Mammut’s Aenergy Trail Endurance Ultra Low laughs at snow, ice, and nasty trails

Introduction to the Mammut Aenergy Trail Endurance Ultra

JOHN: I received the Mammut Aenergy Trail Endurance Ultra Low at an absolutely perfect time, the week of the Delmarva Ultra Challenge 100k (DUC). We were also under a blanket of snow across the East Coast, so I needed a shoe that could handle cruddy, cold, icy, messed-up conditions.

Both the other reviewers received this shoe in a size that didn’t work right, but my UK M10 somehow fit great. So once I checked it out and knew I would be okay on the race in it, I went for it. I love getting a good story when reviewing shoes.

My only connection with Mammut is working in outdoors stores — I loved the gear but could never afford it. I always viewed it like, “dang, I wish I had that stuff,” and was envious of the people who bought it for leisure so they would look cool in coffee shops.

Well, guess what? I got to use it on an actual, brutal adventure. I put this shoe through absolute torture. 100k of snow, ice, and everything not-so-nice. Let’s see how it did.

JON: Thanks to being married to a former REI employee, I have known about Mammut for a while, but they seldom come across my radar. I tend to associate them with mountaineering and hiking; trail running not so much. They do seem to be rising up the ranks of gorpcore as Arc’teryx gets increasingly popular and people need something “lesser known” to latch onto.

The Mammut Aenergy Trail Endurance Ultra is part of the Swiss brand’s new lineup of trail running shoes for 2026, which is looking to change that. I was equally excited and skeptical upon receiving the shoe.

What we like about the Mammut Aenergy Trail Endurance Ultra

JOHN: As mentioned earlier, the other reviewers had an issue with the fit, and I’m going to talk about that more in the next section. Weird fit aside, this shoe is comfortable even in absolutely miserable conditions. I had to do a brutal water crossing in the middle of the night, and it drained perfectly, leaving my feet feeling good for the next 40 miles.

I’m very impressed with how protective this shoe is, too. I kicked a lot of stuff in the first portion of the 100k, and it didn’t hurt. I never felt like I was going to fall at all and I stayed upright. This shoe gave me a lot of confidence. It didn’t feel speedy, the average I ran in this shoe was a 9-12 min pace but it worked extremely well and if I needed to speed hike I also got in some very fast paces.

I really want to highlight something about this shoe. I purchased yaktrax because of how tough the course had the potential to be (and many runners out there needed them) but I didn’t need to use them because the grip on this shoe was so good. I was extremely impressed.

JON: This shoe was a blast to run in from top to bottom. The durability gave me no doubt that it will have a very long life.

I’ll say that the knit upper felt stiff at first, but eventually stretched out a bit and now fits like a glove. The material breathed exceptionally well, and the overlays around the toebox and heel provided much-needed protection on rockier trails. After getting wet, it drained and dried out incredibly fast.

The gusseted tongue was as cozy as it was minimal. The padding, present only in the center, kept the laces from cutting into my feet. The toe box gave plenty of room, allowing my toes to spread out, which was key in my longer runs when my dogs would start to swell.

The ride was on the firmer, snappier side, which is exactly what I’m looking for when running off-road. The top layer of responsive Aecore Ultra foam worked in tandem with the Pebax plate below to provide great energy return and a fast transition on lift-off. The Aecore Plus supercritical EVA below the plate gave much-needed support and shock absorption. Paired with an 8mm drop, it felt as responsive as it was fast. I found myself landing on my midfoot, and as my feet lifted off, I naturally propelled forward using the balls of my feet.

The Vibram MegaGrip was top-notch, providing exceptional traction. I didn’t have the pleasure of trudging through ice and snow like John, but I did take it through an array of mud, slop, stream crossings, and rocks. They performed well above my expectations. I never slipped in wet conditions and had adequate protection from rocks and roots. When I took them on the pavement to connect to different trails, I never felt like I was tripping over myself from too much tread.

What we don’t like about the Mammut Aenergy Trail Endurance Ultra

JOHN: My only real complaint about this shoe is the sizing. I normally run in a US M11.5, but I received a UK 10. Normally, I wouldn’t have gotten that size, but the US M11-equivalent worked well. This isn’t exactly something I didn’t like, but something you may encounter with this shoe. Just be mindful that the sizing runs a little differently than most shoes I review.

This may sound really shallow, but here goes. Are we sure the Mammut Aenergy Trail Endurance Ultra is a good name? Couldn’t we have done better, Mammut? People on the trail were asking me what I was wearing, and I’m not gonna lie, I struggled getting all that out! I just said Mammut, and most people were like, “Oh man, they’re making shoes now?” So there’s absolutely interest, but that name is really brutal to bring up in conversation. Also confusing if people want to find out about it. Maybe I’m off base here, but couldn’t we have made that easier, Mammut? Could we?

JON: I will say that the price is up there, but this came as no surprise. Mammut is on the same tier of brands as Arc’teryx and Salomon. The silver lining is that this shoe will last you a very long time, so it’s worth it. Thankfully, the other issues I had were fixable.

While the lacing system provides good midfoot support, it didn’t deliver a locked-down fit in the heel. I found my ankle rolling a little bit at times, especially when tired. I used a runner’s loop, which thankfully provided added support for my ankle.

Next, this shoe will take a little longer to break in. When I first got it, everything was way too stiff. Thankfully, this went away after about 20 miles. I wouldn’t necessarily say this is a bad thing, though, as it speaks to its longevity.

Lastly, Mammut is a European brand, so the sizing was a little off for my American feet. I normally wear a US M13, but I was sent a US M12 at first, and they didn’t work at all. I can fit into a 12.5 at times, but a full size down was way too tight. I’m glad I ended up getting the right size.

Final thoughts on the Mammut Aenergy Trail Endurance Ultra

JOHN: This shoe is not a faker. It’s not some dude who buys expensive outdoor gear to wear to look cool in a coffee shop. It’s Daniel Plainciew in There Will Be Blood. Yes, it drinks the trails milkshake. It drinks it up. It loves sloppy, awful conditions and lives there rent-free in those places’ heads. It scares hard race courses. It makes them run!

Yes, the sizing is kind of tricky, and it may take some careful testing to get the right size. I was lucky mine just happened to fit, but when you dial in this shoe, it absolutely rocks. I’m taking it for at least a loop at The Wild Oak Trail 100 next week, that’s how much I like it. I ran a 100k in the shoe and still want to run at least another 28 miles in it!

Bravo to Mammut, this is a tough shoe ready for the hard stuff. I didn’t see this coming! I know it’s early, but I’ve reviewed a lot of shoes this year, and so far this is my favorite. It did an incredible job keeping me safe out there. And that in itself is a full-time job, let me tell you!

Update: We had to sit on this review for a while because sizing was off for a few of the other reviewers. In the meantime, I put in another 26 mountain miles at the Chocolate Bunny, on top of the DUC 100K earlier this year.

This shoe is tough. The only real knock is the sizing; just be careful dialing that in. Once you do, though, it performs. I ran it through freezing, wet, snowy flat trails and highly technical mountain terrain, and it handled everything.

It’s genuinely a joy to run in. I want to give it an A, but a B feels fair because of the sizing. And honestly, that’s not even terrible—I questioned mine at first, but it turned out to work great. No blisters after multiple runs, and I definitely beat the hell out of it across all kinds of trail conditions.

JON: This was a home run for me. I was skeptical at first, but I am a huge fan and am excited to see what else Mammut has on the horizon for trail running. Jump on the Aenergy train before the hype beasts do.

You can pick up the Mammut Aenergy Trail Endurance Ultra for $199 from Mammut by using the buttons below.