New research shows that the pain signal may be simply an "electrical leak" from an ion channel. As previously written there is a connection between the opening and closing of ion channels and electrical polarity charges. The new finding by a team of scientists at KU Leuven indicates the actual pain message is electrical and is short circuited due to chemical changes in the ion channels. The ongoing research is showing the chemical and physical relationship of pain and electrical polarities.
Applied kinesiology is a "balancing" or homeostatic equaling used to maintain and restore function. Often the term is used that one must "lengthen muscles" which apparently is meant to indicate the ability to make the muscle more elastic is necessary. Often if there is warmth applied to muscle tissues, occurs with increased blood flow due to the higher heat of blood moving away from the heart, then the thermal effect allows extension or more elasticity to the muscles.
Always, with increased blood flow, there are extended benefits of more oxygen, greater nutrient matter, and enhanced ability to move waste products away from the muscle tissues. The waste products can be the result of increased exercising and the quicker the waste is removed then the longer the patient can exert. This is known as "conditioning" or increasing endurance while extending range of motion.
The Infrex Plus unit is capable of increasing muscle length and is used for eccentric contractions. This well made video is illustrative of the concept of muscle lengthening using electro stimulation for functional restoration.