Let me get something out of the way before I jump into my review.
I'm not a minimalist runner. I am a solid mid-foot striker and have been for about a year and a half. I moved to a mid-foot strike after dealing with ITBS when nothing else worked. I tried the whole 'minimalist' thing after reading Born to Run, but realized it didn't work for me as a trail runner; I needed more between me and the ground. I respect those guys who hold on tight to that concept; if it works for them then that's great. But I personally don't have a place for it in my running style. That being said, I am a big advocate of a mid-foot strike and wearing shoes that promote that.
THE ALTRA INSTINCT IS NOT A MINIMALIST SHOE. You may have read other reviews from minimalist runners who will talk heavily about their minimalist style and where this shoe fits into that methodology. Like I said above, that's cool for them and if this shoes has a place in their training and racing, all the better. But I feel it's important to suppress any incorrect assumptions. This shoe is so much more than a minimalist shoe that to corral it into a single genre of running would not do it justice. Altra has a minimalist shoe, but that is forth-coming.
Here's the real scoop on the shoe and then the real deal on how it will work for any runner out there.
First, and this is the biggie, there is no drop from heel to toe. Yep, Zero Drop. Altra owns the term and it's well deserved. This shoe is created to promote good running form, nothing more nothing less. If you want to call that 'minimalist' fine, but really they are just promoting proper running technique that will help any runner become better, reduce injury, and learn a greater love for the sport and the benefits it provides.
Second, the foot bed is actually patterned after the shape of your foot. It's weird how it actually took an innovative shoe company from Provo, UT to come up with a shoe concept that people have been speculating about for 50 years. The widened toe box will allow your toes to splay evenly as the foot rolls over the toe and kicks back. Yep, no more blisters. And the cupping heel shape will hold your foot in place, even on downhills. You don't need to oversize your shoes by a full size any more.
Third, this is a soft shoe with a non-EVA midsole, so there is less to break down over time. The cushioning is responsive and will stay that way. If at any time you feel that the cushioning is failing in this shoe it is most likely due to the insole breaking down and not the midsole. You can get many more miles out of this shoe (and any shoe for that matter) if you'll simply replace the insole every 200 miles.
Finally, this shoe is light and flexible. It will perform equally as well for a runner going after a half marathon PR as well as an ultra runner pushing 100 miles. It's been tested in every type of racing and the results are the same - Brilliant!
Matt Williams running a rocky trail in the Altra Instincts
So now down to what it will do for you.
Because the heel isn't raised up you have no choice but to push your hips forward, straighten your back, and land softer on the middle to front of your foot. Technique problems? Solved. OK, it's not that simple, but it sure does help. For a runner trying to transition they will find this makes the process easier and more comfortable. For an existing mid-foot striker it will be like running on a cloud and only enhance your existing form.
In the process of transitioning from a heel to mid-foot strike every runner goes through certain 'pains'. These commonly include calf and achilles pain. For those who push too hard too soon they may even encounter shin splints and pulled tendons. Altra is smart enough to tell you to take it slow and make the transition over time. Your body needs to get stronger, just like when you first started running.
However, making the transition in a pair of Altra Instincts is vastly different then the often tried dive right into a pair of Vibram Five Fingers or failing in an attempt to do it in a pair of regular shoes. While the move to a mid-foot strike is still adding more strain to your calves and achilles, the Instinct's10mm of cushioning between your foot and the ground significantly reduces the impact to both of those areas. As a current mid-foot striker I can say that I have had zero calf and achilles pain while wearing these shoes, but I still get it if I wear a pair of minimalist (less padding between my foot and the ground) shoes.
Like I said, this is not a minimalist shoe. It is, however, the most comfortable and form-promoting shoe I've ever put on my foot. I've worn it for dozens of miles on both the trails and roads. This shoe has seen mud, rocks, concrete, and asphalt and it has exceeded my expectations in every form of foot travel. All I can really say is, if the Instinct is this good I can't wait to see what the Lone Peaks can do in the dirt! I believe in these guys' philosophy and respect what they trying to do. I'm not a sponsored runner, I paid for my shoes like everyone else, but these guys have me sold for life. They live what they preach and I'm fairly certain they are going to change the face of running shoes.
And p.s., if you are a minimalist and want a minimalist shoe that will be everything and more try the Altra Adam. It will blow your mind.