Simply put, when i am running/skipping rope, my legs get sore and burn up LONG before my lungs do, so i never get some good cardio going while doing LSD, or at least i am never able to get to that point cause the muscle soreness causes me to stop before i can "get going" so to speak. I have pretty large powerful calfs, and i go hard in powerlifting 3x week. so i don't know what the problem is here. Could this be a muscle endurance issue? How would i remedy this issue? Should i just keep working at doing LSD until my muscles aren't sore anymore? I'm really confused here because doing sprints works my lungs/cardio real well, and i don't get sore that fast doing them. I have even come a long way in powerlifting, but slow/moderate steady running/skipping is really challenging me. input?