If the foot is too weak, it is not stable but too mobile. The excessive mobility in the foot causes a compensation in the ankle. The ankle then gets "stiff" but in an unhealthy way. The ankle being too stiff then requires the knee to shift towards more mobility. The knee does NOT like mobility! The knee is a hinge joint and likes to move in one line. In its optimal line, the knee is very happy. Push it out of alignment, and your ACL, meniscus, etc. will start barking at you or even fail. There seems to be an increasing amount of ACL injuries going around. I'm seeing these concerns in my research journals and other health/fitness postings. Why? Our shoes are at least part of the reason! There is a new book a lot of people in my business are reading and talking about called "Born to Run." The book examines many aspects of ultrarunning but the most amazing one is a tribe in Mexico that has been running hundreds of miles WELL for generations with NO SHOES and without all the "Western" injuries we see in cultures that wear shoes! There is a theory now that conditions like plantar fasciitis, ACL injuries, meniscus injuries, etc. many times are being caused by our shoes that weaken the biomechanical structure of our feet! Let's think about this SIMPLY...if you're running with a fancy air-sole running shoe, you're probably doing a heel-toe strike (unless you're a Chi Runner). If you tried to run heel strike first barefoot, you'd break your foot! So essentially, our "modern" shoes have completely changed the way we've been running for generations. When people run barefoot, they strike on the mid foot for the most part. Your mid foot is where the suspension system is--your "arch." The arch of your foot is spring loaded--it can absorb the foot strike shock. The heel's ability to absorb shock? NOT! You've got a little skin and very thin fat pad then your calcaneous bone underneath. Hit the heel first and you'll get way more shock up your leg into your back. Strike on the mid foot and you'll be absorbing the shock the way the foot is supposed to absorb it. Pretty cool isn't it?!!!
Basically--our shoes are made too well and make our feet weak and lazy. Everything up the kinetic chain from our weakened bases of support (feet) are then compromised. Again, I'm fascinated with all this talk on foot fitness!
Fellow RKC Kettlebell Instructor and author of "The Four Hour Work Week" Tim Ferriss put up a GREAT post and video on the Vibram Five Fingers. It's an absolute must if you're interested in what I explained above. Here's the link:
- Born To Run (Book Notes Video Book Review)