I got into "natural running" a couple years ago after being sick of being injured all the time and dealing with shin splints, ITB syndrome, and a myriad of other problems. I started with a combination of straight barefoot running, and running in Vibram Fivefingers Bikila Shoe, and got a stress fracture after a couple months that kept me out of running for a year. I wish I had read Abshire's book first, because I could have avoided that problem.
The concept of natural running deals mainly with landing on your midfoot/forefoot when you strike the ground, rather than your heel. The first half of the book explains why a heel strike is bad, and why you should change your form. I run into a lot of resistance when I tell people I'm a barefoot runner, mostly from the belief that you need 2 inches of cushioning under your foot to prevent injury, and secondly that you need to protect the bottom of your feet. The book does an excellent job of debunking the first claim. I have run thousands of miles in shoes and was already committed to natural running before getting the book, however reading it just gave me a much better understanding of the practice and makes me more confident in my decision to move away from cushioned shoes. A lot of it I was familiar with and are the same old points (landing on your heel is effectively a braking motion, landing on your heel transfers all the impact of your weight to your knees, etc), but there is a lot of original stuff in this book too.
Once Abshire has convinced you that heel striking is bad, he then looks at proper natural running form. Getting rid of your traditional running shoes is one thing, but what many people who run barefoot or in minimalist shoes overlook, is that you also have to use proper form. This is critical for a successful transition and the main reason I got a stress fracture. Abshire discusses some of the main points, such as keeping your arms at 90 degrees, leaning your body forward to the point where you feel like you're about to fall over, and increasing your cadence (the amount of times your feet hit the ground).
The last part of the book provides a training plan for the complete beginner, along with form exercises designed to strengthen your feet and improve your form. Don't gloss over these! Although it may seem maddening to go from running 25-50 miles a week, to 2 miles a week, it is critical to start slowly to build up your feet, and more importantly, to make sure you are using proper form. If you get used to running with bad form you won't ever correct it. The first few weeks you start out you have to make a conscious effort to run with good form, and to always lean forward and increase your cadence. At first, it will seem like you are expending a ton of energy to do this and to turn your feet over so quickly, and it will feel anything but "natural," but after a couple months your body will get used to it and you won't even think about it. Most people should strive for a running stride of around 180 steps per minute, meaning your feet actually hit the ground 180 times in 60 seconds. The best way to do this is to download an mp3 of 180 beats per minute (search the Internet for "180 bpm mp3" and put it on a loop). This is one of the hardest aspects to get used to but one of the best for reducing injury. The book provides some great form drills for increasing foot strength. You may be tempted to skip these but if you don't have any other strength training plan for your feet, that would be a mistake. Years of wearing traditional shoes has made most people's feet weak and atrophied. Walk around barefoot every chance you get. If you need dressy shoes for your job, look into companies like Terra Plana that make minimalist shoes.
As a disclaimer, the author does sell his own minimalist shoes by his company, Newton Running. I have never worn his shoes, preferring the more natural feeling of my Vibram Fivefingers, but this fact may appear that he has an agenda. Even though he mentions his shoes a few times in the book, it never felt heavy-handed and it doesn't seem like he is trying to use the book to sell shoes. He is slightly critical of completely barefoot running and recommends against it unless using it for form practice on soft grass, but I would say he gives it a fair critique. His main problem with it is that same old idea that your are going to cut your foot or run over pebbles. While this is a possibility, it is not nearly as big a deal as people make it out to be. I live in an urban area and I have never cut my foot and almost never have a problem running on my city streets, especially once my feet got conditioned to the pavement and stopped being so sensitive. It even feels good to feel pebbles and different substances under my feet occasionally. But if you want a barefoot feel with some protection, try the Vibram line of shoes.
My one problem with the book is the author's training plan. I feel that it is way too advanced. His plan is 8 weeks long, but has you doing a 15 minute easy run by week 2. There is no way someone new to natural running should be doing 1.5 miles by their second week. In my opinion, you should spend around 5 weeks or more before you are up to that kind of mileage. I know that sounds crazy to people used to doing 20 mile long runs, but you are effectively re-learning how to run, and your feet will not be strong enough for that kind of mileage after just two weeks. If you want to be safe and avoid injury, take each of his weeks and repeat them three times. So you will spend 3 weeks on his "week 1," then move to his "week 2" and do that for three weeks. Or just gradually increase the increments you're running by 20% each week. Yes, this is a very slow way to do it, but it ensures more time to learn form and condition your feet. Below is my personal training plan I modified from his. Just replace his running days with mine and continue to do form and strength drills on off days. All my runs involve 5:00 walking warmup and 5:00 walking cool down:
Week 1
Tuesday - 10 min total - 100m (.07 miles) walk/run repeats
Thursday - 10 min 100m walk/run repeats
Saturday - 10 min 100m walk/run repeats
Week 2
Tuesday - 15 min 100m walk/150m run repeats
Thursday - 15 min 100m walk/150m run repeats
Saturday - 15 min 100m walk/150m run repeats
Week 3
Tuesday - 20 min 100m walk/250m run repeats
Thursday - 20 min 100m walk/250m run repeats
Saturday - 20 min 100m walk/250m run repeats
Week 4
Tuesday - 25 min 100m walk/250m run repeats
Thursday - 25 min 100m walk/250m run repeats
Saturday - 25 min 100m walk/250m run repeats
Week 5
Tuesday - 10 min easy run
Thursday - 25 min 100m walk/250m run repeats
Saturday - 10 min easy run
Week 6 (this is basically the same week as the book's week 2)
Tuesday - 15 min easy run
Thursday - 30 min 100m walk/.25 mile run repeats
Saturday - 15 min easy run
Week 7
Tuesday - 15 min easy run
Thursday - 30 min 100m walk/.25 mile run repeats
Saturday - 15 min easy run
Week 8 (Starting here, do the exact same program as week 3 in the book)
Tuesday - 20 min easy run
Thursday - 20 min easy run
Saturday - 20 min easy run
Week 9 - From here, just start with Week 4 from the book and follow Abshire's plan for the remaining 4 weeks. This will have you up to 45 minutes of running by the end of week 13, which I still feel is possibly moving a bit fast, so if you like, you can start with week 4 from the book here, and just do every week twice.
I feel like the above is a fairly conservative plan that will minimize the chance for injury while allowing your feet to get strong. If you combine it with the form and strength drills from the book, and go barefoot every chance you get, you should be in proper condition to start running seriously as a natural runner within 4 months. I know that sounds like a long time if you're currently a long distance runner, but the advantages you will get from it are worth the wait.
Update May 2012: If you're going to start running barefoot, I would suggest the Denco Easy Grip Professional Foot Smoother ~ Callus Shaver ~ w/Lifetime Warranty for taking care of your feet. I use it a couple times a week to keep my feet from looking like Christopher McDonald's and it is a great investment.
