Attenuating intrathoracic pressure swings decreases cardiac output at different intensities of exercise.

Intrathoracic pressure (ITP) swings that permit spontaneous ventilation have physiological implications for the heart. We sought to determine the effect of respiration on cardiac output ( ) during semi-supine cycle exercise using a proportional assist ventilator to minimize ITP changes and lower the work of breathing (W ). Twenty-four participants (12 females) completed three exercise trials at 30%, 60% and 80% peak power (W ) with unloaded (using a proportional assist ventilator, PAV) and spontaneous breathing.

Characterization of the Lower Airways and Oral Microbiota in Healthy Young Persons in the Community.

Lower airway dysbiosis contributes to disease pathogenesis in respiratory diseases. However, little is known regarding the microbiota of lower airways or the oral cavity of healthy young persons. To address this gap, 25 healthy persons (24.

The effect of proportional assist ventilation on the electrical activity of the human diaphragm during exercise.

New Findings: What is the central question of this study? What is the effect of lowering the normally occurring work of breathing on the electrical activity and pressure generated by the diaphragm during submaximal exercise in healthy humans? What is the main finding and its importance? Ventilatory assist during exercise elicits a proportional lowering of both the work performed by the diaphragm and diaphragm electrical activity. These findings have implications for exercise training studies using proportional assist ventilation to reduce diaphragm work in patients with cardiopulmonary disease.

Abstract: We hypothesized that when a proportional assist ventilator (PAV) is applied in order to reduce the pressure generated by the diaphragm, there would be a corresponding reduction in electrical activity of the diaphragm.

Therapeutic hypothermia attenuates physiologic, histologic, and metabolomic markers of injury in a porcine model of acute respiratory distress syndrome.

Acute respiratory distress syndrome (ARDS) is a lung injury characterized by noncardiogenic pulmonary edema and hypoxic respiratory failure. The purpose of this study was to investigate the effects of therapeutic hypothermia on short-term experimental ARDS. Twenty adult female Yorkshire pigs were divided into four groups (n = 5 each): normothermic control (C), normothermic injured (I), hypothermic control (HC), and hypothermic injured (HI).

Airway luminal area and the resistive work of breathing during exercise in healthy young females and males.

We examined the relationship between the work of breathing (W) during exercise and in vivo measures of airway size in healthy females and males. We hypothesized that sex differences in airway luminal area would explain the larger resistive W during exercise in females. Healthy participants ( = 11 females and = 11 males; 19-30 yr) completed a cycle exercise test to exhaustion where W was assessed using an esophageal balloon catheter.

Respiratory modulation of sympathetic vasomotor outflow during graded leg cycling.

Respiratory modulation of sympathetic vasomotor outflow to skeletal muscles (muscle sympathetic nerve activity; MSNA) occurs in resting humans. Specifically, MSNA is highest at end-expiration and lowest at end-inspiration during quiet, resting breathing. We tested the hypothesis that within-breath modulation of MSNA would be amplified during graded leg cycling.

Does competitive swimming affect lung growth?

Whether the large lungs of swimmers result from intensive training or genetic endowment has been widely debated. Given that peak lung growth velocities occur during puberty, this study examined if competitive swimming during puberty affected lung growth. Eleven- to fourteen-year-old healthy female competitive swimmers and controls were assessed before (PRE) and after (POST) one swimming season (7.

Ventilation and respiratory mechanics.

During dynamic exercise, the healthy pulmonary system faces several major challenges, including decreases in mixed venous oxygen content and increases in mixed venous carbon dioxide. As such, the ventilatory demand is increased, while the rising cardiac output means that blood will have considerably less time in the pulmonary capillaries to accomplish gas exchange. Blood gas homeostasis must be accomplished by precise regulation of alveolar ventilation via medullary neural networks and sensory reflex mechanisms.

Effects of 10 days of modest intermittent hypoxia on circulating measures of inflammation in healthy humans.

Purpose: Obstructive sleep apnea (OSA) is a common disease which is associated with elevated inflammatory markers and adhesion molecules, possibly due to nightly intermittent hypoxia (IH). The purpose of this study was to test the hypothesis that IH would increase systemic inflammatory markers in healthy human males.

Methods: Healthy, young male subjects (n = 9; 24 ± 2 years) were exposed to a single daily isocapnic hypoxia exposure (oxyhemoglobin saturation = 80%, 1 h/day) for 10 consecutive days.

Child obesity and fitness levels among Kenyan and Canadian children from urban and rural environments: a KIDS-CAN Research Alliance Study.

Objective: This study was designed to gather anthropometric and fitness-related data on Kenyan children living in urban (UKEN) and rural (RKEN) environments and to compare them with previous data collected on Canadian children in order to examine the potential nutrition-physical activity transition.

Methods: Height, weight, waist circumference, triceps skinfolds were directly measured on rural (RKEN) and urban Kenyan (UKEN) children (n = 179, 9-13 years) and compared with existing data from Canadian children living in urban and rural environments (n = 274, 9-13 years). Aerobic fitness was measured using the 20 m shuttle run, flexibility using the sit-and-reach test and isometric handgrip strength was assessed.

Control of ventilation in humans following intermittent hypoxia.

Exposure to chronic or intermittent hypoxia produces alterations in the ventilatory response to hypoxia. These adaptations can differ depending on the severity of the hypoxic stimulus, its duration, its pattern, and the presence or absence of other chemical stimuli. As such, there are significant differences between the responses to intermittent versus continuous hypoxia.

Cardiovascular responses to vibrostimulation for sperm retrieval in men with spinal cord injury.

Background/objective: Cardiovascular abnormalities and arrhythmias are common in individuals with spinal cord injury (SCI) who are undergoing vibrostimulation for sperm retrieval. The study aimed to examine cardiovascular control in men with SCI undergoing this procedure.

Methods: Individuals with chronic cervical (n=8; age: 33.