This exercise emphasizes your biceps' effort during the eccentric (lowering) phase while also targeting your legs, core, and shoulders all at the same time.
To do it: Stand in a split stance with your left foot in front of your right, holding a heavy dumbbell with your right hand.
Keeping your weight forward and into your left foot, allowing your right heel to come off the floor, press the dumbbell up and slightly in front of you with your right arm.
Slowly and with control, bend both knees and start to lower your body to the floor as you bend your right elbow, resisting gravity as you slowly start to draw the dumbbell down to the front of your shoulder. Lower as deeply as you can, keeping your back straight and your abs drawn in tight.
Stand up out of the squat and quickly press the dumbbell back up and out (take four counts to lower, one count to press up). That's one rep. Try to do up to 15 reps on one side, and then try 15 on the other.
Options: You can also do this move with a barbell or a body bar by placing one end on the floor in front of you and holding the other end in your hand. Be sure to choose a weight that is heavy enough to be challenging but not so heavy that you lose control at any point.