I regularly do a four week endurance programme based on morning run and evening gym session. The gym work includes alternate days upper body and legs. In my local gym, they have a reasonable selection of free weights and machines, and it´s not too busy so you can do rapid circuits without being held up by iron pumping posers. However, I have always been told that free weights are better for you than machines, but if you´re doing circuits, you can´t always keep your weight set up reserved for 30 mins, and you can´t always get someone to spot for you. So I usually end up using the the shoulder press machine and bench press machine for those exercises, the rest being floor exercises or bicep curls with dumb bells. My question is, which is best for you, free weights or machines?