This is bizzare !! I thought I was the only one who suffered this. I tried everything, at least 3 different physios, an osteopath but no one could cure it long-term. Now it seems to have dissapeared of its own accord. My numbness used to hit on exactly the hour mark and then gradually dissapear over the following 10 minutes. Sometimes it used to be the whole lower left leg (never the right side). Its the funniest feeling, running on "one leg" for 10 minutes. The laces trick is an interesting one and the stretches sound useful.