I'm 68 and have been running off and on for years - 2:30+ marathon and 4+ min. mile, many years ago. Now I live in a warm climate and run about 2 miles every morning, sometimes up to 5 miles. Run a couple of 10k's during the year - in about 46 minutes. I have been using Nike Free 3.0 for about a year and love them but I have -- for the first time ever -- developed an achilles strain. Hasn't got any worse, but it is a nagging concern. I have rested a bit and it gets better, but is still hanging around. Someone suggested it might be the shoe -- either the minimal heel to toe drop, or according to one friend, the fact that those shoes actually lead some runners to overpronate. I weigh about 185 and could stand to lose 10 lbs., so maybe that contributes to it. I am looking for suggestions for a new shoe to see if that helps. I tried the Lunarglide 6 and felt like I was in clodhoppers. I love the lightness and soft feel of the Nike Free and was wondering if switching to the 4.0 or 5.0 and their higher heel to toe drop would help. Thanks in advance for any tips!