This study was the first to investigate the vascular implications of contracting SARS-CoV-2 among young, otherwise healthy adults. Using a cross-sectional design, this study assessed vascular function 3–4 wk after young adults tested positive for SARS-CoV-2. The main findings from this study were a strikingly lower vascular function and a higher arterial stiffness compared with healthy controls. Together, these results suggest rampant vascular effects seen weeks after contracting SARS-CoV-2 in young adults.

 The impact of SARS-CoV-2 infection on autonomic and cardiovascular function in otherwise healthy individuals is unknown. We show for the first time that young adults recovering from SARS-CoV-2 have elevated resting sympathetic activity, but similar heart rate and blood pressure, compared with control subjects. Survivors of SARS-CoV-2 also exhibit suppressed sympathetic nerve activity and pain perception during a cold pressor test compared with healthy controls.  Further, these individuals display higher sympathetic nerve activity throughout an orthostatic challenge, as well as an exaggerated heart rate response to orthostasis. If similar autonomic dysregulation, like that found here in young individuals, is present in older adults following SARS-CoV-2 infection, there may be substantial adverse implications for cardiovascular health.

Contracting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been observed to cause decrements in vascular function of young adults. However, less is known about the impact of SARS-CoV-2 on arterial stiffness and structure, which might have additional implications for cardiovascular health. The purpose of this study was to assess the carotid artery stiffness and structure using ultrasound and the aortic augmentation index (AIx) using applanation tonometry in young adults after they tested positive for SARS-CoV-2. We hypothesized that carotid artery stiffness, carotid intima-media thickness (cIMT) and aortic AIx would be elevated in young adults with SARS-CoV-2 compared with healthy young adults. We evaluated 15 young adults (six male and nine female; 20 ± 1 years of age; body mass index, 24 ± 3 kg m −2 ) 3-4 weeks after a positive SARS-CoV-2 test result compared with young healthy adults (five male and 10 female; 23 ± 1 years of age; body mass index, 22 ± 2 kg m −2 ) who were evaluated before the coronavirus 2019 pandemic. Carotid stiffness, Young's modulus and cIMT were assessed using ultrasound, whereas aortic AIx and aortic AIx standardized to 75 beats min −1 (AIx@HR75) were assessed from carotid pulse wave analysis using SphygmoCor. Group differences were observed for carotid stiffness (control, 5 ± 1 m s −1 ; SARS-CoV-2, 6 ± 1 m s −1 ), Young's modulus (control, 396 ± 120 kPa; SARS-CoV-2, 576 ± 224 kPa), aortic AIx (control, 3 ± 13%; SARS-CoV-2, 13 ± 9%) and aortic AIx@HR75 (control, −3 ± 16%; SARS-CoV-2, 10 ± 7%; P < 0.05). However, cIMT was similar between groups (control, 0.42 ± 0.06 mm; SARS-CoV-2, 0.44 ± 0.08 mm; P > 0.05). This cross-sectional analysis revealed higher carotid artery stiffness and aortic stiffness among young adults with SARS-CoV-2.These results provide further evidence of cardiovascular impairments among young adults recovering from SARS-CoV-2 infection, which should be considered for cardiovascular complications associated with SARS-CoV-2.

The efficacy of and mechanisms behind the widespread use of lower-leg compression as an ergogenic aid to improve running performance are unknown. The purpose of this study was to examine whether wearing graduated lower-leg compression sleeves during exercise evokes changes in running economy (RE), perhaps due to altered gait mechanics. Sixteen highly trained male distance runners completed 2 separate RE tests during a single laboratory session, including a randomized-treatment trial of graduated calf-compression sleeves (CS; 15-20 mm Hg) and a control trial (CON) without compression sleeves. RE was determined by measuring oxygen consumption at 3 constant submaximal speeds of 233, 268, and 300 m/min on a treadmill. Running mechanics were measured during the last 30 s of each 4-min stage of the RE test via wireless triaxial 10-g accelerometer devices attached to the top of each shoe. Ground-contact time, swing time, step frequency, and step length were determined from accelerometric output corresponding to foot-strike and toe-off events. Gait variability was calculated as the standard deviation of a given gait variable for an individual during the last 30 s of each stage. There were no differences in VO2 or kinematic variables between CON and CS trials at any of the speeds. Wearing lower-leg compression does not alter the energetics of running at submaximal speeds through changes in running mechanics or other means. However, it appears that the individual response to wearing lower-leg compression varies greatly and warrants further examination.

