On footwear - again, CONTEXT is King.

As many of you know, the topic of appropriate kettlebell training footwear has been discussed exhaustively, on blogs, at RKCs, in books, on the forums.
The standard is: Barefoot, or a thin, flat, hard sole. Nothing cushy.
[If you are not yet familiar with the reasons for this, the primary reasons are: 1) Rooting and 2) Activation (as opposed to suppression) of mechanoreceptors.]

Until today, I had considered the Nike Frees to be an acceptable choice... and then I thought about it. The Nike Free is designed to: more closely resemble the mechanics of barefoot running, as compared to that with traditional running shoes. (The 5.0 is considered a half-way compromise.)

And the keyword there is: RUNNING!

The reason the Free falls into the "barefoot" shoe category is the deeply waffle-cut sole, which allows the shoe's sole to bend and flex with the foot, as it rolls through its ground contact with each stride.
What's important to note, is that there IS no such motion involved in kettlebell training. We don't, ever, roll from our heels and push off our toes. We stay ROOTED through our heels, always connected with the ground.

The Frees still have cushioning. It's simply a flexible cushion. It is still designed to soften the impact of runners' heel strikes (which, by the way, turns out to be a self-fulfulling prophecy - buy a shoe to "soften" the impact, and you end up striking harder! And the "requirement" for the cushion is reinforced...Brilliant. See the article linked below, for additional information on this.)

Of course, in the context of kettlebell training, that "flexible cushion" feature is completely wasted. Cushion the heel? That's the opposite of what we want in kettlebell training! Stay rooted! Tension from the ground up. STRENGTH from the ground up. Can you shoot a canon from a canoe???

Hardstyle Kettlebell Training:
Zero impact.
Strengthen joints, rather than pound on them and weaken them.
Become more in-tune with your body.
Superior cardiovascular conditioning. In 2 minutes, you know it.
Balance of anterior and posterior muscle chains, stabilizers along with movers: nothing is over- or under-developed (common to runners and traditional weight-training, and yes - this leads to injury).
The carryover to every other movement and/or performance and strength-based activity is second-to-NONE.

And by the way, just because a trainer has you using a kettlebell - remember that it's just a weight. It's just a tool. Nothing more. EVERYTHING depends on how it's used. I see a LOT of people performing bad movement with a kettlebell. It's not the kettlebell that makes training good (safe, effective), it's the movement. A kettlebell simply allows the perfect execution of movement, with an added load. Please be aware of the difference!

So I went off-course for a moment, but the conclusion is: the Frees are officially off my "ok" list.

(Still on the list: Vivo Barefoots, Vibram Five Fingers, Chuck Taylor Converse, others upon inspection)

And here is another recent article regarding the problem with running shoes (thanks for sharing it, Brett).