Abstract
Movement adapts during acute pain. This is assumed to reduce nociceptive input, but the interpretation may not be straightforward. We investigated whether movement adaptation during pain reflects a purposeful search for a less painful solution. Three groups of participants performed two blocks (Baseline, Experimental) of wrist movements in the radial-ulnar direction. For the Control group (n = 10) both blocks were painfree. In two groups, painful electrical stimulation was applied at the elbow in Experimental conditions when the wrist crossed radial-ulnar neutral. Different stimulus intensities were given for specific wrist angles in a secondary direction (flexion-extension) as the wrist passed radial-ulnar neutral (Pain 5–1 group:painful stimulation at ~5 or ~1/10—n = 21; Pain 5–0 group:~5 or 0(no stimulation)/10—n = 6)). Participants were not informed about the less painful alternative and could use any strategy. We recorded the percentage of movements using the wrist flexion/extension alignment that evoked the lower intensity noxious stimulus, movement variability, and change in wrist/forearm alignment during pain. Participants adapted their strategy of wrist movement during pain provocation and reported less pain over time. Three adaptations of wrist movement were observed; (i) greater use of the wrist alignment with no/less noxious input (Pain 5–1, n = 8/21; Pain 5–0, n = 2/6); (ii) small (n = 9/21; n = 3/6) or (iii) large (n = 4/21; n = 1/6) change of wrist/forearm alignment to a region that was not allocated to provide an actual reduction in noxious stimulus. Pain reduction was achieved with “taking action” to relieve pain and did not depend on reduced noxious stimulus.
Highlights
Theories of the motor adaptation to pain [1,2,3,4] posit that movement is altered by the nervous system as a purposeful attempt to reduce nociceptive input and pain, and to protect structures from further injury
The purpose of the adaptation appears straightforward–to reduce pain by reducing nociceptive input–it has not been tested: whether nociceptive input is reduced in the adapted movement solution; why a particular movement strategy is selected from the many options that are available; and how the search is conducted
The results of this study provide novel observations and new understanding of the movement adaptation to pain
Summary
Theories of the motor adaptation to pain [1,2,3,4] posit that movement is altered by the nervous system as a purposeful attempt to reduce nociceptive input and pain, and to protect structures (e.g. muscle, ligament) from further injury. Modified movement can reduce the subjective report of pain [15], this does not confirm reduced nociception This is because pain and nociception are not linearly related. It has been argued that “taking action” (i.e. choosing a new movement strategy with the intention to reduce pain/threat) is sufficient to reduce the experience of pain, despite no change in nociceptive input [17]. It is not yet clear whether reduced excitation of peripheral nociceptors is necessary to achieve pain relief from an adapted movement strategy during a painful movement
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
