Indiana University researchers have discovered that women with long COVID experience heart rate irregularities in response to physical exertion, and this has the potential to constrain not only exercise tolerance but free-living physical activity.
o date, the implications of cardiopulmonary sequelae -persisting beyond acute illness- on physical function are largely unknown.
The study team characterized heart rate (HR) responses to and recovery from a 6-minute walk test (6MWT) in women ≈3 months following mild-to-moderate SARS-CoV-2 infection compared to non-infected controls.
A total of forty-five women (n = 29 SARS-CoV-2; n = 16 controls; age = 56 ± 11 years; body mass index = 25.8 ± 6.0 kg/m2) completed pulmonary function testing and a 6MWT.
The study findings showed that SARS-CoV-2 participants demonstrated reduced total lung capacity (84 ± 8 vs. 93 ± 13%; P = .006), vital capacity (87 ± 10 vs. 93 ± 10%; P = .040), functional residual capacity (75 ± 16 vs. 88 ± 16%; P = .006), and residual volume (76 ± 18 vs. 93 ± 22%; P = .001) compared to controls.
No between-group differences were observed in 6MWT distance (P = .194); however, the increase in HR with exertion was attenuated among SARS-CoV-2 participants compared to controls (+52 ± 20 bpm vs. +65 ± 18 bpm; P = .029). The decrease in HR was also delayed for minutes 1–5 of recovery among SARS-CoV-2 participants (all P < 0.05).
Women reporting specific symptoms at time of testing had greater impairments compared with controls and SARS-CoV-2 participants not actively experiencing these symptoms.
The study findings provide evidence for marked differences in chronotropic responses to and recovery from a 6MWT in women several months following acute SARS-CoV-2 infection.
The study findings were published in the peer reviewed The Physiological Society’s journal Experimental Physiology. https://physoc.onlinelibrary.wiley.com/doi/10.1113/EP089965
Over 225 million individuals have contracted acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for the coronavirus disease 2019 (COVID-19) pandemic. With progressive vaccination efforts, case incidence rates are declining; however, the functional consequences of cardiopulmonary sequelae persisting >3-4 weeks following the onset of initial symptoms, termed “post-acute COVID-19 syndrome” (Nalbandian et al., 2021), remain unclear.
Longitudinal monitoring of hospitalized SARS-CoV-2 patients has revealed restrictive defects and / or diffusion impairments in > 50% of patients in the months following discharge (Bellan et al., 2021; Orzes et al., 2021; Safont et al., 2021). Although male sex is recognized as a predictor for increased COVID-19 disease severity and mortality (Peckham et al., 2020), female sex has been associated with a greater risk for persistent diffusion impairments months into recovery (Bellan et al., 2021; Huang et al., 2021; Safont et al., 2021).
Additional data indicate that, following SARS-CoV-2 infection, women commonly report declining physical health or fatigue (Xiong et al., 2021) and are 3 to 4 times more likely to seek treatment for chronic symptoms (Davido, Seang, Tubiana, & de Truchis, 2020; Vanichkachorn et al., 2021). In particular, persistent cardiopulmonary abnormalities following a SARS-CoV-2 infection may reduce overall exercise tolerance in women.
The 6-minute walk test (6MWT) is a widely-used clinical assessment of functional exercise capacity (Lancaster, 2018); heart rate (HR) response to this test is a strong independent predictor of daily physical activity (Morita et al., 2018) and mortality (Holland et al., 2013; Swigris et al., 2009) in pulmonary disease patients.
However, it remains unclear whether chronotropic responses to a 6MWT are altered among women during post-acute recovery from COVID-19.
Therefore, the present work sought to characterize HR responses to and recovery from a 6MWT in women 4 weeks from a diagnosed SARS-CoV-2 infection compared to controls (i.e., no infection) matched for age and BMI.