Pick the dumbbells up off the ground using power from your legs (not your back). Space your feet slightly narrower than shoulder-width apart and hold the weights with your grip facing in, just outside of your legs. Keeping a slight bend in your knees, bend forward at the waist and lower the dumbbells toward the ground. As you lower the weights your lower back should remain arched as this will keep the tension on your hamstrings throughout the entire exercise. Lower the weights down until you feel a full stretch in your hamstrings. The distance that you are able to lower them will vary from person to person and will depend on body structure and flexibility. Once you feel a full stretch in your hamstrings, pull the dumbbells back up into the standing position but stop just short of being fully erect. By not allowing your body to stand up completely straight you will keep the stress on your hamstrings at all times. Continue the motion until you have reached muscular failure.
Tips:
To maximize the stimulation to your hamstrings, make sure that you use a full range of motion. This means curling the weight all the way up towards your body and getting a full stretch at the bottom. Do not rest the weights at any point during the exercise as this will take the stress off of your hamstrings.
