I guess weighing in somewhere between 210-200 for a woman would put me in the heavy category and yes I do run sprints. I also run them barefoot and love them. I pretty much go full bore on them and I go to a local bike/walk path that has differing levels of grades for mine. I try to do 10-20 min of sprints once to twice a week. The very first sprint run, I ended up having charlie horses in my calves the following morning and I supp with potassium and magnesium daily. The second time, no pains/cramps whatsoever. Sprints definitely help to change body comp and its awesome to see and feel that.