Even after a good warm-up, your muscles may still be asleep-and we're not talking about that pins-and-needles feeling. Rather, the muscles you're training may not have been adequately primed to lift a big load. In order to wake them up without wearing them out, try this trick from Todd Scott, a trainer in Baton Rouge, La., that will have your biceps and shoulder stabilizers buzzing before curls.

Perform a neutral-grip front raise: Stand holding a dumbbell in each hand, your palms facing each other [1]. Raise your left arm in front of you until the weight is eye-level [2], then slowly lower it to the starting position. Repeat the move with your right arm - that's one rep. Do three sets of four reps, resting 90 seconds between sets, and then go on to hammer curls.

While most front raises just work the delts, this neutral-grip variation forces your biceps (and other curling muscles) to contract isometrically, which keeps your elbow from being overextended by the heavy weight. By overloading those muscles briefly, you spur a significant increase in strength for the hammer curls that follow. At the same time, the raise causes your central nervous system (the coordinator of all muscle actions) to fire up the muscles in your shoulders that help stabilize a curl, helping you better control that heavier weight. When you follow your front raises with a hammer curl (which uses the same grip), you'll target the arm differently than the conventional, palms-up version, and that will awaken a new realm of muscle growth.