The removal of the muscle from the carcass during the pre-rigor phase allows the muscle to contract more than muscles that are conventionally chilled while attached to the skeleton, and the degree of contraction in which a muscle enters a state of rigor is highly variable among
different muscles of a carcass (Locker, 1960). Such contraction can arise from either a rigor contraction of muscle fibers entering rigor above the optimum temperature of 10–18 °C or from cold contracture occurring below this temperature (Hildrum, Nilsen, & Wahlgren, 2002).