I was in the gym the other day doing the calf raise on the leg press machine. After 20 reps or so, on the top of the movement, where my feet were extended, I felt this incredible pain in my right calf. As I took the weight down, my calf muscle was bulged out. I never experienced this before. It was in great pain! As I got up, it was hard to walk and one of the personal trainers saw my calf sticking out and was alarmed at the sight of it. I stretch before and after always, drink plenty of water, so I do not know why this happened. Anyway, it is still sore. I was using 180# on the leg press machine, and I can usually do 2-3 sets of 25 reps, so the weight does not feel that heavy. Anyone experience this and knows what causes muscles to do this?