They’re Ugly, Unproven, the Stuff of Hippies, Tech Bros, and Runners. I Tried Them—and Was Surprised by What I Found.
I pressed my left big toe down on a credit card–sized rectangle, trying to use only the digit and not any other part of my body, so as not to interfere with the test that promised to tell me my toe strength. The woman in front of me, an employee of the …