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Objective: It was hypothesized that the use of exercise limits prevents symptom increases and worsening of their health status following a walking exercise in people with chronic fatigue syndrome.

Design: An uncontrolled clinical trial (semi-experimental design).

Setting: Outpatient clinic of a university department.

,p>Subjects: Twenty-four patients with chronic fatigue syndrome.

Interventions: Subjects undertook a walking test with the two concurrent exercise limits. Each subject walked at an intensity where the maximum heart rate was determined by heart rate corresponding to the respiratory exchange ratio=1.0 derived from a previous submaximal exercise test and for a duration calculated from how long each patient felt they were able to walk.

Main outcome measures: The Short Form 36 Health Survey or SF-36, the Chronic Fatigue Syndrome Symptom List, and the Chronic Fatigue Syndrome - Activities and Participation Questionnaire were filled in prior to, immediately after and 24 hours after exercise.

Results: The fatigue increase observed immediately post-exercise (P=0.006) returned to pre-exercise levels 24 hours post-exercise. The increase in pain observed immediately post-exercise was retained at 24 hours post-exercise (P=0.03). Fourteen of the 24 subjects experienced a clinically meaningful change in bodily pain (change of SF-36 bodily pain score>=10); 6 indicated that the exercise bout had slightly worsened their health status, and 2 had a clinically meaningful decrease in vitality (change of SF-36 vitality score >=20). There was no change in activity imitations/participation restrictions.

Conclusion: It was shown that the use of exercise limits (limiting both the intensity and duration of exercise) prevents important health status changes following a walking exercise in people with chronic fatigue syndrome, but was unable to prevent short-term symptom increases. [Note: additionally, the authors noted that “The results for a minority of the subjects studied here support the notion that the exercise intensity necessary to cause a symptom increase can be quite mild…” that many subjects overestimated their exercise limits, and that study of other exercise limits to prevent worsening of ME/CFS symptoms & health status in response to exercise is warranted.]

Source: Clinical Rehabilitation, May 2008, 22(5), pp 426-435. PMID: 18441039, by Nijs J, Almond F, De Becker P, Truijen S, Paul L. Department of Human Physiology, Faculty of Physical Education and Physiotherapy, Vrije Universiteit Brussel. [E-mail: j.nijs@ha.be]