There aren’t any surprises in this update; if you liked previous versions of the Instinct, this will continue to be a favorite. The 3.5 is one of the few zero-drop options on the market, and probably one of the best for high mileage road training. It is also one of the most comfortable all-around shoes in our test group, but lacks a bit of zip and spring when it comes to speedwork or racing.
Altra stakes its reputation on zero-drop footwear that allows natural movement of the foot while providing a protected and comfortable ride. The Instinct 3.5 is stocked with many of the company’s standard technologies and design elements that have earned a loyal following over the years.
Fit The Instinct 3.5 is true to size, and the anatomic last matches most foot shapes very well. Some testers find Altra shoes wide through the midfoot, but the classic lace mechanism cinches the upper securely to the foot. Moderate padding on the tongue and ankle collar improve comfort as well as securing the fit.
Comfort The rounded toe box is ideal for allowing full toe splay on impact and virtually eliminating any problems due to toes rubbing on each other. It also has good vertical clearance to prevent friction on the top side. Padding is soft and comfortable around the heel and midfoot, and the cushioning underfoot minimizes ground impact.
Responsiveness Altra tinkers with its A-Bound energy return EVA midsole compound from time to time, and this new version earned mixed reviews from our testers. Some found the ride pleasantly springy, but others felt that its increased softness lost some energy transfer from heel to toe. This concern is probably more pertinent for heel strikers, while midfoot strikers should experience a nice rebound from the midsole. Outsole rubber is prominent in all of the impact areas underfoot, but the flat and shallow configuration loses some grip in slick conditions.
Ride Quality FootPod technology in the midsole and outsole aligns flex areas of the shoe with the bones and tendons of the foot, which provides natural flexibility and a smooth transition through the step cycle. This is another category where midfoot strikers will benefit more than heel strikers, who might feel some overall sluggishness.
Speed Relatively light weight and a secure fit make the Instinct 3.5 well suited for speed training in dry conditions, but the midsole material doesn’t allow quick leg turnover as effectively as other models in our testing. This is more of a marathon model than a 5K racer.