Two-Day Cardiopulmonary Exercise Testing in Long COVID Post-Exertional Malaise Diagnosis

Background: Long COVID patients present with a myriad of symptoms that can include fatigue, exercise intolerance and post exertional malaise (PEM). Long COVID has been compared to other post viral syndromes, including myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), where a reduction in day 2 cardiopulmonary exercise test (CPET) performance of a two-day CPET protocol is suggested to be a result of PEM. We investigated cardiopulmonary and perceptual responses to a two-day CPET protocol in Long COVID patients.

Methods: 15 Long COVID patients [n=7 females; mean (SD) age: 53(11) yr; BMI = 32.2(8.5) kg/m²] performed a pulmonary function test and two ramp-incremental CPETs separated by 24hr. CPET variables included gas exchange threshold (GET), V̇O_2peak and WR_peak. Ratings of perceived dyspnoea and leg effort were recorded at peak exercise using the modified 0-10 Borg Scale. PEM (past six months) was assessed using the modified DePaul Symptom Questionnaire (mDSQ). One-sample t-tests were used to test significance of mean difference between days (p<0.05).

Results: mDSQ revealed PEM in 80% of patients. Lung function was normal. Responses to day 1 CPET were consistent with the presence of aerobic deconditioning in 40% of patients (V̇O_2peak <80% predicted, in the absence of evidence of cardiovascular and pulmonary limitations). There were no differences between day-1 and day-2 CPET responses (all p>0.05).

Conclusion: Post exertional malaise symptoms in Long COVID patients, in the absence of differences in two-day CPET responses separated by 24hours, suggests that post-exertional malaise is not due to impaired recovery of exercise capacity between days.

Source: Gattoni C, Abbasi A, Ferguson C, Lanks CW, Decato TW, Rossiter HB, Casaburi R, Stringer WW. Two-Day Cardiopulmonary Exercise Testing in Long COVID Post-Exertional Malaise Diagnosis. Respir Physiol Neurobiol. 2024 Oct 25:104362. doi: 10.1016/j.resp.2024.104362. Epub ahead of print. PMID: 39490617. https://www.sciencedirect.com/science/article/pii/S1569904824001551 (Full text)