Lack of gender and age differences in pain measurements following exercise in people with chronic whiplash-associated disorders

Abstract

Background: Individuals with chronic whiplash associated disorders (WAD) present persistent pain in the absence of structural pathology. In these people, altered central pain processing and central sensitization are observed. The role of personal factors, such as gender and age, on pain processing mechanisms in chronic WAD, however, is still unclear. Objectives: This study investigated possible gender- and age-related differences in self-reported and experimental pain measurements in people with chronic WAD. Besides the exercise-induced response on pain measurements between gender and age subgroups was recorded. Study Design: Case-control study. Setting: University Hospital, Brussels. Methods: Self-reported pain and experimental pain measurements (pressure pain thresholds [PPT], occlusion cuff pressure, temporal summation, and conditioned pain modulation) were performed in 52 individuals (26 chronic WAD patients and 26 healthy controls), before and after a submaximal cycle exercise. Results: Lower PPTs and occlusion cuff pressures were shown in chronic WAD in comparison with healthy controls. No gender and age differences regarding PPTs, occlusion cuff pressures and conditioned pain modulation were found in chronic WAD. Within the chronic WAD group, men showed higher self-reported pain compared to women and younger adults showed enhanced generalized pain facilitation compared to older adults. In addition, chronic WAD patients are able to inhibit exercise-induced hyperalgesia, but no gender and age differences in pain response following exercise were found. Limitations: This study was sufficiently powered to detect differences between the chronic WAD and control group. However, a sufficient power was not reached when patients were divided in age and gender groups. Furthermore, only mechanical stimuli were included in the experimental pain measurements. Besides, psychosocial factors were not taken into account. Conclusion: Some alterations of altered pain processing are present in chronic WAD patients, however not in response to exercise. No gender and age differences in pain measurements were observed in people with chronic WAD.