A statement from the Editor in Chief about this review and its planned update is available
here: www.cochrane.org/news/publication-cochrane-review-exercise-therapy-chronic-fatigue-syndrome
. Chronic fatigue syndrome (CFS) or myalgic encephalomyelitis (ME) is a serious disorder
characterised by persistent postexertional fatigue and substantial symptoms related
to cognitive, immune and autonomous dysfunction. There is no specific diagnostic test,
therefore diagnostic criteria are used to diagnose CFS. The prevalence of CFS varies
by type of diagnostic criteria used. Existing treatment strategies primarily aim to
relieve symptoms and improve function. One treatment option is exercise therapy. The
objective of this review was to determine the effects of exercise therapy for adults
with CFS compared with any other intervention or control on fatigue, adverse outcomes,
pain, physical functioning, quality of life, mood disorders, sleep, self‐perceived
changes in overall health, health service resources use and dropout. We searched the
Cochrane Common Mental Disorders Group controlled trials register, CENTRAL, and SPORTDiscus
up to May 2014, using a comprehensive list of free‐text terms for CFS and exercise.
We located unpublished and ongoing studies through the World Health Organization International
Clinical Trials Registry Platform up to May 2014. We screened reference lists of retrieved
articles and contacted experts in the field for additional studies. We included randomised
controlled trials (RCTs) about adults with a primary diagnosis of CFS, from all diagnostic
criteria, who were able to participate in exercise therapy. Two review authors independently
performed study selection, 'Risk of bias' assessments and data extraction. We combined
continuous measures of outcomes using mean differences (MDs) or standardised mean
differences (SMDs). To facilitate interpretation of SMDs, we re‐expressed SMD estimates
as MDs on more common measurement scales. We combined dichotomous outcomes using risk
ratios (RRs). We assessed the certainty of evidence using GRADE. We included eight
RCTs with data from 1518 participants. Exercise therapy lasted from 12 weeks to 26
weeks. The studies measured effect at the end of the treatment and at long‐term follow‐up,
after 50 weeks or 72 weeks. Seven studies used aerobic exercise therapies such as
walking, swimming, cycling or dancing, provided at mixed levels in terms of intensity
of the aerobic exercise from very low to quite rigorous, and one study used anaerobic
exercise. Control groups consisted of passive control, including treatment as usual,
relaxation or flexibility (eight studies); cognitive behavioural therapy (CBT) (two
studies); cognitive therapy (one study); supportive listening (one study); pacing
(one study); pharmacological treatment (one study) and combination treatment (one
study). Most studies had a low risk of selection bias. All had a high risk of performance
and detection bias. Exercise therapy compared with 'passive' control Exercise therapy
probably reduces fatigue at end of treatment (SMD −0.66, 95% CI −1.01 to −0.31; 7
studies, 840 participants; moderate‐certainty evidence; re‐expressed MD −3.4, 95%
CI −5.3 to −1.6; scale 0 to 33). We are uncertain if fatigue is reduced in the long
term because the certainty of the evidence is very low (SMD −0.62, 95 % CI −1.32 to
0.07; 4 studies, 670 participants; re‐expressed MD −3.2, 95% CI −6.9 to 0.4; scale
0 to 33). We are uncertain about the risk of serious adverse reactions because the
certainty of the evidence is very low (RR 0.99, 95% CI 0.14 to 6.97; 1 study, 319
participants). Exercise therapy may moderately improve physical functioning at end
of treatment, but the long‐term effect is uncertain because the certainty of the evidence
is very low. Exercise therapy may also slightly improve sleep at end of treatment
and at long term. The effect of exercise therapy on pain, quality of life and depression
is uncertain because evidence is missing or of very low certainty. Exercise therapy
compared with CBT Exercise therapy may make little or no difference to fatigue at
end of treatment (MD 0.20, 95% CI ‐1.49 to 1.89; 1 study, 298 participants; low‐certainty
evidence), or at long‐term follow‐up (SMD 0.07, 95% CI −0.13 to 0.28; 2 studies, 351
participants; moderate‐certainty evidence). We are uncertain about the risk of serious
adverse reactions because the certainty of the evidence is very low (RR 0.67, 95%
CI 0.11 to 3.96; 1 study, 321 participants). The available evidence suggests that
there may be little or no difference between exercise therapy and CBT in physical
functioning or sleep (low‐certainty evidence) and probably little or no difference
in the effect on depression (moderate‐certainty evidence). We are uncertain if exercise
therapy compared to CBT improves quality of life or reduces pain because the evidence
is of very low certainty. Exercise therapy compared with adaptive pacing Exercise
therapy may slightly reduce fatigue at end of treatment (MD −2.00, 95% CI −3.57 to
−0.43; scale 0 to 33; 1 study, 305 participants; low‐certainty evidence) and at long‐term
follow‐up (MD −2.50, 95% CI −4.16 to −0.84; scale 0 to 33; 1 study, 307 participants;
low‐certainty evidence). We are uncertain about the risk of serious adverse reactions
(RR 0.99, 95% CI 0.14 to 6.97; 1 study, 319 participants; very low‐certainty evidence).
