Grade: 2
Developed shin splints on both legs just after crossing the 350 mile mark on my Asics. Worse on the left leg. Took four days off and picked up a new pair of shoes before they got too bad. Lots of icing helped.
Don't try to push through it. Retire any shoes on their upper mile limits and take a day or two off from running. Make sure to ice well after running until they're good and gone.