Mechanical Misconceptions: Have we lost the “mechanics” in “biomechanics”?

In theory, everything in biomechanics stems from two disciplines, physics and biology. While a number of papers, editorials, letters to the editor, and even a review have addressed the misapplication of mechanical principles, the misapplication of the basic principles of physics in the field of biomechanics continues. There are three principles, specifically, that have been misapplied that we address: 1) reaction forces as they pertain to joint reaction forces; 2) the treatment of scalar quantities with direction; and 3) the terms weightlessness, microgravity, hypergravity, and unweighted.