Motor Control Changes and Pain

Original Editor - Tarina van der Stockt

Top Contributors - Tarina van der Stockt, Kim Jackson, Lucinda hampton and Rachael Lowe  

Introduction

Motor control is the "ability to regulate or direct the mechanisms essential for movement". Previous motor control theories explained that pain leads either to muscle inhibition or muscle spasm. Older theories postulated a vicious cycle of pain where muscles become hyperactive Movement is played out in an interaction between the person, environment and the task. Newer theories describe pain as more individualised and that it will depend on the person, the task, and the environment. Movement in itself is an interaction of different body systems like "sensory/perceptual, cognitive, and motor/action"

A person's functional capacity is determined by the individual's capacity to meet the demands of the environment and the task.

In the rehabilitation of movement disorders, the individual will practice different tasks, but it is not always clear which tasks, in what order and when it should be practised.

People move differently due to the influence of pain, either the threat, the presence, resolution, or precursor of pain. Changes could be beneficial or problematic:

• Beneficial: after an acute ankle sprain, a person will be partial or non-weight bearing and avoid dorsiflexion
• Beneficial: during back pain the trunk muscles co-contract to limit movement and pain
• Problematic: an increase in muscle activation is also a predictor of recurrent low back pain
• Beneficial and problematic: in the acute phase after an ankle sprain a person might avoid load on the injured ligament, and might walk with the leg externally rotated, but this increases the demand on the proximal joints and can lead to persistent ankle stiffness.

There are 4 main ways motor control changes happen with regards to pain, nociception, injury or even the anticipation of them. Hodges (2016) summarised the finding of different authors as follows:

1. Suboptimal movement/motor control as a precursor to injury and pain

2. Impaired movement/motor control as a consequence of interference by actual or threatened injury and/or pain

3. Modification of movement/motor control for the protection of the painful/injured/threatened region

4. Modified movement/motor control explained by a conditioned association with pain

Each one of these ways will look different in every individual and will influence them in different ways. They may also overlap and the order might be different. These differences in individuals need to be considered when doing an assessment and planning rehabilitation.

Suboptimal movement

This is where alignment or movement loads tissues suboptimally.

• Repetition -
  • examples: poor posture, poor joint alignment during movement, poor coordination or control between different segments of the body
  • empirical evidence is limited
  • different schools of thought
    1. continued repetition of suboptimal movement could be a precursor to pain or injury or be a risk factor for recurrence
    2. Many people
• Single loading events that lead to nociception, tissue injury, or pain
  • this is like a slip or a fall
  • unexpected force or high load in a suboptimal position
  • the person may have optimal movement or motor control but load exceeded the tissue capacity

The primary argument against this proposal is that there

are many people who use strategies that are deemed “negative,” but are pain/injury free, and

therefore questioning the relationship to nociceptive input/pain/injury. The counterargument is

that for a specific movement/loading strategy to cross the “threshold” and induce nociceptive

input/pain/injury there must be sufficient “exposure” [13]; whereas high forces can exceed

tissue tolerance with as few repetitions as one, low forces may require repeated exposure over

an extended period to exceed the threshold. Add to this potential individual variation in the

resilience of tissues and psychosocial context, and the equation between loading strategy and

pain/injury becomes complex. Furthermore, there will not

Motor control refers to all of the motor, sensory, and information-processing elements associated with generation of motor functions [61]. Differences in any (or all) of these elements may be present in an individual with present, previous, or threatened pain. For the patient in pain, consideration of motor control may be critical for recovery, and to address these issues may be a major element of intervention. This chapter provides an overview of the contemporary view of motor control changes in pain, possible mechanisms, and potential benefits of treatments that aim to change the way a patient moves.