In this Issue
June 2016; volume 120, issue 11
- Transcutaneous electrical acupoint stimulation alleviates adverse cardiac remodeling induced by overload training in rats
Rigorous exercise may compromise heart function. Our study has found that overload training exercise in rats was associated with adverse cardiac remodeling and increased myocardial apoptosis, fibrosis, and autophagy. Transcutaneous electrical acupoint stimulation (TEAS), a traditional Chinese medical technique, could counteract the deleterious effects of overload training on the heart. These findings highlight the significance and potential applications of TEAS in preventing cardiac dysfunction induced by rigorous exercise.
- Intermittent severe hypoxia induces plasticity within serotonergic and catecholaminergic neurons in the neonatal rat ventrolateral medulla
Brain stem serotonin (5-HT) contributes to autoresuscitation during intermittent severe hypoxia (IsH). We demonstrate that 5-HT deficiency is associated with a greater, IsH-induced increase in Fos- and tyrosine hydroxylase-positive neurons. Irrespective of 5-HT content, IsH upregulated tryptophan hydroxylase 2 and 5-HT transporter expression. In 5-HT-deficient pups, the expression of 5-HT1A receptors and DOPA decarboxylase was decreased and increased, respectively, by IsH. The neonatal VLM exhibits significant serotonergic and catecholaminergic plasticity in response to IsH.
- Systolic-diastolic functional coupling in healthy children and in those with dilated cardiomyopathy
Systolic and diastolic function affect dilated cardiomyopathy (DCM) outcomes. However, systolic:diastolic (S:D) coupling, as a distinct characteristic, may itself affect function but is poorly characterized. Using tissue Doppler echocardiography, we found that S:D coupling becomes weaker in DCM with left ventricular remodeling and dysfunction and that the S:D coupling ratio may be useful to assess coupling, warranting study in relation to patient outcomes.
- A short period of high-intensity interval training improves skeletal muscle mitochondrial function and pulmonary oxygen uptake kinetics
The mechanism(s) facilitating pulmonary V̇o2 kinetics following a training intervention remains incompletely understood. Here we provide evidence that exercise training-induced improvement in skeletal muscle mitochondrial function coincides with concurrent improvements in pulmonary V̇o2 kinetics.
- Sucrose ingestion after exhaustive exercise accelerates liver, but not muscle glycogen repletion compared with glucose ingestion in trained athletes
This is the first study to assess both muscle and liver glycogen repletion postexercise after ingesting different types of carbohydrates in large amounts. We observed that sucrose ingestion accelerates postexercise liver glycogen repletion compared with glucose ingestion in spite of lower insulinemia and reduced gut discomfort. Therefore, when rapid recovery of endogenous carbohydrate stores is a goal, ingestion of sucrose at 1.5 g·kg−1·h−1 would be more appropriate than glucose.
- Chronic endurance exercise training offsets the age-related attenuation in contraction-induced rapid vasodilation
Aging is associated with attenuated exercise hyperemia and vasodilation. Chronic endurance exercise training augments exercise hyperemia and vasodilation during steady-state exercise in older adults. In the current study, we found that chronic exercise improves contraction-induced rapid vasodilation in both the arm and leg of older adults. Furthermore, our current results suggest that exercise capacity is associated with peak dilator responses in both the arm and leg of older adults.
- Effects of meal ingestion on blood pressure and regional hemodynamic responses after exercise
No study demonstrated the hemodynamic responses to meal ingestion during postexercise hypotension. This study investigated the combined effects of consuming a meal during postexercise hypotension on central and peripheral hemodynamics. Our results suggested that healthy subjects can suppress severe hypotension by vasoconstriction of the limbs even when a meal is ingested during postexercise hypotension. Our findings provide novel insight into the timing of exercise for the management of postprandial blood pressure in some individuals.
- Dilution space ratio of 2H and 18O of doubly labeled water method in humans
The doubly labeled water method is a precise method for measuring energy expenditure in free-living individuals. Its accuracy, however, is dependent on the ratio the relative dilution spaces of the two tracers. Herein we demonstrate that this ratio is not influenced by most subject characteristics and that a single constant can be used in most studies.
- Skeletal muscle phosphatidylcholine and phosphatidylethanolamine are related to insulin sensitivity and respond to acute exercise in humans
This article provides the first examination of skeletal muscle phosphatidylcholine-phosphatidylethanolamine (PC:PE) ratio at rest and in response to acute exercise in humans. In agreement with recent evidence in rodent models demonstrating a role for PC and PE in muscle metabolism, skeletal muscle PC:PE ratio was found to be inversely related to insulin sensitivity in obese individuals, adults with type 2 diabetes, and endurance-trained athletes; however, muscle PC:PE ratio was not altered in response to exercise.
- Training-specific functional, neural, and hypertrophic adaptations to explosive- vs. sustained-contraction strength training
Explosive-contraction strength training (ECT) denoted by brief contractions with high rate of torque development produced a wider range of functional adaptations than sustained-contraction strength training (SCT), with improvements in early- and late-phase explosive strength, as well as maximum strength. In contrast, SCT only improved maximum and late-phase explosive strength. The substantially lower loading duration of ECT (7% of SCT) makes this a less-demanding training modality compared with SCT, which may be preferentially tolerated by musculoskeletal patients.
- Accuracy and robustness of a simple algorithm to measure vessel diameter from B-mode ultrasound images
This study describes a relatively simple algorithm that accurately measures the diameter of arteries from B-mode images. The simplicity of the algorithm allows it to be easily modified for specific applications. Moreover, we apply use of digital reference objects (DROs) in place of physical phantoms. This allows the characteristics of the image to be manipulated, with precision, to determine the robustness of the algorithm.