Impacts of the first wave of the COVID-19 pandemic on leisure and transportation physical activity among healthcare workers.

Introduction: The COVID-19 pandemic may lead to reduced physical activity (PA) in health care workers (HCWs). Objective: To evaluate leisure and transport-related PA in HCW of a COVID-19-dedicated hospital during the first wave of the COVID-19 pandemic. Methods: This is a cross-sectional study with a sample of 1,527 HCWs. Socioeconomic aspects, occupational characteristics, and engagement in leisure and transport-related PA were investigated through an online survey administered in August of 2020. Results: More than 80 % HCWs performed < 150 min/week of leisure-related PA, and 85 % performed ≤ 30 min/day transport-related PA. Being male was associated with more PA (OR: 1.93; 95 % CI:1.40-2.66) and transport-related PA; working in nursing, physical therapy, and cleaning/housekeeping services was associated with low PA (OR: 0.70; 95 % CI:0.51-0.95). Physicians and administrative staff were less active in transport-related PA. Conclusions: HCWs working in a COVID-19 hospital had low levels of PA in the domains of leisure and transportation.

Thyroid hormone induces restrictive cardiomyopathy in ß1-adrenoceptor knockout mice.

The purpose of this study was to characterize the role of ß1-AR signaling and its cross-talk between cardiac renin-angiotensin system and thyroid-hormone-induced cardiac hypertrophy. T3 was administered at 0.5 mg·kg-1·day-1 for 10 days in ß1-KOT3 and WTT3 groups, while control groups received vehicle alone. Echocardiography and myocardial histology was performed; cardiac and serum ANGI/ANGII and ANP and cardiac levels of p-PKA, p-ERK1/2, p-p38-MAPK, p-AKT, p-4EBP1, and ACE were measured. WTT3 showed decreased IVSTd and increased LVEDD versus WTsal (p < 0.05). ß1-KOT3 exhibited lower LVEDD and higher relative IVSTd versus ß1-KOsal, the lowest levels of ejection fraction, and the highest levels of cardiomyocyte diameter (p < 0.05). Cardiac ANP levels decreased in WTT3 versus ß1-KOT3 (p < 0.05). Cardiac ACE expression was increased in T3-treated groups (p < 0.05). Phosphorylated-p38 MAPK levels were higher in WTT3 versus WTsal or ß1-KOT3, p-4EBP1 was elevated in ß1-KO animals, and p-ERK1/2 was up-regulated in ß1-KOT3. These findings suggest that ß1-AR signaling is crucial for TiCH.

ß2-Adrenergic Signaling Modulates Mitochondrial Function and Morphology in Skeletal Muscle in Response to Aerobic Exercise.

The molecular mechanisms underlying skeletal muscle mitochondrial adaptations induced by aerobic exercise (AE) are not fully understood. We have previously shown that AE induces mitochondrial adaptations in cardiac muscle, mediated by sympathetic stimulation. Since direct sympathetic innervation of neuromuscular junctions influences skeletal muscle homeostasis, we tested the hypothesis that ß2-adrenergic receptor (ß2-AR)-mediated sympathetic activation induces mitochondrial adaptations to AE in skeletal muscle. Male FVB mice were subjected to a single bout of AE on a treadmill (80% Vmax, 60 min) under ß2-AR blockade with ICI 118,551 (ICI) or vehicle, and parameters of mitochondrial function and morphology/dynamics were evaluated. An acute bout of AE significantly increased maximal mitochondrial respiration in tibialis anterior (TA) isolated fiber bundles, which was prevented by ß2-AR blockade. This increased mitochondrial function after AE was accompanied by a change in mitochondrial morphology towards fusion, associated with increased Mfn1 protein expression and activity. ß2-AR blockade fully prevented the increase in Mfn1 activity and reduced mitochondrial elongation. To determine the mechanisms involved in mitochondrial modulation by ß2-AR activation in skeletal muscle during AE, we used C2C12 myotubes, treated with the non-selective ß-AR agonist isoproterenol (ISO) in the presence of the specific ß2-AR antagonist ICI or during protein kinase A (PKA) and Gαi protein blockade. Our in vitro data show that ß-AR activation significantly increases mitochondrial respiration in myotubes, and this response was dependent on ß2-AR activation through a Gαs-PKA signaling cascade. In conclusion, we provide evidence for AE-induced ß2-AR activation as a major mechanism leading to alterations in mitochondria function and morphology/dynamics. ß2-AR signaling is thus a key-signaling pathway that contributes to skeletal muscle plasticity in response to exercise.