Predictors of Submaximal Exercise Test Attainment in Adults Reporting Long COVID Symptoms, 2022, Romero-Ortuno et al

[Andy]

Abstract

Adults with long COVID often report intolerance to exercise. Cardiopulmonary exercise testing (CPET) has been used in many settings to measure exercise ability but has been conducted in a few long COVID cohorts. We conducted CPET in a sample of adults reporting long COVID symptoms using a submaximal cycle ergometer protocol.

We studied pre-exercise predictors of achieving 85% of the age-predicted maximum heart rate (85%HRmax) using logistic regression. Eighty participants were included (mean age 46 years, range 25–78, 71% women). Forty participants (50%) did not reach 85%HRmax. On average, non-achievers reached 84% of their predicted 85%HRmax. No adverse events occurred.

Participants who did not achieve 85%HRmax were older (p < 0.001), had more recent COVID-19 illness (p = 0.012) with higher frequency of hospitalization (p = 0.025), and had been more affected by dizziness (p = 0.041) and joint pain (p = 0.028). In the logistic regression model including age, body mass index, time since COVID-19, COVID-19-related hospitalization, dizziness, joint pain, pre-existing cardiopulmonary disease, and use of beta blockers, independent predictors of achieving 85%HRmax were younger age (p = 0.001) and longer time since COVID-19 (p = 0.008).

Our cross-sectional findings suggest that exercise tolerance in adults with long COVID has potential to improve over time. Longitudinal research should assess the extent to which this may occur and its mechanisms.

Open access, https://www.mdpi.com/2077-0383/11/9/2376/htm

 

[Hutan]

I don't think this tells us anything much, other than these researchers were ill-equipped to be carrying out CPET research on Long Covid cohorts.

The people included in the study almost certainly had a range of reasons for their reported fatigue and lingering symptoms, and there was no attempt to begin to identify them with, for example, lung function tests. While not discounting other possibilities, these researchers seem rather keen on an explanation of deconditioning that improves over time.

It has been proposed that long COVID may be a state of reduced fitness mainly caused by muscle deconditioning [9,10,11]. However, others have argued that the mechanisms of exercise intolerance after COVID-19 may be more complex and involve metabolic and cardiopulmonary pathways [12]. The extent to which post-COVID-19 exercise intolerance may improve over time is poorly understood.

Our research cannot shed light on the exact mechanisms responsible for the limited exercise tolerance in half of our sample; however, our observations are in keeping with the possibility that reduced fitness in long COVID may improve over time. To disentangle this complexity, longitudinal research with comprehensively characterized cohorts is warranted to see the extent to which drivers and fitness levels evolve over time in adults with long COVID. Indeed, CPET can be part of a diagnostic pathway and longitudinal follow up for long COVID patients

Chalder Fatigue Scale

Participants were also administered the 11-item Chalder Fatigue Scale (CFQ), a self-rating scale developed to measure the severity of physical and mental fatigue

There's no mention of PEM, or any reference to research on repeat CPETs. If a significant portion of the people tested experience PEM, then the particular result achieved in a single test says very little about their fitness levels. I don't see how participants could give informed consent if PEM was not discussed.

All participants gave their informed consent prior to their inclusion in the study.

They talk about the safety of their study and the lack of adverse events, and yet there was no monitoring of patients after the CPET.

Overall, the sample reported significant fatigue at baseline, with median CFQ score of 25 out of maximum of 33. Our study underscores both the feasibility and safety of our submaximal CPET protocol in this highly symptomatic sample including a wide age range (25–78), 18% prevalence of treated hypertension, 14% of pre-existing respiratory disease, and where 18% had been previously hospitalized for COVID-19.

No adverse events occurred.

I find the 'non-achievers' term rather offensive. They could have used 'people who did not achieve their predicted 85%HRmax' or the 'sub-85%HRmax cohort' rather than that term that suggests a much more global failure.

On average, non-achievers reached 84% of their predicted 85%HRmax.

The researchers probably did not mean to cause harm. I hope someone can contact these people at the School of Medicine, Trinity College Dublin, D02 R590 Dublin, Ireland and offer to help them learn what they need to know in order to be more effective investigators. @Tom Kindlon, @PhysiosforME