The single leg deadlift is used to build the hamstrings while also helping with balance and thoroughly working the stabilizer muscles in the core and lower body.
Begin with a dumbbell in one hand, and stand on one leg. You should stand on the leg which is on the side of your body that is holding the dumbbell. For example, if the dumbbell is in your right hand, then you should stand on your right leg. Keep your knee slightly bent and begin to bend forward at the waist. Continue to bend over until your torso is parallel with the floor. Your opposite leg should be extended behind you, and you should feel a good stretch in your hamstring. Next, return to the upright position, by pulling your torso back and standing up. Repeat this movement for a set number of repetitions, and then repeat with the other leg.
This movement can also be done with kettle bells.