During doing biceps curls my biceps is exhausted and I cant do another repetition after 13 reps. But if I lay down the Barbel for 10 seconds, I can do 12/13 reps again. And that for like 4 to 5 sets. The next day and after the workout I don't feel my biceps at all. So what can I do to stop that from happening? Thank you for your help!