Longitudinal Observations of Metabolic and Ventilatory Responses During Incremental Exercise in Young Adults Following SARS‐CoV‐2 Infection

Augenreich, Marc; Province, Valesha; Stute, Nina; Stickford, Abigail; Ratchford, Stephen; Stickford, Jonathon

BACKGROUND: The severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) targets organ angiotensin‐converting enzyme 2 receptors, and infection can lead to pulmonary and cardiovascular abnormalities. PURPOSE: To examine whether metabolic and cardiorespiratory responses during exercise were altered over a period of three months in young adults who previously tested positive for SARS‐CoV‐2. METHODS: A longitudinal analysis (n=7, 4M) was performed on young adults that tested positive for SARS‐CoV‐2 in the three‐to‐four weeks prior to data collection (BL), as well as once a month following baseline for two additional months (1M and 2M). Participants completed an incremental peak aerobic capacity test on a cycle ergometer. Metabolic and cardiorespiratory measurements were collected every minute using a metabolic cart. Measured variables included the following: ventilation (V̇(E)), tidal volume (V(T)), breathing frequency (f (B)), absolute and relative oxygen consumption (V̇O(2),), carbon dioxide production (V̇CO(2)), ventilatory efficiency (V̇(E)/V̇CO(2)), respiratory exchange ratio (RER), and heart rate (HR). Data were compared across visits at rest and during exercise at 60 W, 120 W, and peak exercise. Values are expressed as mean±SD. RESULTS: No differences were observed between visits in metabolic or cardiorespiratory variables at rest (p>0.05). There were no observed differences in most metabolic and cardiorespiratory variables during exercise at 60 W (p>0.05). However, V(T) during exercise at 60 W differed across visits (BL: 1.08 ± 0.19 L; 1M: 1.27 ± 0.27 L; 2M: 1.21 ± 0.25; p=0.007). No differences in any measure during exercise at 120 W were observed between visits. At peak exercise, V(T) was significantly different between visits (BL: 2.29 ± 0.42 L; 1M: 2.49 ± 0.54 L; 2M: 2.37 ± 0.51 L; p=0.033). Absolute and relative V̇O(2) between visits approached significance (p=0.055 and p=0.069, respectively), with lower peak oxygen consumption at baseline (2.60 ± 0.43 L·min(‐1), 35.7 ± 5.5 mL·kg(‐1)·min(‐1)) compared with follow up visits (1M: 2.84 ± 0.59 L·min(‐1), 38.8 ± 7.1 mL·kg(‐1)·min(‐1);2M: 2.72 ± 0.54 L·min(‐1), 37.3 ± 6.9 mL·kg(‐1)·min(‐1)). Ratings of perceived exertion were not different between visits at any exercise intensity (p>0.05). CONCLUSION: These data suggest that metabolic and cardiorespiratory responses at peak, but not submaximal, exercise may be limited acutely but that the decrement is recovered within two months following SARS‐CoV‐2 infection. We suspect that the changes observed in tidal volume between visits is related to the trend of greater peak metabolic work rates with time, despite no observed differences in minute ventilation.