Telling a gym rat he can't do curls is like asking a porn star to abstain from sex-it defeats the purpose. And while we won't stop you from sliding more weight onto the bar, your body may. Sooner or later, you're going to hit a plateau, and you simply won't be able to lift any more weight. Unless, that is, you try a move like this biceps shocker (think of it as a negative curl), courtesy of Mike Mahler, a strength coach in Los Angeles (for more on his program, check out mikemahler.com).
HERE'S WHAT YOU DO
Load the bar with 20% more weight than you can lift for five reps. (For instance, if you can curl 100 pounds for five reps, load the bar with 120.) Now have a partner help you lift the bar up to the fully contracted position (the top of a curl, when your elbows are fully bent). If you don't have a partner handy, explosively "cheat curl" the weight into position . Hold the position for two seconds, tensing every muscle in your body and squeezing the bar as tightly as you can. Now take four seconds to lower the weight  until your arms are fully extended. Rest one minute, and then begin your regular sets. You should be able to use a slightly heavier weight than you're used to.
"Using your whole body to support the weight on the negative turns on more muscle fibers than usual-and not just in your arms," says Mahler. By using more muscle, you'll be able to lift heavier. "The weight you're now working with-although it's heavier than what you've ever used before-feels lighter in comparison to the negative curl, so you'll lift with more confidence." And isn't that the real reason you train, anyway?