The Saucony Endorphin Speed was launched as a fast training shoe, but quickly became established as one of the best running shoes and one of the most versatile, thanks to its comfortable, speedy ride. Given its popularity, Saucony has mainly stuck to a similar design with subsequent editions of the shoe, and that is still true of the Endorphin Speed 4.
There are updates to the shoe, though, and these have made the ride better at fast paces and improved its grip and fit. Picking up the Endorphin Speed 3 in a sale is still a good option, but the Endorphin Speed 4 is now the shoe to beat for runners looking for a versatile daily trainer.
