Updates to Aku Alterra GTX

  • Aku designed the Alterra GTX to overcome challenging terrain with its beefed-up technologies. ELICA - Natural Stride System is the integration of features from the last down to the outsole (Vibram Octopus) that aims to deliver a more efficient and comfy ride. The custom fit IMS footbed further enhances shock absorption.
  • The Internal Midsole System (IMS) is partnered with the Exoskeleton technology to provide protection and support right where they are needed. It also guarantees a safer stride on mixed terrains.
  • The upper is protected by the Liba Smart PU overlays which are lightweight and durable. It also maintains the structural integrity of the pair. The combination of eyelets—from webbings to pulleys—lessens the force required to customize the fit.

Size and fit

The Alterra GTX caters to male and female backpackers. This boot is offered in standard width. It comes in regular lengths which generally run true to size. Using the Aku last, this footwear replicates the anatomy of the foot including the sculpture of the arch. This design enables this backpacking boot to follow the natural biomechanics of the foot.

From the Aku last, some adaptations have been made to further benefit the user depending on the terrain. Alterra GTX has the Woman Fit for females and the Anatomical Fit for males. Both are customized to provide stability and comfort on uneven grounds.

The lacing setup of the Aku Alterra GTX uses a combination of eyelets for an optimal and secure fit. At the toe end is a webbing eyelet followed by three sets of rotating pulleys. With a single pull, the pressure is evenly distributed all the way down to the toe. The heel area has a webbing loop and completing the lacing system is a dual pair of metal hooks.


The boot has a Vibram Octopus for an outsole. Aku also uses the ELICA technology in constructing the design of the outsole to ensure that it follows the asymmetrical composition of the midsole. The lugs on the medial forefoot are oversized to increase the propulsion area. They are also projected outwards to maximize grip and stability. Moreover, the rubber on the heel is wider to increase contact with the ground.


The Internal Midsole System (IMS) for trekking is partnered with the Exoskeleton technology. The latter is applied to the sole. This architecture aims to provide protection and stability where it is needed. A light PU is applied to the external skeleton of the midsole which goes up to the rear adjacent to the heel. Its asymmetrical design includes a wider and higher PU in the medial area to support and control pronation.

The insole board of Aku is constructed with their concept of the Internal Midsole System (IMS). It is a technology that adds a layer of microporous material to the lasting board which allows the sole to adapt to the contours of the foot. The lasting board renders medium stiffness with its nylon and die cut EVA. Like the Aku last, they are designed to mimic the natural inclination of the forefoot and heel. During stride, IMS promotes even distribution of pressure while it prevents slippage inside the boots. It is also shock absorbent which guarantees a more comfortable ride.

As part of the ELICA - Natural Stride System a proprietary technology from Aku, the midsole of the Alterra GTX is constructed using dual density PU. The softer PU is mainly designed for cushioning and protection. Its lateral side has a thicker PU material to be more shock absorbent on landing while the softer material on the propulsion area helps dispense the force during toe-offs. On the other hand, the harder PU is for support and stability. It goes into the arch area and renders a right amount of support. Likewise, its medial side is thicker to be extra helpful during heel strike. This system reduces fatigue and strain.

The Aku Alterra GTX uses a breathable custom fit IMS footbed. This material dries quickly and has thermo-insulation. Moreover, it renders anatomic support and is shock absorbent.


Hugging the top of the foot is suede and stretch fabric upper. This is lined with the Gore-Tex Performance Comfort laminate which takes care of the waterproofness while offering a convenient level of breathability. It has moderate insulation to be able to adapt to a wider range of outdoor conditions.

With an elastic tongue, this high-cut backpacking boot is able to cradle the foot more comfortably. It is constructed without a gusset, but it does not trade-off the safety against debris and splashes of water. The padded ankle cuff is also designed using a stretchy material that renders additional comfort. Furthermore, it enables a non-restrictive movement of the ankles.

The lightweight Liba Smart PU gives protection and structure on the upper of the Alterra GTX. This material is known in many industries due to its robustness and abrasion resistance. Moreover, it works well in a variety of weather conditions and is environment-friendly. The sturdy heel cup and toe box provide additional protection, too.

Nice to know

  • The Backpacker magazine acknowledged the Aku Alterra GTX as Best Fit model in test.

Facts / Specs

Weight: Men 23.6oz / Women 19.4oz
Use: Backpacking
Cut: High cut
Features: Orthotic friendly / Removable insole
Waterproofing: Waterproof
Width: Normal
BRAND Brand: Aku

Compare popularity Interactive

Compare the popularity of another shoe to Aku Alterra GTX:
Paul Ronto
Paul Ronto

Over the past 20 years, Paul has climbed, hiked, and ran all over the world. He has summited peaks throughout the Americas, trekked through Africa, and tested his endurance in 24-hour trail races as well as 6 marathons. On average, he runs 30-50 miles a week in the foothills of Northern Colorado. His research is regularly cited in The New York Times, Washington Post, National Geographic, etc. On top of this, Paul is leading the running shoe lab where he cuts shoes apart and analyses every detail of the shoes that you might buy.