Good to know
- One of the biggest updates offered by the Instinct 4.0 is the removal of the stiff toe bumper. In its place is a more pliable one that creates more space and lessens the risks of irritations or blisters.
- Altra also created a significantly more breathable model in this shoe. The added holes all over the shoe makes it definitely more well-ventilated than the previous model.
- A more streamlined look gives it also a more sophisticated appeal that most runners have greatly appreciated.
- The outsole has more rubber for more grip and better cushioning.
- Finally, Altra lessened the foam in the tongue as it is not as bulbous as before, while the heel and ankle collar get more foam for a more plush feel.
Altra basically kept the fit and sizing of the previous model with the latest coming of the Instinct. The trademark FootShape last creates excellent room for the toes to splay. While the forefoot and toe box have ideal space, the heel and midfoot are adequately held in place. The sizing runs true. For those who have slightly wider feet, the generous forefoot space should be more than enough.
Altra’s FootShape outsole creates the premium opportunity for runners to have a more natural and flexible ride. The numerous flex grooves and the detailed outsole provide better shock attenuation and responsiveness. Also, with the thicker outsole, the rubber in the underfoot delivers long-lasting performance for the Instinct 4.0.
An injection molded EVA with Altra properties is called A-Bound midsole by Altra. It provides decent cushioning and responsiveness. The full-length construction enhances the movement through the gait cycle. The same midsole material is also found in the Altra Instinct 4.5.
An engineered mesh upper with more holes delivers a breathable and very supportive ride. The Altra Instinct 4.0 has decent flexibility and hold in the right areas for a secure, but natural movement. The upper shows minimal overlays (the logos only on both sides) to provide security. Only the right mix of flexibility and security hold the foot together for extended periods of time.