smartphone, should be favoured for multi-hour formats.
Built-in liner or separate underwear?
Most trail shorts now include a technical liner sewn in, which avoids layering with classic underwear — a frequent source of chafing over a multi-hour format. Check that the liner lies genuinely flat at the seams before heading out on a long format.
| Criterion | Recommendation | Why |
|---|---|---|
| Fabric | Stretch synthetic, flat seams | Freedom of movement and chafe-free comfort over time |
| Pockets | At least 2, one zipped for the phone | Accessible storage without opening the trail vest |
| Liner | Built-in anti-chafe liner | Avoids an extra piece of underwear that catches |
| Length | Mid-thigh (about 12 to 15 cm inseam) | Trade-off between freedom of movement and protection from brush chafing |
| Water resistance | Light water repellency, no full waterproof membrane | The mandatory waterproof over-trousers take over in heavy rain |
Editorial selection
Top 5 recommended shorts for trail and ultra running
Five references covering short formats as well as multi-hour ultras.
Salomon — Sense Aero / Cross
Competition cut, built-in liner, zipped back pocket for the phone.
Compressport — Trail Racing
Light-compression specialist, stretch fabric, good support without excessive compression.
Raidlight — Activ / Ultra
French brand specialising in ultra-distance, storage designed for long formats.
The North Face — Summit Series
Competition range, lightweight technical fabric, anti-chafe liner.
Decathlon (Kiprun / Evadict) — Trail range
Recognised value for money among amateur runners, multiple pockets depending on the model.
Independent editorial selection, with no commercial link or partnership.
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FAQ
What shorts length for trail running?
Mid-thigh (about 12 to 15 cm inseam) is the most common trade-off between freedom of movement and protection from vegetation chafing in the woods.
How many pockets do you need on trail shorts?
Two at a minimum, one zipped and sized for a smartphone. On an ultra, a back pocket accessible without stopping is a real plus.
Is a built-in liner essential?
It's not mandatory but avoids layering with classic underwear, a frequent source of chafing over a multi-hour format.
Do you need waterproof shorts for the UTMB?
No: shorts remain lightly water-repellent. It's the mandatory waterproof over-trousers that protect against heavy rain.
Fitted or loose shorts for an ultra-trail?
A fitted cut limits chafing under the trail vest and bouncing of pocket contents; a too-loose cut favours irritation over long distances.