i have excellent explosive power and pound for pound strength, but my muscular endurance is horrendous. this is never more obvious than when rolling or hitting the mitts/heavy bag at full force. i rarely endure the entire round of striking as either my shoulders or chest will give out, and my hams and back/biceps give out when rolling much faster than my cardiovascular. how can i increase muscular endurance without sacrificng power? is it possible? if i can't win early i have a very difficult time winning at all.