I’ve had this problem lately during my longer runs – my fingertips go numb. I really only notice after I finish and get that pins-and-needles feeling as the blood comes back to my hands.
After some research I’ve found that there are many reasons for numb fingertips, but mine seems to be the simple one – holding my arms up at a 90 degree angle for a long stretch restricts the flow of blood to my hands. When I’m done with my run, the blood starts flowing with more ease through my arms. The remedy for this is simple. Just put your arms down by your sides every so often while you run and shake them out for a few seconds. This will get the blood flowing again.
There are, however, a few more serious causes of numb fingers such as Reynauld’s Phenomenon, which is caused by changes in temperature or stress. Because this can be a sign of other illnesses, see your doctor if your fingers continue to go numb and white even if blood flow is good.