At most I would use them occasionally to "mix it up", but your body needs the support that a well built shoe provides more than any advantage the Nike Frees may give. An example, I have a patient who runs 120 miles per week. If he decides to use the Frees during an event, he will train with them 1 day per week for 4-6 weeks prior. ust enough to get a feel for them, but his body breaks down if he uses them any more than that.