Recently bought Xero shoes, the Prio Neos, my first ever minimalist shoe, to try this all out after reading "Born to Run". So I run about 3-4 times a week in typical running sneakers, and tried running 2 miles in the Xeros...it was a big adjustment and made me aware how I was still heel striking. Then ran 5 miles in the Xeros, adjusted my form, no problem. But my last two runs, 6 and 4.4 miles in the Xeros (all on pavement) have felt like "the breaking-in period". My calves are so achey and my ankles are so tired right after, and it is taking me a day to recover and feel back to normal.
I read the Xero website about the reasons for the initial sore calves and overworking the muscles, but I'd still like to hear how other runner's breaking-in period has gone and what you did? With the new soreness, did you run less, or rest more, or alternate sneakers etc.?