I was channel-surfing and happened upon Extra promoting a segment with Dr. Oz. He was talking about flip-flops, and he was talking about their dangers.
On the show, he was saying that the problem was that, without a heel, the flip-flops would stretch your tendons too much. (Of course, while flip-flops are not barefoot, the comments he made apply to walking barefoot, too.) This is just silly.
When you wear a shoe with a heel your Achilles tendon is not being used and stretched the way it is supposed to. In particular, high-heels are awful for leading to a shortened Achilles tendon, and can lead to Achilles tendonitis, as noted here.
Women, who are frequent wearers of high heels that take up physical activities such as running, can be prone to Achilles tendonitis. This is because the Achilles tendon is shortened by constant wearing of high heels, therefore when flat shoes such as trainers are worn, the tendon becomes stretched and inflamed.
The solution is not to eschew flip-flops or bare feet; the solution is to use your feet properly and not let the Achilles tendon get shortened. If somebody who always takes the elevator huffs and puffs and nearly faints when taking stairs, you don’t advise them that maybe they could use an escalator instead. You advice them that maybe they ought to get some real exercise and get into shape.
Dr Oz said many podiatrists consider flip flops to be the most dangerous shoes we wear. Flip Flops are potentially even more dangerous than stiletto heels! The problem is that under the bone in the arch of your foot is a thick connective tissue called the Plantar Fascia, which runs from the heel of your foot to your toes. When you step and put weight on your foot, if there is no arch support, you can get tears in your Plantar Fascia that do not heal since there is not a lot of blood supply in that area. These tears in your Plantar Fascia can cause sharp pain in your ankles and feet in the morning when you get out of bed. However, you can get Flip Flops with better arch support and a bit of elevation in your heel. I think the flip flops Dr Oz showed were called FitFlops.
Again, a gentle stretching of the tendon that has been artificially shortened by heel-wearing would be a better solution, not advice that just perpetuates the deformity. Also note the continued propagation of the idea that feet somehow need “support.” They only need support because shoe-wearing weakens all the muscles, ligaments, and tendons of the foot. If you use your feet properly, the arch gets to work the way it is supposed to.
I guess we should not be surprised to discover that, in the end, a footwear product is touted: flip-flops with a heel and “support.”