The bicep curl is dead. After a long life of being the must-do movement for guys with gym cred, the curl is no longer cool, as even some gym rats have embraced more functional exercise. "It looks way too narcissistic to blast only your biceps by curling like an extra in some seventies prison-yard film," says celebrity trainer Gunnar Peterson. Curls primarily train the small (but mostly useless) biceps muscle, and doing too many too often can lead to bad posture and shoulder or elbow injury. "Curls pull your shoulders forward and bend your elbow out," says celebrity trainer Harley Pasternak, whose clients include Robert Downey Jr. and LL Cool J. "If your biceps are stronger than your triceps – which is the larger, stronger, and more important muscle – it will make your arms look shorter and your pecs droopy, and give you gorilla posture." So skip the arm pumps in the mirror and pay more attention to your tris. If you train your lats or rhomboids, you'll work your biceps plenty.