Locomotor-Respiratory Coupling Is Maintained In Simulated Moderate Altitude In Trained Distance Runners

To determine whether acute exposure to simulated moderate altitude alters locomotor-respiratory coupling (LRC) patterns in runners, 13 trained male distance runners performed a running economy and maximal oxygen uptake (Vo2max) test in normoxia (NORM) and hypoxia (HYP) (FIO2= 15.8%; ~2,400 m/8,000 ft) on separate days. Running economy (RE), the degree of LRC, stride frequency-to-breathing frequency quotients (SF/fb), ratings of perceived exertion (RPE), and dyspnea were assessed at three common submaximal speeds and Vo2max. SF/fb were significantly lower at each submaximal speed in HYP (12.9 km/h: 2.91 ± 0.20 vs. 2.45 ± 0.17, 14.3 km/h: 2.53 ± 0.17 vs. 2.21 ± 0.14, 16.1 km/h: 2.22 ± 0.14 vs. 1.95 ± 0.09; P < 0.05). The degree of LRC (range: 36–99%) in HYP was not significantly different than NORM at any of the three common submaximal speeds. However, the degree of LRC was significantly higher at Vo2max in HYP than NORM (43.8 ± 3.4% vs. 57.1 ± 3.8%; P < 0.05). RE and RPE were similar at all running speeds. Dyspnea was significantly greater in HYP compared with NORM at 16.1 km/h (P < 0.05). Trained distance runners are able to maintain LRC in HYP, despite increases in breathing frequency. Within this unique population, years of training may enhance and optimize the ability to maintain LRC to minimize metabolic costs and dyspnea

Role Of Corin In Blood Pressure Regulation In Normotensive And Hypertensive Pregnancy

Corin (an atrial natriuretic peptide–converting enzyme) represents a potential biomarker for gestational hypertensive disorders; yet, its role in blood pressure (BP) regulation throughout pregnancy remains unclear. We investigated the time course of change in blood corin content in relation to BP and sympathetic nerve activity throughout pregnancy. Forty-four women (29±0.9 years) 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 8 developed gestational hypertension. BP, heart rate, muscle sympathetic nerve activity, and serum corin were measured before pregnancy, during early (4–8 weeks) and late pregnancy (32–36 weeks), and postpartum (6–10 weeks). Overall, compared with prepregnancy, corin remained unchanged during early pregnancy, increased markedly during late pregnancy (P<0.001), and returned to prepregnancy levels postpartum. In women who developed gestational hypertension, the change in corin from early to late pregnancy was greater than those with low-risk normal pregnancies (?971±134 versus ?486±79 pg/mL; P<0.05). Throughout pregnancy, BP 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 BP (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 BP regulation throughout normotensive and, especially, hypertensive pregnancy and may represent a promising biomarker for determining women at high risk of adverse pregnancy outcome

Tracking peripheral vascular function for six months in young adults following SARS‐CoV‐2 infection

Abstract SARS‐CoV‐2 infection is known to instigate a range of physiologic perturbations, including vascular dysfunction. However, little work has concluded how long these effects may last, especially among young adults with mild symptoms. To determine potential recovery from acute vascular dysfunction in young adults (8 M/8F, 21 ± 1 yr, 23.5 ± 3.1 kg⋅m−2), we longitudinally tracked brachial artery flow‐mediated dilation (FMD) and reactive hyperemia (RH) in the arm and hyperemic response to passive limb movement (PLM) in the leg, with Doppler ultrasound, as well as circulating biomarkers of inflammation (interleukin‐6, C‐reactive protein), oxidative stress (thiobarbituric acid reactive substances, protein carbonyl), antioxidant capacity (superoxide dismutase), and nitric oxide bioavailability (nitrite) monthly for a 6‐month period post‐SARS‐CoV‐2 infection. FMD, as a marker of macrovascular function, improved from month 1 (3.06 ± 1.39%) to month 6 (6.60 ± 2.07%; p  0.05). Circulating markers of inflammation, oxidative stress, antioxidant capacity, and nitric oxide bioavailability did not change during the 6 months (p > 0.05). Together, these results suggest some improvements in macrovascular, but not microvascular function, over 6 months following SARS‐CoV‐2 infection. The data also suggest persistent ramifications for cardiovascular health among those recovering from mild illness and among young, otherwise healthy adults with SARS‐CoV‐2

Monthly transthoracic echocardiography in young adults for 6 months following SARS‐CoV‐2 infection

Abstract Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) can elicit acute and long‐term effects on the myocardium among survivors, yet effects among otherwise healthy young adults remains unclear. Young adults with mild symptoms of SARS‐CoV‐2 (8M/8F, age: 21 ± 1 years, BMI: 23.5 ± 3.1 kg·m−2) underwent monthly transthoracic echocardiography (TTE) and testing of circulating cardiac troponin‐I for months 1–6 (M1–M6) following a positive polymerase chain reaction test to better understand the acute effects and post‐acute sequelae of SARS‐CoV‐2 on cardiac structure and function. Left heart structure and ejection fraction were unaltered from M1–M6 (p > 0.05). While most parameters of septal and lateral wall velocities, mitral and tricuspid valve, and pulmonary vein (PV) were unaltered from M1–M6 (p > 0.05), lateral wall s′ wave velocity increased (M1: 0.113 ± 0.019 m·s−1, M6: 0.135 ± 0.022 m·s−1, p = 0.013); PV S wave velocity increased (M1: 0.596 ± 0.099 m·s−1, M6: 0.824 ± 0.118 m·s−1, p < 0.001); the difference between PV A wave and mitral valve (MV) A wave durations decreased (M1: 39.139 ± 43.715 ms, M6: 18.037 ± 7.227 ms, p = 0.002); the ratio of PV A duration to MV A duration increased (M1: 0.844 ± 0.205, M6: 1.013 ± 0.132, p = 0.013); and cardiac troponin‐I levels decreased (M1: 0.38 ± 0.20 ng·ml−1, M3: 0.28 ± 0.34 ng·ml−1, M6: 0.29 ± 0.16 ng·ml−1; p = 0.002) over time. While young adults with mild symptoms of SARS‐CoV‐2 lacked changes to cardiac structure, the subclinical improvements to cardiac function and reduced inflammatory marker of cardiac troponin‐I over 6 months following SARS‐CoV‐2 infection provide physiologic guidance to post‐acute sequelae and recovery from SARS‐CoV‐2 and its variants using conventional TTE