The ventilatory response to sine wave variation in exercise loads and limb movement frequency.

The current study's experiments tested the hypothesis that limb movement frequency is a significant determinant of exercise hyperpnoea. To this end, 19 healthy participants walked on a treadmill, where work was varied sinusiodally by alterations in either treadmill speed or grade. Measured responses were fitted with sine waves to determine their amplitudes and phase angles.

Long-term facilitation of breathing is absent after episodes of hypercapnic hypoxia in awake humans.

Despite the failure by many previous investigators to demonstrate a long-term facilitation of breathing following episodes of hypoxia in awake humans, we attempted to produce it using a pattern of hypercapnic hypoxic episodes similar to that experienced by obstructive sleep apnoea patients, reasoning that if long-term facilitation was relevant to these patients then it is appropriate to test the effectiveness of such episodes. Ten subjects drawn from the University student population were instrumented to measure ventilation, heart rate and end-tidal PCO2 and PO2 breath-by-breath while seated in a comfortable reclining chair. After an initial resting period breathing room air they experienced fifteen, 30-s episodes breathing 6% O2 and 5% CO2 separated by 90 s of breathing air.

Human ventilatory responsiveness to hypoxia is unrelated to maximal aerobic capacity.

Ventilatory responsiveness to hypoxia (HVR) has been reported to be different between highly trained endurance athletes and healthy sedentary controls. However, a linkage between aerobic capacity and HVR has not been a universal finding. The purpose of this study was to examine the relationship between HVR and maximal oxygen consumption (VO2 max) in healthy men with a wide range of aerobic capacities.

Carvedilol improves myocardial contractility compared with metoprolol in patients with chronic hibernating myocardium after revascularization.

Background: We tested the hypothesis of whether carvedilol delays morphologic degeneration and improves functional outcome compared with metoprolol tartrate in patients with hibernating myocardium undergoing surgical revascularization. We have previously shown that patients with chronic hibernating myocardium undergo progressive cellular degeneration and fibrosis.

Methods: Twenty patients with multivessel coronary artery disease revascularization and hibernating myocardium as assessed by technetium-99m perfusion scintigraphy and fluorine-18-fluorodeoxyglucose positron emission tomography were randomized to receive either carvedilol or metoprolol tartrate for at least 2 months before surgery, and this was continued for 7 months postoperatively.

Acute hypoxic ventilatory response and exercise-induced arterial hypoxemia in men and women.

Recent studies claim a higher prevalence of exercise-induced arterial hypoxemia (EIAH) in women relative to men and that diminished peripheral chemosensitivity is related to the degree of arterial desaturation during exercise in male endurance athletes. The purpose of this study was to determine the relationship between the acute ventilatory response to hypoxia (AHVR) and EIAH and the potential influence of gender in trained endurance cyclists and untrained individuals. Healthy untrained males (n = 9) and females (n = 9) and trained male (n = 11) and female (n = 10) cyclists performed an isocapnic AHVR test followed by an incremental cycle test to exhaustion.