Prediction of peak oxygen uptake in
patients fulfilling the 1994 CDC criteria for chronic fatigue syndrome.
Nijs J, De Meirleir K.
Department of Human Physiology, Faculty of Physical Education and Physical
Therapy and Chronic Fatigue Clinic, Vrije Universiteit Brussel, Belgium. Jo.Nijs@vub.ac.be
PURPOSE: To establish an inexpensive, simple method of predicting peak oxygen
uptake (VO2peak) in patients fulfilling the 1994 Centers for Disease Control
and Prevention (CDC) criteria for chronic fatigue syndrome (CFS). DESIGN: A
retrospective observational study. SETTING: An outpatient tertiary care chronic
fatigue clinic. SUBJECTS: Two hundred and forty consecutive patients fulfilling
the 1994 CDC criteria for CFS. INTERVENTIONS: Heart rate, metabolic and
ventilatory parameters were measured continuously during a maximal exercise
stress test on a bicycle ergometer. Using the equation peak oxygen uptake =
13.1 x peak workload +284 (used by Mullis et al., Br J Sports Med 1999; 33:
352-56), VO2peak was predicted from the peak workload of a maximal exercise
capacity test. Pearson correlation coefficient and linear regression analysis
were used to establish the most accurate way to predict VO2peak. RESULTS:
Percentage error encountered when comparing actual measured VO2peak with
predicted value was 17.3% (+/-10.0). A strong correlation between VO2peak and
peak workload was observed (r= 0.89, p < 0.001). A regression analysis
established the relation as VO2peak = 10.47 x peak workload +284.1, where
VO2peak is given in ml/min and peak workload in W (error in prediction =
11.0+/-9.5%). CONCLUSIONS: Monitoring of the peak workload during a maximal,
graded bicycle ergometric test suffices to predict the VO2peak. When predicting
VO2peak the used operational definition for the diagnosis of CFS could be taken
into account. Compared with the equation used by Mullis et al., peak workload
is multiplied by 10.47 in order to predict peak oxygen uptake in CDC-defined
CFS patients.