Humane methods differ by country, with the most appropriate based on ethical approval and researcher skill level.
A number of further criteria should be followed to ensure the animal is completely dead without the possibility of recovery, which includes cessation of blood flow via the removal of the heart from the circulatory system and/or complete destruction of the brain and spinal column.
Pieces of bone can be left at the proximal and/or distal end of skeletal muscles to allow for anchoring.
In vitro muscle testing typically requires a dual-mode servomotor, which can both control and detect changes in force and length.
Muscle fibers may be intact, or may be "skinned", a process which removes the cell membrane, sarcoplasmic reticulum, and cytoplasm, allowing greater access to the contractile components of the sarcomere.
Several properties are commonly tested, and a given experiment will often use a subset of these properties, including twitch times, tetanic force, force-length relationship, force velocity relationship, work loops, fatigue trials, fusion frequency, and energetic cost.
This ensures the muscle is kept at the right temperature and amply supplied with nutrients and oxygen by the blood, but the procedure is more difficult and some tests may not be possible.
[1] In vitro testing allows for exact stimulation of the muscle, providing precise data on innate tissue behavior.
In vitro isolated muscle testing is a beneficial procedure based on its ideal accuracy, precision, and reproducibly.