The Keen WK400. Photo: Bob Smith/grough

Price: £135
Weight: 774g a pair
Country of manufacture: Cambodia
Uppers: synthetic fabric
Waterproofing: none
Women’s version: yes
Sizes: men’s ; women’s
Sole stiffness: 6/10

The WK400 is, Keen says, the brand’s revolutionary shoe designed to make walking more enjoyable and fun.

It says the shoe has taken three years to develop, with more than 5,000 miles of testing.

The concept began when Keen’s global product innovation creative director Rory Fuerst Jr had a traumatic skiing accident that left him unable to walk.

A Keen spokesperson said: “Along his road to recovery, he found himself depressed and in a deep fog.

“As an accomplished athlete he never considered walking important, but four months into his recovery he discovered walking was much more than a means to get around. Walking brought him out of his fog and saved his life.

“This experience inspired him to share the power of walking with the world and has served as the catalyst for Keen’s latest innovation, one that is revolutionising walking footwear.”

Fuerst enlisted the help of his long-time friend and footwear innovator Ciro Fusco, who has a doctorate in physics and environmental science, to examine the science of walking.

The Keen WK400 is the result of a great deal of research. Photo: Bob Smith/grough

Keen said, in biomechanical lab studies, it discovered that the body and legs act as a pendulum which cause the foot to move in a constant arc when walking — a pattern that is different from a runner’s stride, which is more like a spring loading — and one that existing shoes fail to facilitate.

So the brand came up with its patent-pending Keen.Curve system. “This technology combines constant curve geometry, underfoot plate technology, and a high-energy midsole to create a unique feeling of forward momentum that makes walking feel like rolling,” it said. “Additionally, a generous 30mm toe spring gives an exceptionally smooth and easy transition from heel strike through to toe off, making every step feel easier. A 10mm last drop between the heel and forefoot further promotes forward momentum in your gait, while also aiding stability.”

So, being a bit of a fan of walking myself, it seemed only right to try out a pair of WK400s.

The shoe is lightweight and the upper is made from sturdy-feeling fabric, with extra reinforcement at the toe and heel area in the shape of plastic overlays. The whole uppers have small perforations for ventilation, with larger perforations at the forefoot, sides and heel. So this is a shoe for dry days when the ventilation will be welcome.

Though when there was an ingress from puddle splashes and wet mud, the shoes did dry out quite quickly.

The heel cup is stiffened and there’s a little toe protection though this isn’t substantial. There’s a good amount of foam padding around the ankle and there are webbing loops at the heel for helping to pull the shoes on.

Lacing is asymmetrical, with the lacing system angled to the outside of the foot.

But it’s the sole unit that marks this shoe out from the norm and which is at the heart of this walking innovation. As the name suggests, the shoe’s Keen.Curve sole has an obvious arc. The sole, including the midsole and outsole, forms a wedge shape, thickest in the centre, foot-arch section, less thick at the heel and thinnest at the forefoot.

There’s a 10mm drop between the heel and the forefoot, giving a forward impetus when on the move. In fact, standing still in the WK400s actually feels a little unstable, as the centre point of the shoe is the area in contact with the ground, with heel and toe both elevated a little. There’s a definite rocker tendency and the foot arch feels to have a large amount of support.

On the move, the shoe gave me a definite forward impetus, and my gait felt somewhat more upright than usual, perhaps to counter the perceived forward momentum of the shoes.

There’s also plenty of underfoot cushioning, with the initial heel strike absorbing much of the energy, then rocking the foot through the arch area to the forefoot. There’s 30mm of padding at the front of the foot so even at its thinnest point, the midsole and outsole provide a good amount of comfort.

Torsionally, for a lightweight fabric shoe, the WK400’s sole is surprisingly stiff, which meant it felt sure-footed on more technical terrain. Most of the flex is at the front of the shoe.

The sole unit of the new shoe. Photo: Bob Smith/grough

Take the well cushioned insole out of the shoe and you can feel there’s good stiffness in the midsole plate, so there’s no sloppiness in the Keen shoe’s stability.

One point to note is that there’s a marked heel protrusion, so a little care is needed to avoid catching this with the opposing foot in narrow terrain sections.

The outsole is a Keen unit, with fairly soft rubber lateral ridges at the heel and toe sections, and 4mm diamond and rectangular-shaped lugs, each of which has a little soft bobble on it. These are arranged in an arrow formation in the centre of the shoe. Grip on mud was good as was traction and braking on dry rock. Given the nature of the shoe, I didn’t test them on wet rock.

Warmth from the uppers was good without being over-hot, though the weather during testing was cool to cold. The thick sole gives good insulation from cold ground.

After a couple of hours walking in the new Keen shoes, it was evident my muscle use was slightly different from that while wearing conventional walking shoes – a result I presume from the more upright posture they induced, along with the rolling action of the foot with the terrain.

Keen is wrapping today’s launch of the WK400 in a wider campaign to encourage people to walk and reap the benefits not only of the physical activity involved, but the emotional and mental wellbeing that a happy walking experience can provide.

It said: “Keen is on a mission to establish walking as a movement, focusing on raising awareness around walking clubs, charities, as well as debuting their very own walking-focused podcast.”

The WK400 is certainly an interesting development, aimed firmly at walkers rather than being an offshoot of a running model. I’ll be using future dry periods to further test the shoes and evaluate them over some good long-distance routes. If Keen can come up with a waterproof version, they could be onto a winner with endurance walkers.

Pre-launch information on the shoes’ sustainability was scant, but Keen has a good track record in responsible trading. It recycles a variety of materials into its footwear, including coffee-ben sacks and paraglider fabric. It is pioneering the use of plant based ingredients in its polyurethane soles and makes use of recycled PET bottles in its footwear. Some of its products contain 50 per cent recycled wool.

The Keen WK400 is rated a good buy. Photo: Bob Smith/grough

It supports minority groups in accessing the outdoors in Oregon and its employees have been given time off work to take part in litter clean ups in the outdoors. It has taken PFCs out of products that don’t need them and is switching to PFC-free treatments to its waterproof footwear.

Keen has also provided financial support to tsunami relief and conservation projects as well as supplying 100,000 shoes to frontline workers. For sustainability, the company says it builds its products to last.

Best uses: dry-weather trekking; long-distance walking; country walking; trail walking; urban walking.

Performance 33/40
Comfort 27/30
Quality 8/10
Value for money 7/10
Sustainability 8/10
Total score: 83/100