Warning - do not run in Altras if you have &#34;narrow Achilles&#34;, which apparently I have. For some reason, they haven't solved the structural issue of accommodating for people with narrow feet, so wearing these was like a horrible flashback to days as a kid when I was forced to wear boots instead of flip flops on trail hikes. They slide around in the back despite fitting well throughout the rest of the shoe. A great shame since I love zero drop shoes and they are so hard to come by in the running world. Good luck shoe shoppers of America!