"This study can help us understand why cold air is such a trigger for coronary events," said Lawrence I. Sinoway, Distinguished Professor of Medicine and director of the Heart and Vascular Institute, Penn State College of Medicine.
Breathing cold air during exercise can cause uneven oxygen distribution throughout the heart. But a healthy body generally corrects for this problem and redistributes blood flow, making sure the heart continues to function properly. In people with heart problems -- such as coronary artery disease -- this may not be the case, said Sinoway.
"If you are doing some type of isometric work and you're breathing cold air, your heart is doing more work -- it's consuming more oxygen," said Sinoway, also director of the Clinical and Translational Science Institute at Penn State.
Isometric work includes such activities as shoveling snow and carrying a briefcase or laptop bag. The heart works harder when exerted in cold temperatures and the number of deaths due to cardiac arrest peaks during the winter.
"There are two different things going on here -- demand and supply," said Matthew D. Muller, postdoctoral fellow at the Heart and Vascular Institute, Penn State College of Medicine. "We thought that oxygen demand in the heart would be higher with cold-air breathing and we also thought that oxygen supply would be a little bit impaired. And that's generally what we found."
Sinoway, Muller and colleagues reported their results in a recent issue of the Journal of Applied Physiology and in the current issue of the American Journal of Physiology, Heart and Circulatory Physiology.
The researchers first studied healthy young adults in their 20s and then studied a group of healthy older adults in their 60s so that they could learn how the heart functions in people without disease. Each subject was monitored for lung function and heart functions during the trials.
In order to measure heart function during exercise, the participants performed an isometric, or static, handgrip, which is a maneuver known to increase blood pressure. Subjects squeezed the handgrip device and held it still for two minutes, providing a consistent workload on the heart for the researchers to measure. Muller and Sinoway found that there was a supply-demand mismatch in the left ventricle -- where the heart receives oxygenated blood -- yet the heart was able to continue functioning appropriately.
These findings "suggest that healthy humans can adequately redistribute blood to the subendocardium (the blood vessels entering the heart) during the combined stimulus of cold-air inhalation and handgrip exercise," the researchers stated.
Also working on this research were Zhaohui Gao, instructor; Rachel C. Drew, postdoctoral fellow; Michael D. Herr, biomedical engineer; Urs A. Leuenberger, physician and professor of medicine; and Jessica L. Mast and Cheryl A. Blaha, clinical research nurses, all at the Heart and Vascular Institute, Penn State College of Medicine.
The National Institutes of Health and the Wilderness Medical Society both supported this research.
Victoria M. Indivero | EurekAlert!
Biofilm discovery suggests new way to prevent dangerous infections
23.05.2017 | University of Texas at Austin
Another reason to exercise: Burning bone fat -- a key to better bone health
19.05.2017 | University of North Carolina Health Care
Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.
Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....
Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.
The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....
An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...
24.05.2017 | Event News
23.05.2017 | Event News
22.05.2017 | Event News
26.05.2017 | Life Sciences
26.05.2017 | Life Sciences
26.05.2017 | Physics and Astronomy