Muscle pain is caused by triggering specialized nerve endings, also known as nociceptors. Exercise gives rise to muscle tissue damage and lowered tissue pH. Muscle pain is produced by the activation of these specialized nerve receptors, which detect stimuli that are capable of damaging tissue and these stimuli are perceived as painful. The nociceptors can be sensitized and activated by mechanical stimuli, such as trauma, exercise or mechanical overloading.
Two activating chemical substances are crucial for the generation of muscle pain: adenosine triphosphate (ATP) and protons (H+ ions). These chemical compounds activate nerve endings by binding to receptor molecules located in the membranes of the nerve endings.
Chronic muscle pain prevents the body from relaxing, which interrupts restful (delta wave) sleep. The lack of restful sleep significantly amplifies a pain patient’s perception of pain. Muscle pain resulting from exercise will also affect subsequent muscle movement, as further movement and contraction of the muscles will generate a greater degree of tissue trauma and increase the release of ATP and H+ ions around the tissue, further triggering nociceptors.
