Background Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection can result in severe physiological impairments to cardiovascular and respiratory function. Further, a hallmark symptom of SARS‐CoV‐2 infection is shortness of breath, even at rest, which may be exaggerated during periods of exertion. However, the lasting effects of COVID‐19 on quantitative measures of exertional breathlessness in otherwise healthy individuals is unknown. Purpose The purpose of this study was to examine the sensory and affective dimensions of exertional dyspnea (i.e., shortness of breath during exercise) in otherwise healthy, young adults who had previously tested positive for SARS‐CoV‐2 over a period of three months. Methods Otherwise healthy, young adults (4M/3F, age: 21 ± 1 y, body mass index: 24.1±1.4 kgᐧm‐2, aerobic fitness: 35.7± 11.3 mL·kg‐1·min‐1) who tested positive for SARS‐CoV‐2 completed an incremental exercise test to voluntary exhaustion on a cycle ergometer three‐to‐four weeks after the positive SARS‐CoV‐2 test result (BL), as well as one and two months following baseline testing (1M and 2M, respectively). Subjective ratings of perceived breathlessness (RPB) and unpleasantness of breathing (RPU) were collected at rest and during each stage of exercise. Following exercise completion, subjects rated the unpleasantness and accompanying negative emotions (depression, anxiety, frustration, anger, and fear) associated with their exertional dyspnea using a visual analog scale (VAS). Results RPB at rest, during cycling at 60W, and at peak exercise were similar across visits (p > 0.05). RPB during cycling at 120W tended to decrease across time (BL: 2.9±0.9; 1M: 2.1±1.1; 2M: 2.0±1.4; p = 0.06). RPU at rest, during cycling at 60W, 120W, and at peak exercise were not different between visits (p > 0.05). VAS ratings of anxiety (BL: 1.8±2.1 cm; 1M: 3.1±3.2 cm; 2M: 0.8±0.7 cm; p = 0.05), but not those of depression, unpleasantness, anger, frustration, or fear differed across visits (p > 0.05). Conclusion These data suggest that the sensory dimension of exertional dyspnea during moderate intensity exercise improves (i.e., decreases) during recovery from SARS‐CoV‐2 infection. In contrast, the affective dimension of exertional dyspnea appears to be largely maintained throughout recovery, as only anxious emotions related to exertional dyspnea fluctuated over the three‐month time period.
Aging is an independent cardiovascular risk factor that exhibits impaired vascular function and aging itself is associated with a decline in nitric oxide (NO) bioavailability, an essential signaling molecule involved in vascular function. L‐Citrulline (L‐Cit) supplementation, and the subsequent conversion to L‐Arginine (L‐Arg), is an effective approach to augment substrate for endothelial NO production, potentially improving vascular function. However, the effect of L‐Cit supplementation in old adults is not well understood. Therefore, this study evaluated the effect of short‐term oral L‐Cit supplementation on flow mediated‐dilation (FMD) and reactive hyperemia, indicators of macro‐ and microvascular function, respectively. Eleven old adults (72±5 yrs) underwent 7‐day L‐Cit supplementation (6g per day). %FMD assessments were performed pre‐ and post‐L‐Cit supplementation in both the brachial (BA) and popliteal (PA) arteries in addition to the measurement of reactive hyperemia area under the curve (RH AUC) for 60s following FMD cuff release. Plasma L‐Cit and L‐Arg concentrations were measured to confirm L‐Cit absorption and conversion, respectively. The ratio of L‐Arg to plasma asymmetric dimethylarginine (ADMA) was calculated as a biomarker of NO‐bioavailability. L‐Cit supplementation improved plasma L‐Cit and L‐Arg concentrations (+269%; p=0.002; +74%; p=0.0008, respectively). Although plasma ADMA levels increased post‐treatment (0.51±0.02 vs 0.56±0.02uM/l, p=0.04), the L‐Arg/ADMA ratio was also significantly greater (273±30 vs 419±50; p=0.004). In contrast, there was no effect on either brachial or popliteal %FMD (BA 2.6±0.7 vs 3.4±0.7%; PA: 6.9±2.4 vs 6.6±2.0%, respectively) or RH AUC (BA: 537±124 vs 453±93ml; PA: 612±52 vs 706±81ml, respectively). In conclusion, despite the clear pharmacological efficacy of 7 days of L‐Cit supplementation, in terms of raising NO‐substrate bioavailability, neither macro‐ nor microvascular function was altered in old adults.
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