Postexertional Symptom Exacerbation after Submaximal Exercise in Individuals with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Postacute Sequelae of COVID-19.

PURPOSE: In individuals with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and postacute sequelae of SARS-CoV-2 infection (PASC), physical activity can exacerbate symptoms for days to weeks, referred to as postexertional symptom exacerbation (PESE). This study characterized the trajectory of PESE symptoms before and for 7 d after a submaximal exercise task in individuals with ME/CFS or PASC.

METHODS

Individuals with ME/CFS ( n = 30) or PASC ( n = 30) and matched controls ( n = 30) were recruited from a university hospital and the community setting. Participants completed a 25-min moderate-intensity exercise on a whole-body cycle ergometer. The trajectory of eight commonly reported PESE symptoms (physical fatigue, mental fatigue, pain, physical function, flu-like symptoms, gastrointestinal symptoms, sleep dysfunction, and anxiety) before and for 7 d after exercise were analyzed.

RESULTS

There was variability in the proportion of those who experienced increased symptoms, ranging from 46/60 reporting physical fatigue to only 18/30 reporting anxiety. There was no change in any of the symptoms across the 7-d period when analyzed individually. An aggregate score of 4-5 symptoms that includes physical fatigue, mental fatigue, physical function, and flu-like symptoms, with or without pain, was more comprehensive in capturing maximal changes in PESE. Changes were greatest during the 72-h postexercise and for those with ME/CFS. The aggregate score shows that 8/30 of individuals with ME/CFS and 12/30 with PASC show minimal to no increase in PESE, while 6-7/30 show increases greater than 3/10 points.

CONCLUSIONS

PESE to a clinically relevant exercise task is variable in individuals with ME/CFS and PASC, as submaximal exercise does not exacerbate symptoms for some, while modifications of intensity may be necessary to minimize PESE in others.