Movements respond to constraints from different sources (Bernstein, 1967; Higgins, 1977; Newell, 1986). Physical laws impose biomechanical constraints. For example, greater ground forces, and not the rapid movements of the legs, are responsible for running fast (Weyand et al., 2000). The physical structure and physiological makeup of the body impose morphological or anatomical constraints. For example, because of several derived anatomical features that enable elastic energy storage and release at the shoulder humans can throw projectiles; other species cannot throw projectiles because they lack these features (Roach et al., 2013). The extraneous factors that may affect task performance impose environmental constraints. For example, people
