Background & Aims

Individuals with Long COVID (LC) and myalgic encephalomyelitis (ME/CFS) report limitations with activity participation due to post-exertional malaise (PEM). PEM is characterized as increased pain, fatigue, and flu-like symptoms to physical activity, and is cited as a barrier by individuals with these conditions to participation in regular exercise.1-10 PEM to an acute exercise task11,12, also referred as exercise intolerance, presents as increases in symptoms that lasts for hours to weeks, interferes with daily activities and reduces quality of life.13-18 Despite the significant impact of PEM on quality of life, there has been limited investigation into baseline clinical phenotype and psychological factors that contribute to PEM in individuals with LC and ME/CFS. Understanding why some experience PEM while others do not could lead to improved exercise guidelines and novel strategies to address activity-induced pain and fatigue.19-21

Methods

Individuals with LC (n=30) and ME/CFS (n=30) completed validated measurements of fatigue, pain, PEM history, physical function, cognitive function, kinesiophobia, pain catastrophizing, depression, anxiety, quality of life, and physical activity. Participants performed a 25-minute exercise bout on a whole-body cycle ergometer and rated their fatigue, pain, and perceived exertion on a 0-10 numerical rating scale (NRS) throughout the task. Exercise intensity was guided using age-predicted maximal heart rate and symptom report during exercise. Participants rated aspects of PEM – physical fatigue, mental fatigue, pain, physical function, and flu-like symptoms – on a 0-10 NRS before and for seven days following the exercise task. PEM was measured as the sum of positive symptom changes following exercise (maximum score=50). Stepwise multiple linear regression examined relationships between baseline symptoms, psychological factors, and exercise related pain and fatigue on PEM.

Results

Individuals with LC (age: 44.1± 15.2, BMI: 28.9 ± 7.7) and ME/CFS (age: 43.2± 13.4, BMI: 28.8 ± 7.4) were of similar age and BMI. Both groups reported similar baseline fatigue severity (LC: 47.3 ± 11.2, ME/CFS: 51.8 ± 8.3) while the ME/CFS group reported greater pain severity (LC: 2.2 ± 1.4, ME/CFS: 3.3 ± 1.6) and PEM severity (LC: 7.2 ± 3.8, ME/CFS: 10.7 ± 3.6). When analyzing both cohorts, regression analysis was significant (R2=.359, p<.001) with baseline fatigue severity, depression, pain interference, and peak fatigue during exercise predicting peak PEM. Analyzing both cohorts separately, regression analysis was significant (R2=.484, p<.001) for LC with baseline fatigue severity, self-reported PEM, and widespread pain predicting peak PEM while no model was significant for ME/CFS due to limited correlation of baseline symptom profile and symptoms during exercise to PEM.

Conclusions

While individuals with LC and ME/CFS may present with similar symptom profiles their response to exercise may be attributable to unique factors. Notably, numerous baseline measures capturing fatigue, pain, PEM, physical function, cognitive function, physical activity, and psychological factors did not relate to the PEM reported in individuals with ME/CFS. While evaluation of baseline fatigue severity, self-reported PEM, and widespread pain may be pertinent factors in determining the response to exercise in individuals with LC. Further research is necessary to determine whether unique predictors of PEM exist in ME/CFS and whether predictive factors of PEM are valid, reliable, and sensitive to change. Investigation of biological mechanisms contributing to exercise-induced PEM in individuals with LC and ME/CFS may provide additional insight to activity-induced pain and fatigue.

References

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Presenting Author

Giovanni Berardi

Poster Authors

Giovanni Berardi

DPT, PhD

University of Iowa

Lead Author

Adam Janowski

DPT

Lead Author

Samuel McNally

BS

Lead Author

Alpana Garg

MD

Lead Author

Kathleen Sluka

PT

University of Iowa, Carver College of Medicine

Lead Author

Topics

  • Treatment/Management: Pharmacology: Psychological and Rehabilitative Therapies