Sarcomere length of free and restrained bovine muscles at low temperature as related to tenderness

Tenderness of semitendinosus and psoas major bovine muscles was markedly affected by: (1) allowing the muscle to undergo rigor mortis and the associated contraction, following pre‐rigor excision, or by (2) pre‐rigor excision followed by restraint in a stretched state while the muscle undergoes rigor mortis. The extent of stretch or contraction induced by pre‐rigor treatment was reflected by the sarcomere length. The average sarcomere length of the semitendinosus and psoas major muscles differed widely when samples were removed post‐rigor from the carcass. The data indicate that the state of contraction (measured by sarcomere length), when altered in different portions of the same muscle by treatment, or when varying naturally in different muscles, was associated with tenderness.