Thirteen patients with implanted Heartmate II CF-LVADs were recruited from the University of Texas Southwestern Medical Center advanced heart failure (HF)/mechanical circulatory support Background-Current-generation left ventricular assist devices provide circulatory support that is minimally or entirely nonpulsatile and are associated with marked increases in muscle sympathetic nerve activity (MSNA), likely through a baroreceptor-mediated pathway. We sought to determine whether the restoration of pulsatile flow through modulations in pump speed would reduce MSNA through the arterial baroreceptor reflex. Methods and Results-Ten men and 3 women (54±14 years) with Heartmate II continuous-flow left ventricular assist devices underwent hemodynamic and sympathetic neural assessment. Beat-to-beat blood pressure, carotid ultrasonography at the level of the arterial baroreceptors, and MSNA via microneurography were continuously recorded to determine steady-state responses to step changes (200-400 revolutions per minute) in continuous-flow left ventricular assist device pump speed from a maximum of 10 480±315 revolutions per minute to a minimum of 8500±380 revolutions per minute. Reductions in pump speed led to increases in pulse pressure (high versus low speed: 17±7 versus 26±12 mm Hg; P<0.01), distension of the carotid artery, and carotid arterial wall tension (P<0.05 for all measures). In addition, MSNA was reduced (high versus low speed: 41±15 versus 33±16 bursts per minute; P<0.01) despite a reduction in mean arterial pressure and was inversely related to pulse pressure (P=0.037). Conclusions-Among subjects with continuous-flow left ventricular assist devices, the restoration of pulsatile flow through modulations in pump speed leads to increased distortion of the arterial baroreceptors with a subsequent decline in MSNA. Additional study is needed to determine whether reduction of MSNA in this setting leads to improved outcomes.

Corin (an atrial natriuretic peptide converting enzyme) represents a potential biomarker for gestational hypertensive disorders; yet, its role in blood pressure regulation throughout pregnancy remains unclear. We investigated the time-course of change in blood corin content in relation to blood pressure and sympathetic nerve activity throughout pregnancy. Forty-four women (29±0.9 yrs) participated. Following-term, 23 had 'low-risk' (no personal history of gestational hypertensive disorders) normal pregnancies, 13 had 'high-risk' (personal history of gestational hypertensive disorders) normal pregnancies, and eight developed gestational hypertension. Blood pressure, heart rate, muscle sympathetic nerve activity, and serum corin were measured prior-to pregnancy, during early-(4-8 wks) and late-pregnancy (32-36 wks), and post-partum (6-10 wks). Overall, compared to pre-pregnancy, corin remained unchanged during early-pregnancy, increased markedly during late-pregnancy (P<0.001), and returned to pre-pregnancy levels post-partum. In women who developed gestational hypertension, the change in corin from early-to late-pregnancy was greater than those with 'low-risk' normal pregnancies (Δ971±134 vs. Δ486±79 pg/mL; P<0.05). Throughout pregnancy, blood pressure and muscle sympathetic nerve activity were augmented in women with gestational hypertension (all P<0.05). Finally, changes in corin from early-to late-pregnancy were related to all indices of blood pressure (R=0.454-0.551; all P<0.01) in late-pregnancy, whereas burst frequency, burst incidence, and total muscle sympathetic nerve activity (R=0.576-0.614; all P<0.001) in early-pregnancy were related to changes in corin from early-to late-pregnancy. Corin plays a unique role in blood pressure regulation throughout

While a number of published studies exist to guide endurance athletes with the best practices regarding implementation of altitude training, a key unanswered question concerns the proper timing of return to sea level prior to major competitions. Evidence reviewed here suggests that, altogether, the deacclimatization responses of hematological, ventilatory, and biomechanical factors with return to sea level likely interact to determine the best timing for competitive performance.

To best sustain endurance activity, two systems must be effectively coordinated: ventilation and locomotion. Evidence has long suggested that these two mammalian rhythms are linked, yet determinants and implications of locomotor-respiratory coupling (LRC) continue to be investigated. Two general areas explaining the potential mechanisms underlying LRC are (1) neural interactions between central and peripheral controllers of locomotion and respiration, and (2) mechanical interactions between locomotor dynamics and respiratory mechanics. Additional suggested explanations for/consequence of the existence of LRC in mammals include an improved energetic cost of locomotion and a reduced sensation of breathlessness. As such, any perturbation to LRC, via alterations in breathing or kinematic patterns, could have negative performance implications to both athlete and patient populations.