Is implicit motor imagery altered in people with shoulder pain? The shoulder left/right judgement task.

BACKGROUND

Implicit motor imagery performance is altered in a variety of chronic pain conditions, but it is not known whether this is the case in shoulder pain.

OBJECTIVES

The aim of this study was to assess implicit motor imagery performance, using a valid and reliable shoulder left/right judgement task in people with shoulder pain.

DESIGN

Cross-sectional observational study.

METHODS

Participants with (n = 369) and without (n = 747) shoulder pain completed the shoulder left/right judgement task (LRJT). Response times (RT), accuracy were determined. Age, gender, hand dominance, current pain intensity, Shoulder Pain and Disability Index (SPADI) and pain duration recorded. Planned analysis included ANOVAs for current pain, RT and accuracy.

RESULTS

Gender and hand dominance distribution were similar between groups (p > 0.5). The shoulder pain participants were older, mean age (SD); 47(14)years, than the control group; 41(14)years, p < 0.01. Participants with shoulder pain were slower, mean RT(SD); 1809(746)ms than the controls; 1701(749)ms; p = 0.02, but no different in accuracy, mean % (SD); 93.2(8.5)% to controls; 94.1(9.4)%; p = 0.13. The differences in RT were resolved when age was entered as a covariate (p = 0.83). Regression of the data from the shoulder pain group only found that current pain was positively related to RT (B = 43.97) and negatively to accuracy (B = -0.70).

CONCLUSIONS

Participants with shoulder pain do not demonstrate poorer implicit motor imagery performance than people who are pain-free. However, more intense shoulder pain is associated with poorer implicit motor imagery performance. We recommend further research utilising the LRJT in well-defined clinically homogenous groups, with verified pain severity, functional disability, and chronicity.