Like the squat, the deadlift involves the largest muscle groups in the body: the gluteus maximus, hamstrings, quadriceps and erector spinea. And like the squat, it is a very hard, taxing exercise to perform. Consequently, for this reason alone many people don’t use the deadlift in their routines.
The gluteus maximus is utilized most in the beginning of the movement when there is a large degree of hip flexion. The glutes work in unison with the hamstring to extend the hips. The hamstrings, located on the back of the upper thigh, become more involved as you begin to decrease the degree of hip flexion as you raise the weight. The erector spinea, which run the length of your spine on both sides, are statically contracted throughout most of the movement keeping the normal curvature of the spine. A static contraction of the rhomboids and the trapezius muscles help maintain the shoulders. The quadriceps muscles are involved with knee extension.
Extension of the body occurs when the upper body, torso and pelvis rotate up and back. In a properly performed deadlift, this will happen simultaneously with the hips moving forward and the knees extending. Two of the biggest mistakes I see when this movement is performed are locking the knees out before the upper body is extended or allowing the back to “round” and magnifying the kyphotic (upper back) curvature while de-emphasizing the lordotic (lower back) curvature. I need to add that a slight curve of the upper back will present no danger and will happen to most while using heavy weight, but if you look like the hunch back of Notre Dame while performing the exercise that’s a different story.
The main reason your lower back would round, which could cause devastating trauma to the lumbar area, is weak erector muscles. There are various exercises you can use to strengthen your lower back like good mornings, arched back good mornings, arched back stiff legged deadlifts, and reverse hyperextensions, but good mornings and its variation in my opinion are probably the best exercise for this purpose.??????
