i just finished a 1/2 marathon. I am 40 years old and ran it in 2:21. I took my pump off for the entire race and maintained a BGR of 140 throughout the entire race. I am afraid to take it off for the entire marathon in Janurary. Which will take 5 hrs i hope. i used hammer gel packets and cliff power blocks with great success, i just don’t want to stress my body out too much with out the pump. any suggestions? i have pushed myself in a number of things, but unlike a marathon, in those i could stop and check and make adjustments…..thanks