Association between task performance and tender point pain threshold to pressure in normal subjects

Objective: Work action patterns associated with increase in pain sensitivity in healthy people may be valuable predictors of patterns which will cause pain in those with pre-existing low pain threshold. This study aimed to establish whether pain threshold to pressure [PPT], a measure of pain sensitivity, varies in association with task performance, particularly with tasks containing the ergonomic pain risk characteristics of frequent repetition and static muscle work. Method: Designated unilateral manual activity, bilateral manual activity and non-manual activity were examined sequentially. Pain threshold to pressure at two tender points [TeP] was measured bilaterally before and after two hours performance of three unilateral tasks varying in continuous light control and grasp-release; two bilateral tasks, varying in continuous holding, grasp-release and force exertion and one non-manual quiz game. Results: After the unilateral tasks, reduction in PPT at the TeP 2cm distal to the lateral epicondyle was shown on both the active and inactive side without difference in amount of change between tasks or sides. Probability of reduction was greater after grasp-pull-release than light continuous control and was lessened by alternation between these two. After each bilateral task, reduction was shown bilaterally at both TePs, probability at the site 2cm distal to the lateral epicondyle being higher after prolonged holding with repeated force than force following unresisted grasp and release. There was no PPT change after the non-manual task. Conclusion: In normal subjects repetition frequency, static muscle work and force can influence probability of reduced PPT on both the side used and contralateral side, and in fewer cases influence the size of that change.