“The deadlift places significant stress on your back. If you perform the exercise wrong or use a weight that is too heavy and compromises your technique, you increase the risk of hurting your lower back. Don't shrug your shoulders at the top of the movement when you perform deadlifts. According to physical therapist and strength coach Gray Cook, this inhibits the ability of your rotator cuffs to stabilize your shoulders and may cause injury.”
http://www.livestrong.com/article/530260-what-happens-if-i-do-a-deadlift-wrong/
