The human foot is an amazing shock absorber and the idea of running barefoot isn't crazy if you want to run faster. A stronger, more supple foot and ankle will allow a runner to race faster. In my search to find a way to strengthen my feet to withstand the rigors of running ultra marathons I came to barefoot running over four years ago. I started slow running barefoot for 5mins every other day and built up to being able to run 90mins straight over a period of two years.

 What I found over time, with my feet getting stronger, I started using racing flats as my main training shoe. The problem was, the more I was using minimalist shoes, the more fatigued my feet were becoming to the point where I was not recovering between training session and up to last week when I switched to regular cushioned shoes I even had to skip workouts as my feet were just too tired from the previous workout.

 Basically though my strengthening I kept reducing my shoes to lighter and lighter shoes with less and less cushioning which was great through the summer as I run on grass but through the winter I was on the paved bike paths and the pounding was building in my feet so when I switched to regular cushioning shoes the extra cushioning allowed my legs to recover faster and allowed me to train more.

 Running barefoot and in minimalist shoes is great but I think there is a balance. Through barefoot running, maybe 3% to 5% of your weekly mileage, I think you can move yourself from a stability shoe to a neutral shoe over a period or 8 to 16 months. Which ultimately is the best thing for your foot and then from there you can add options by wearing a cushioning shoe for your core mileage, a light weight trainer for your tempo runs and possibly a racing flat for your fast intervals and races, while maintaining your 3% to 5% of barefoot running. The same will hold true for trail shoes.

 My suggestion would be, from my experience, use a cushioning shoe though the winter, as you will be on pavement and will not have access to soft grass, this will reduce the pounding and allow you to recover between training sessions. The same would hold true in the summer if you do most of your mileage on pavement. If you run predominately on grass though the summer then you can receive the cushioning through the softness of the grass and use a more minimalist shoe. Your choice of shoe will depend some what on the terrain you choose to run on.

 I have been running a little under a 80km's a week and I run two or three times a week on squishy sport-turf, treadmill or with the snow melting on soft grass barefoot. That only adds up to three percent of my weekly running volume and in terms of the Nike Frees, I do not run in them much anymore but I do a ton of drills in the Frees and probably spend an hour or two a week in those shoes.

 My point is that if you're running 30-40 miles a week and wanted to run the same percentage of your weekly volume barefoot as myself, a strong promoter of barefoot running, then that is just one mile a week, broken up into 800m one day and 800m another day. So if you think it's something to add to your training program avoid the temptation to go out and run five or six miles a week barefoot, it may lead to an injury. Take it slow and allow your body time to adjust and over time your feet will gain strength, your stride will improve and you will be able to withstand more training without breaking down. After a period of time maybe you can look at increasing the amount of barefoot running you do, but I would only suggest doing this on soft grass.

 Through my own experimentation I can midfoot strike just as easily in a cushion shoe as I can in a lightweight trainer or racing flat, for me it is more a issue of correct pelvic position and core strength that allows me to midfoot strike and not necessarily the height of my sole on my shoe, but that only relates to myself, everyone has had different experiences adapting a midfoot strike.