After establishing itself as one of the best marathon racing options on the market for the past several years, the Saucony Endorphin Pro series is showing no signs of slowing down with the introduction of its 4th iteration. The Endorphin Pro 4 keeps everything runners love about the series while making upgrades in key areas to elevate its performance even more. The biggest upgrade seen in the Endorphin Pro 4 is the addition of PWRRUN HG cushioning in the top layer of the midsole. This highly responsive and lightweight foam compound is also found in Saucony's pinnacle race day shoe, the Endorphin Elite, and helps to deliver an even more energetic underfoot experience. The layer of PWRRUN HG sits within a carrier of PWRRUN PB cushioning that helps to stabilize the softer foam and add durability. Meanwhile, a carbon plated is embedded between the two layers of foam, working in conjunction with the SPEEDROLL geometry to deliver silky smooth transitions and a highly efficient ride from start to finish. In the outsole, the lattice designed rubber in the forefoot is combined with strategic rubber placements in the heel. This assures a low overall weight of the shoe without losing the traction needed for fast turns. The Endorphin Speed 4 is wrapped up with a minimal, yet secure, upper that is refined with small, but noticeable, improvements throughout. In particular, the integrated tongue not only offers a more streamlined fit, but delivers extreme comfort and an amazing lock-down. All in all, the Saucony Endorphin Pro 4 represents another leap forward for the brand and looks to cement itself as one of the best marathon racing shoes money can buy.