Symptom fluctuations and daily physical activity in patients with
chronic fatigue syndrome: a case-control study.
Meeus M, van Eupen I, van Baarle E, De Boeck V, Luyckx A, Kos D, Nijs J.
Archives of Physical Medicine and Rehabilitation Volume 92, Issue 11 ,
Pages 1820-1826, November 2011
To compare the activity pattern of patients with chronic fatigue
syndrome (CFS) with healthy sedentary subjects and examine the
relationship between the different parameters of performed activity
(registered by an accelerometer device) and symptom severity and
fluctuation (registered by questionnaires) in patients with CFS.
Case-control study. Participants were asked to wear an accelerometer
device on the nondominant hand for 6 consecutive days. Every morning,
afternoon, and evening patients scored the intensity of their pain,
fatigue, and concentration difficulties on a visual analog scale.
Patients were recruited from a specialized chronic fatigue clinic in
the university hospital, where all subjects were invited for 2
appointments (for questionnaire and accelerometer adjustments). In
between, activity data were collected in the subject's normal home
Female patients (n=67) with CFS and female age-matched healthy
Main Outcome Measures
Accelerometry (average activity counts, peak activity counts, ratio
peak/average, minutes spent per activity category) and symptom
severity (intensity of pain, fatigue, and concentration difficulties).
Patients with CFS were less active, spent more time sedentary, and
less time lightly active (P<.05). The course of the activity level
during the registration period (P interaction>.05), peak activity, and
the staggering of activities (ratio peak/average) on 1 day were not
different between groups (P>.05). Negative correlations (–.242 varying
to –.307) were observed for sedentary activity and the ratio with
symptom severity and variation on the same and the next day. Light,
moderate, and vigorous, as well as the average activity and the peak
activity, were positively correlated (.242 varying to .421) with
symptom severity and variation.
The more patients with CFS are sedentary and the better activity is dispersed, the fewer symptoms and variations they experience on the same and next day. Inversely, more symptoms and variability is experienced when patients were more active that day or the previous day. The direction of these relations cannot be determined in a
cross-sectional study and requires further study.