Sex differences in post-exercise fatigue and function in myalgic encephalomyelitis/chronic fatigue syndrome

Abstract

To assess biobehavioral sex differences in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) utilizing a low burden exercise protocol, 22 females and 15 males with ME/CFS and 14 healthy controls underwent two six-min walk tests. Fifteen daily assessments were scheduled for fatigue and function ratings and heart monitoring. Six-min walk tests were conducted on days 8 and 9. The ME/CFS group showed high self-report fatigue and impaired physical function, whereas healthy controls did not show fatigue or function abnormalities. In patients, no significant post-exercise changes were found for heart rate variability (HRV); however, heart rate decreased in ME/CFS males from Day 14 to Day 15 (p = 0.046). Female patients showed increased fatigue (p = 0.006) after the initial walk test, but a downward slope (p = 0.008) in fatigue following the second walk test. Male patients showed a decrease in self-report work limitation in the days after exercise (p = 0.046). The healthy control group evidenced a decrease in HRV after the walk tests from Day 9–14 (p = 0.038). This pilot study did not confirm hypotheses that females as compared to males would show slower exercise recovery on autonomic or self-report (e.g. fatigue) measures. A more exertion-sensitive test may be required to document prolonged post-exertional abnormalities in ME/CFS.Trial registration: NCT NCT03331419.

High proportions of post-exertional malaise and orthostatic intolerance in people living with post-COVID-19 condition: the PRIME post-COVID study

“…Other studies found that women more often had PEM and OI than men ( 11 , 14 ). As this was confirmed in our study population for PEM, subsequent analyses were stratified by sex.…”

“…PEM refers to the abnormal worsening of various symptoms (which can be fatigue) and loss of energy following minimal physical or cognitive stressors or other triggers that would have been tolerated normally before disease onset ( 6 ). PEM has been found to be more prevalent in women than in men ( 11 ), and infections can initiate PEM ( 12 ). Another comorbidity with ME/CFS is postural orthostatic tachycardia syndrome (POTS), which generally causes orthostatic intolerance ( 13 ).…”

Dysregulation of extracellular vesicle protein cargo in female myalgic encephalomyelitis/chronic fatigue syndrome cases and sedentary controls in response to maximal exercise

“…Another key limitation is that we only included females. While the majority of ME/CFS patients are female, there are also male patients and it cannot be assumed that these results would apply to males as well, as many sex differences have been documented (Friedberg et al., 2023 ; Germain et al., 2022 ). A third limitation is that this study is limited to patients that were physically able to complete the exercise protocol, so the most severe and disabled ME/CFS patients are not represented in our study population.…”

Disentangling the effects of PTSD from Gulf War Illness in male veterans via a systems-wide analysis of immune cell, cytokine, and symptom measures

“…Both maximal and submaximal exercise protocols have been used to determine behavioral and physiological consequences of acute exercise challenge in illnesses such as GWI, ME/CFS and long coronavirus disease [ 25 , 71 , 107 – 111 ]. Here we used exercise challenge to explore the consequences on GWI with and without PTSD symptomatology.…”