Youre a facking idiot, it means youre f-ing doing it wrong. When i do my sets to failure, my body is trying to talk me out of doing the next set cause its so bloody exhausting. It means you are doing high reps but not loading enough weight. Oh and yea, youre a idiot. TDS, burns out the muscles completely unless you are doing it like an idiot. You are supposed to do a weight at which you reach failure at 15 reps, then immediately you drop the weight, say maybe from 10 plates you drop to 7 plates and you do till failure, then you repeat this 2 times more. So in total you drop your weight 3 times, if you do it correctly you shouldn't be not aching. Get your ideas right bro.