HOW PAIN AFFECTS MOVEMENT
Repeated pain stimuli may in turn lead to hyperalgesia, central sensitization, and expansion of the pain receptive field. These changes in peripheral and central mechanisms are not without implications on the motor system, as they can in turn lead to changes in motor behavior.
The Effects of Fatigue on Motor Behavior
Fatigue is a general state of fatigue for long periods of time. However, in this section, fatigue will be defined as the reduction in functional capacity (force and power) of a muscle produced by sustained or repetitive use of that muscle (ie, muscle fatigue).
Fatigue has been shown to elicit declines in position sense.
Increasing coactivation of agonist-antagonist muscle pairs.
Alterations in inter- muscle relationships between groups of synergistic muscles.
Changes in whole-body movement patterns.
The Effects of Pain on Motor Behavior
Decreased activity of the painful muscles combined with increased involvement of nonpainful ones (in the acute stage of pain, the central nervous system is presumably in an experimenting state, searching for a motor solution to immediately reduce nociceptive influx).
Protection (bracing), generalized lower movement speed with pain.
Decreased motor variability (Movement to movement change) in chronic pain.
There is a possible link between perceptual, evaluative, and emotional processes with pain-affected movement patterns.
HOW EXERCISE AFFECTS PAIN
Exercise-induced hypoalgesia (EIH) is the decrease in pain in response to exercise.
Exercise Prescription in Healthy Individuals
Several research studies have reported that EIH occurs with static (ie, isometric) contractions of various intensities including brief maximal and sustained submaximal contractions. Duration, however, is an important component in regard to submaximal contractions.
Fatigue is not required to produce EIH because of the occurrence after the brief maximal contractions in which there was no exercise induced decrease in force.
The greatest decrease in pain occurred after the low-intensity (25% MVC) contraction held to exhaustion.
EIH is not restricted to the exercising body part. This indicates that an individual with localized pain may exercise a nonpainful body part to experience relief.
Exercise Prescription in Patients with Musculoskeletal Pain
Exercise is beneficial and is effective for several types of pain conditions, including fibromyalgia, osteoarthritis, low back pain, pelvic pain, neck pain, rheumatoid arthritis, and patellofemoral pain.
Exercise has the potential to influence all aspects of the biopsychosocial model of pain mechanism.
Specific to chronic pain, exercise fear-avoidance beliefs, decreases pain catastrophizing and depression, which was similar to the decreases that occurred with cognitive-behavioral treatment.
Initial pain response of an exercise program do not predict the long-term response.
Researches compared different types of exercises and their effects on the MSK pain. In conclusion, increasing general activity seems to be beneficial, with the optimal type and dosage to eb individually tailored.
Update on the Relation Between Pain and Movement: Consequences for Clinical Practice
Julie N. Cote, PhD* and Marie K. Hoeger Bement, PT, PhDw