Background: In patients with chronic fatigue syndrome (CFS), performance of physical activities may be affected by an anticipated increase in symptoms after these activities. Nijs et al. previously studied the influence of symptom expectancies and related psychological processes on the performance of an isolated physical activity [Nijs J, Meeus M, Heins M, Knoop H, Moorkens G, Bleijenberg G. Kinesiophobia, catastrophizing and anticipated symptoms before stair climbing in chronic fatigue syndrome: an experimental study. Disabil Rehabil 2012. doi: 10.3109/09638288.2011.641661 .].
Purpose: We aimed to validate the previous findings in a larger group of patients in a different setting. We also extended the possible underlying psychological processes studied.
Method: In 49 CFS patients, we measured performance (duration and increase in heart rate) during self-paced climbing and descending of two floors of stairs. Before this task, patients rated experienced fatigue and anticipated fatigue after stair climbing. In addition, kinesiophobia, catastrophising and focusing on bodily symptoms were measured. Using correlational and regression analyses, we tested whether performance during stair climbing could be explained by experienced and anticipated fatigue and psychological factors.
Results: Longer duration of stair climbing correlated with higher anticipated fatigue, independently of sex, age, body mass index and fatigue before stair climbing. Focusing on bodily symptoms and fatigue-related catastrophising were related to anticipated fatigue.
Conclusion: Symptom expectations affect the performance of physical activity in CFS patients, possibly through focusing on bodily symptoms and catastrophising. These findings partially contradict the findings of the previous study, which stresses the importance of study context in conducting this type of experiments (i.e., patient characteristics, instructions).