Deadlift refers to the lifting of dead weight (weight without momentum), such as weights lying on the ground. It is one of the few standard weight training exercises in which all repetitions begin with dead weight. There are several positions one can approach when performing the deadlift, which include the conventional deadlift, squat, and sumo-deadlift. In most other lifts there is an eccentric (lowering of the weight) phase followed by the concentric (lifting of the weight) phase. During these exercises, a small amount of energy is stored in the stretched muscles and tendons in the eccentric phase if the lifter is not flexible beyond the range of motion. Although this exercise uses the hips and legs as the primary movers, it can just as easily be considered a back exercise.