Cardiopulmonary Exercise Testing in patients with Long COVID: Evaluating functional capacity and exercise limitations, Sperling et al, 2024

John Mac

Senior Member (Voting Rights)
Abstract
BACKGROUND
Following COVID-19, some patients present with ongoing symptoms like breathlessness and exercise limitations, even after mild acute infection.

Research Question
What is the exercise capacity of patients diagnosed with long COVID and does it change from baseline to the 1-year follow-up?

STUDY DESIGN AND METHODS
This retrospective case series included patients with persistent symptoms following a confirmed diagnosis of COVID-19. Exercise capacity was examined by cardiopulmonary exercise testing (CPET) and parameters related to performance, ventilation, circulation and gas exchange were compared to predicted values. A subgroup of patients was retested one year after baseline and self-reported physical fitness was assessed at follow-up.

RESULTS
In total, 169 patients completed baseline CPET and 41 patients 1-year follow-up. Mean maximum workload was 172 watts (95% CI 161; 182), with 19% not achieving at least 84% predicted workload. Mean VO2 peak (ml/kg/min) was 24.4 (95% CI 23.1;25.7), and 36% had a value below % predicted. VO2/workload slope below normal threshold of 8.4 ml/min/watt was observed in 54% of patients. The 1-year follow-up results showed no statistically changes in any of the CPET parameters which correspond to lack of improvement in self-reported physical fitness.

INTERPRETATION
Patients with long COVID demonstrated lowered VO2 peak, VO2/workload slope and/or VE/VCO2 but different parameters were lowered in different patients illustrating a heterogeneous study population. No improvements in any parameters were found at 1-year follow-up.

https://www.sciencedirect.com/science/article/pii/S2949789224000023
 
A considerable overlap between long COVID and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) has been increasingly recognized. The exercise intolerance reported in this study share similarities with hemodynamic and gas exchange disturbances observed in patients with ME/CFS, suggesting the presence of common mechanisms.

At baseline, patients were advised to be physically active at as high an intensity level as possible and gradually return to usual sports activities. The 1-year follow-up results showed no statistically changes in any of the CPET parameters which correspond to lack of improvement in self-reported physical fitness. Prior to infection, patients reported a higher level of physical activity and physical fitness than the general population and may have experienced exercise limitations as more disruptive than more inactive individuals.
 
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