After reading a bit on this forum, I realized that my calf cramps are very similar to a lot of other barefoot runners’ calf cramps: they hit at about 1.6 km, always while I am running slightly uphill on paved road, and usually when I am pushing my speed a little. They are nasty cramps that force me to slow to a walk. Then all the shod people I just left in the dust come pounding past me! The knot in my calf stops me from running for about a week. Anyway, yesterday I ran just under 1.6 km and had no problem, but I want to be sure to rest long enough to prevent a cramp next time- I have a feeling these cramps may have something to do with fatigue from previous runs. Obviously, though, if I rest too long, I will lose whatever endurance I may have built up, and then the risk for cramping would increase, I guess. Any suggestions are most welcome. I am 1.75 m tall, about 90 kg and 50 years old. I do some gymnastics and other balance-related stuff, so I don’t think there’s a problem with my “core,” and I am reasonably flexible. I once ran about 6 km barefoot without cramping.