IMAGE DESCRIPTION: An image of a person with ME/CFS taken from our library of real people with ME. The title reads: Recovery from Exercise in Persons with ME/CFS. With an overlay of a screenshot of a diagram of the CPET results from the research paper. The ME Association logo (bottom right)

Research: Recovery from Exercise in Persons with ME/CFS

Multidisciplinary Digital Publishing Institute (MPDI) have published the following research ‘Recovery from Exercise in Persons with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS)' which involved cardiopulmonary exercise testing (CPET) to assess the severity of post-exertional malaise (PEM).


Background and Objectives:

Post-exertional malaise (PEM) is the hallmark of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), but there has been little effort to quantitate the duration of PEM symptoms following a known exertional stressor. Using a Symptom Severity Scale (SSS) that includes nine common symptoms of ME/CFS, we sought to characterize the duration and severity of PEM symptoms following two cardiopulmonary exercise tests separated by 24 h (2-day CPET).

Materials and Methods:

Eighty persons with ME/CFS and 64 controls (CTL) underwent a 2-day CPET. ME/CFS subjects met the Canadian Clinical Criteria for diagnosis of ME/CFS; controls were healthy but not participating in regular physical activity. All subjects who met maximal effort criteria on both CPETs were included. SSS scores were obtained at baseline, immediately prior to both CPETs, the day after the second CPET, and every two days after the CPET-1 for 10 days. Results: There was a highly significant difference in judged recovery time (ME/CFS = 12.7 ± 1.2 d; CTL = 2.1 ± 0.2 d, mean ± s.e.m., Chi2 = 90.1, p < 0.0001). The range of ME/CFS patient recovery was 1–64 days, while the range in CTL was 1–10 days; one subject with ME/CFS had not recovered after one year and was not included in the analysis. Less than 10% of subjects with ME/CFS took more than three weeks to recover. There was no difference in recovery time based on the level of pre-test symptoms prior to CPET-1 (F = 1.12, p = 0.33). Mean SSS scores at baseline were significantly higher than at pre-CPET-1 (5.70 ± 0.16 vs. 4.02 ± 0.18, p < 0.0001). Pharmacokinetic models showed an extremely prolonged decay of the PEM response (Chi2 > 22, p < 0.0001) to the 2-day CPET.


ME/CFS subjects took an average of about two weeks to recover from a 2-day CPET, whereas sedentary controls needed only two days. These data quantitate the prolonged recovery time in ME/CFS and improve the ability to obtain well-informed consent prior to doing exercise testing in persons with ME/CFS. Quantitative monitoring of PEM symptoms may provide a method to help manage PEM.

ME Association Comment

“Although most people with ME/CFS do not have access to cardiopulmonary exercise testing (CPET) to help with either diagnosis or management, we know from patient evidence that this procedure can (not surprisingly) cause an exacerbation of symptoms, and sometimes a more prolonged relapse.

“This is a useful item of research which demonstrates that, on average, people with ME/CFS take about 2 weeks to recover from a 2-day CPET.

“More information on the use of CPET in ME/CFS can be found in the Investigation section of the ME Association's ME/CFS/PVFS Clinical & Research Guide 2022 Edition (also known as the ‘purple book').”

ME Association ME/CFS/PVFS Clinical & Research Guide (2022 Edition)

Dr Charles Shepherd,
Trustee and
Hon. Medical Adviser
to the ME Association.
Member of the 2018-2021 NICE Guideline Committee.
Member of the 2002 Independent Working Group on ME/CFS.

Dr Charles Shepherd
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