Have you operated vibrating machinery for long periods? There is a condition popularly called 'white finger disease' This was first observed in chain saw operators. Vibration stops blood flow in the capillaries and eventual collapse. Poor circulation, sensation and sensitivity to cold are symptoms. My personal system are poly or smartwool glove liners for neded quick duties requiring dexterity ( and you won't freeze your hands to cold objects- BTDT!) Dachstein boiled wool mittens ( www.campmor.com) and a shell guantlet. Oh, and lots of snack food to keep my internal furnace going.