Prediction of peak oxygen uptake in Chronic Fatigue Syndrome (CFS)

OBJECTIVES: To establish a simple, valid, and acceptable

method of predicting peak oxygen uptake (VO2peak) in patients

with chronic fatigue syndrome (CFS), which could provide a

basis for subsequent exercise prescription at an appropriate

intensity as part of a clinical rehabilitation programme.

METHODS: A total of 130 patients who met UK research criteria

for CFS were taken from consecutive referrals for chronic

fatigue to the University Department of Medicine at Withington

Hospital, Manchester. VO2peak was determined using an

incremental graded exercise test to exhaustion. Respiratory

gas exchange, work rate, and heart rate were monitored


RESULTS: In all patients, VO2peak was found to

correlate strongly and significantly with peak work rate

(WRpeak) during testing (r2 = 0.88, p<0.001). In patients who

exercised for longer than two minutes (n = 119), regression

analysis established the relation as Vo2peak = 13.1 x WRPpeak

+ 284, where VO2 is given in ml/min and WR in W. The mean

error between the measured VO2peak and the predicted value was

10.7%. The relation between increase in work rate and oxygen

uptake across the group was highly significant (r2 = 0.87,

p<0.001), and given as VO2increase = 12.0 x WRincrease, this

value being similar to that expected for healthy individuals.

Almost all (97%) subjects reported no exacerbation of symptoms

after maximal exercise testing.

CONCLUSIONS: Using a simple to

administer maximal exercise test on a cycle ergometer, it is

possible to predict accurately the VO2peak of a patient with

CFS from peak work rate alone. This value can then be used as

an aid to setting appropriate exercise intensity for a

rehabilitation programme. The increase in VO2 per unit

increase in workload was consistent with that expected in

healthy individuals, suggesting that the physiological

response of the patients measured here was not abnormal.

Contrary to the belief of many patients, maximal exercise

testing to the point of subjective exhaustion proved to be

harmless, with no subjects suffering any lasting deterioration

in their condition after assessment.

Mullis R, Campbell IT, Wearden AJ, Morriss RK, Pearson DJ

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