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Introduction: When performing an exercise or a functional test, pain that is evoked by movement or muscle contraction could be a stronger stimulus for changing how individuals move compared to tonic pain. We investigated whether the decrease in muscle force production is larger when experimentally‐induced knee pain is directly associated to the torque produced (movement‐evoked) compared to a constant painful stimulation (tonic). Methods: Twenty‐one participants performed three isometric knee extension maximal voluntary contractions without pain (baseline), during pain, and after pain. Knee pain was induced using sinusoidal electrical stimuli at 10 Hz over the infrapatellar fat pad, applied continuously or modulated proportionally to the knee extension torque. Peak torque and contraction duration were averaged across repetitions and normalized to baseline. Results: During tonic pain, participants reported lower pain intensity during the contraction than at rest (p < 0.001), whereas pain intensity increased with contraction during movement‐evoked pain (p < 0.001). Knee extension torque decreased during both pain conditions (p < 0.001), but a larger reduction was observed during movement‐evoked compared to tonic pain (p < 0.001). Participants produced torque for longer during tonic compared to movement‐evoked pain (p = 0.005). Conclusion: Our results indicate that movement‐evoked pain was a more potent stimulus to reduce knee extension torque than tonic pain. The longer contraction time observed during tonic pain may be a result of a lower perceived pain intensity during muscle contraction. Overall, our results suggest different motor adaptation to tonic and movement‐evoked pain and support the notion that motor adaptation to pain is a purposeful strategy to limit pain. This mechanistic evidence suggests that individuals experiencing prevalently tonic or movement‐evoked pain may exhibit different motor adaptations, which may be important for exercise prescription. [ABSTRACT FROM AUTHOR]

Objective: This explorative study investigates the moderating effect of sex and baseline pain characteristics on the effectiveness of preoperative pain neuroscience education (PNE) plus knee joint mobilization versus biomedical education plus knee joint mobilization in patients who have knee osteoarthritis and are scheduled to undergo total knee arthroplasty (TKA). Methods: After baseline assessment of self-reported questionnaires (pain intensity, disability, symptoms of central sensitization and pain cognitions) and quantitative sensory testing, 44 participants with knee osteoarthritis were randomized into the PNE plus knee joint mobilization or biomedical education plus knee joint mobilization group. The questionnaires were retaken directly after and 1 month after 4 sessions of treatment and at 3 months after surgery. Based on baseline quantitative sensory testing results, the sample was subdivided into a high (showing high experimental pain levels and low pressure pain thresholds) and low pain cluster using principal components analysis and cluster analysis. Therapy effects over time were evaluated using 3-way analysis of variance, with time as the within factor and treatment, sex, and baseline pain cluster as between factors. Results: Women benefited significantly more from the PNE intervention compared with the control intervention in terms of self-reported symptoms of central sensitization. For both pain clusters, differences in therapeutic effects concerning pain intensity and pain cognitions were found, with higher superiority of the PNE intervention in the high-pain cluster subgroup compared with the low-pain cluster. Conclusion: Based on these explorative analyses, it can be concluded that sex and preoperative pain measures may influence the effectiveness of preoperative PNE for some specific outcome measures in people scheduled to undergo TKA. Impact: Although further research on this topic is needed, the potential influence of sex and preoperative pain measures on the effectiveness of preoperative PNE should be considered when implementing this intervention in people undergoing TKA. [ABSTRACT FROM AUTHOR]

Background. Expanded distribution of pain is considered a sign of central sensitization (CS). The relationship between recording of symptoms and CS in people with knee osteoarthritis (OA) has been poorly investigated. Objective. The aim of this study was to examine whether the area of pain assessed using pain drawings relates to CS and clinical symptoms in people with knee OA. Design. This was a cross-sectional study. Methods. Fifty-three people with knee OA scheduled to undergo primary total knee arthroplasty were studied. All participants completed pain drawings using a novel digital device, completed self-administration questionnaires, and were assessed by quantitative sensory testing. Pain frequency maps were generated separately for women and men. Spearman correlation coefficients were computed to reveal possible correlations between the area of pain and quantitative sensory testing and clinical symptoms. Results. Pain frequency maps revealed enlarged areas of pain, especially in women. Enlarged areas of pain were associated with higher knee pain severity (rs=.325, P<.05) and stiffness (rs=.341, P<.05), lower pressure pain thresholds at the knee (rs= -.306, P<.05) and epicondyle (rs=-.308, P<05), and higher scores with the Central Sensitization Inventory (rs=.456, P<.01). No significant associations were observed between the area of pain and the remaining clinical symptoms and measures of CS. Limitations. Firm conclusions about the predictive role of pain drawings cannot be drawn. Further evaluation of the reliability and validity of pain area extracted from pain drawings in people with knee OA is needed. Conclusion. Expanded distribution of pain was correlated with some measures of CS in individuals with knee OA. Pain drawings may constitute an easy way for the early identification of CS in people with knee OA, but further research is needed. [ABSTRACT FROM AUTHOR]