The Saucony Endorphin Speed 2 has become one of my top two marathon training shoes. I love the look, the fit and most importantly the energy return I get from my runs. Compared to the Endorphin Shifts (my previous training shoe), they are lighter and more responsive, although slightly less durable. I typically use the Speed for runs up to 13 miles, but for longer runs I switch to a softer, more durable training shoe. Mainly because they make me run faster than I normally aim for. I alternate 2…