I have a problem with the middle toes of my left foot going numb, both while running and cycling. The only thing I've found that helps is to wear the laces very, very loose over the highest part of my foot. Any pressure there, and my middle toes will soon be numb. In my efforts to figure this out, at one point I bought some inserts recommended by my running store. I took off for a 4 mile run; by 2 miles, both feet felt numb and tingly (and not in a good way!), and I still had to get back home! Argh! Good luck to you. It can be so many things--for me, overly tight laces are unbearable.