The available evidence suggests that exercise therapy may slightly improve physical
functioning, depression and sleep compared to adaptive pacing (low‐certainty evidence).
No studies reported quality of life or pain. Exercise therapy compared with antidepressants
We are uncertain if exercise therapy, alone or in combination with antidepressants,
reduces fatigue and depression more than antidepressant alone, as the certainty of
the evidence is very low. The one included study did not report on adverse reactions,
pain, physical functioning, quality of life, sleep or long‐term results. Exercise
therapy probably has a positive effect on fatigue in adults with CFS compared to usual
care or passive therapies. The evidence regarding adverse effects is uncertain. Due
to limited evidence it is difficult to draw conclusions about the comparative effectiveness
of CBT, adaptive pacing or other interventions. All studies were conducted with outpatients
diagnosed with 1994 criteria of the Centers for Disease Control and Prevention or
the Oxford criteria, or both. Patients diagnosed using other criteria may experience
different effects. Exercise as treatment for adults with chronic fatigue syndrome
What is the aim of this review? People with chronic fatigue syndrome have long‐lasting
fatigue, joint pain, headaches, sleep problems, poor concentration and short‐term
memory. These symptoms cause significant disability and distress. We wanted to find
out whether exercise therapy can help people with chronic fatigue syndrome (myalgic
encephalomyelitis). Key messages People who have exercise therapy probably have less
fatigue at the end of treatment than those who receive more passive therapies. We
are uncertain if this improvement lasts in the long term. We are also uncertain about
the risk of serious side effects from exercise therapy. What was studied in the review?
We explored whether exercise therapy can reduce chronic fatigue syndrome symptoms.
We searched for studies comparing the effect of exercise therapy with treatment as
usual or other therapies. What are the main results of the review? We found eight
studies with 1518 participants. The studies compared participants who received exercise
therapy to participants who received treatment as usual or more active treatments
such as cognitive behavioural therapy. Participants had exercise therapy for 12 weeks
to 26 weeks. The studies measured the effect of the therapy at the end of the treatment
and also long term, after 50 or 72 weeks. Participants exercised at different levels
of intensity using variations of aerobic exercising such as walking, swimming or cycling.
Exercise therapy compared to treatment as usual or relaxation Participants who have
exercise therapy probably have less fatigue at the end of treatment, and they may
have moderately better physical functioning. We are uncertain if these improvements
last long term because we are very uncertain about the evidence. Participants who
have exercise therapy may have slightly better sleep, both at the end of treatment
and long term. We are uncertain about the risk of serious side effects and the effects
of exercise therapy on pain, quality of life, and depression. This is because we lack
evidence or because we are very uncertain about the evidence. Exercise therapy compared
to cognitive behavioural therapy Exercise therapy may make little or no difference
to participants’ fatigue at end of treatment or in the long term. Exercise therapy
may make little or no difference to participants’ physical functioning at end of treatment,
but the long‐term effect on physical functioning is uncertain. No studies looked at
the effect of exercise therapy on depression at the end of treatment, but it probably
has little or no long‐term effect. We are uncertain about the risk of side effects.
We are also uncertain about the effects on pain, quality of life, or sleep. This is
because we lack evidence or because we are very uncertain about the evidence. Exercise
therapy compared to adaptive pacing (living within limits) Participants who have exercise
therapy may have slightly less fatigue and depressive symptoms and slightly better
physical functioning and sleep at the end of treatment and long term than participants
who have adaptive pacing. We are uncertain about the risk of serious side effects.
We are also uncertain about the effect on quality of life or pain. This is because
we lack evidence or we are very uncertain about the evidence. Exercise therapy compared
to antidepressants We are uncertain if exercise therapy is better than antidepressants
at reducing fatigue. We are also uncertain of its effect on depression, side effects,
pain, physical functioning, quality of life or sleep. This is because we lack evidence
or we are very uncertain about the evidence. Why is this review important? Exercise
therapy is recommended by treatment guidelines and often used as treatment for people
with chronic fatigue syndrome. People with chronic fatigue syndrome should have the
opportunity to make informed decisions about their care and treatment based on robust
research evidence and whether exercise therapy is effective, either as a stand‐alone
intervention or as part of a treatment plan. It is important to note that the evidence
in this review is from people diagnosed with 1994 criteria of the Centers for Disease
Control and Prevention or the Oxford criteria. People diagnosed using other criteria
may experience different effects.