The alternating dumbbell hammer preacher curl is a good exercise for isolating the biceps, working the forearms, and making the muscles work independently.
- Adjust the height of the seat on the preacher bench so that when you sit on it the back of your upper arms sit comfortably flat on the padding.
- Grab a set of dumbbells and sit on the preacher bench. Your arms should be resting on the padding and be around shoulder width apart.
- You will be using a neutral grip (palms facing each other). Allow the weight to drop and the arms to fully extend. This is the starting position for the exercise.
- Starting with your weakest arm (usually the left), slowly curl the dumbbell up as far as possible, squeezing the bicep at the top of the movement.
- Lower the weight back until your arm is fully extended, and repeat for the other arm.