A matter of 1/4 inch

Couple weeks ago, when I used Shoe Goo to try to extend the life of my Nike Free, I noticed that the difference between the two sides of the right heel was around 1/4 inch. That difference has been affecting my form, which is not good. On my morning run a few days ago, I also got to thinking what that 1/4 inch actually meant, quantitatively. Now, with my normal training pace, which is about 1-1.5 minutes slower than my 5K/10K pace, I take about 200 paces each foot for each 1/4 mile or about 800 paces per mile. That works out to be, at my current weekly mileage, about 24,000 paces per week. That's about 6,000 inches or 500 ft. of extra vertical distance that side of the foot (Achilles tendon, calf) has to stretch each week! This got to be part of the reason my calves have not been their usual selves the past couple months. I suppose I should follow that rule of thumb of not putting more than 500 miles on a pair of running shoes!