I was wondering if any of you sports physiology experts and/or avid VFF wearers could help me out on this. I have been wearing my KSO Treks for beach sprinting and I love the feel of it. But I keep getting a sore achilles tendon on my right foot. Not bad enough to be debilitating, just uncomfortable.

What I can't figure out is why is it only on one side. I am careful to run the same stretch of beach sand in sets back and forth so that any slight tilt of the terrain toward the water would get evened out by going both directions.

I've been wearing both the treks and a pair of classics for a while now and so my feet are pretty used to them. I even wear them on 10 mile trail hikes with no problems. It's only when I sprint that this hurts.

Any thoughts or suggestions would be appreciated.

Robin