The right way to curl: Let the dumbbells hang at arm's length straight down from your shoulders. Then, without moving your upper arms, bend your elbows and curl the dumbbells as close to your shoulders as you can. Pause, and slowly lower the weights back to the starting position. Each time you return to the start, straighten your arms completely
Choose your hand position
STANDARDWith your palms facing forward, grip the handles in the middle
The benefit: This is the hand position for the classic dumbbell curl, which targets your biceps brachii, the largest muscle on the front of your upper arm. (Try these eight exercise upgrades for more muscle.)
THUMB OFFSETWith your palms facing forward, touch the outside heads of the dumbbells with your thumbs.
The benefit: As you curl the weight, you're forcing your biceps brachii to work harder to keep your forearm rotated outward (so your palms are up).