Biomechanical Analysis of the Deadlift: The three directions in which forces are applied to human tissues are compression, tension, and shear. Shear is defined as a force that acts parallel to a surface; in the spine, it can create sliding of one vertebra with respect to another. Bending creates compression on one side of the object and shear on the other side. While deadlifting, if you maintain the natural curvature of your lumbar spine, the spinal erector musculature will create the opposing t