Healthy people have healthy responses to snow shoveling

November 13, 2001

ANAHEIM, Calif., Nov. 13 - Although manual snow shoveling is a common trigger of heart attack, it doesn't negatively affect blood clotting in healthy males, according to a study presented today at the American Heart Association's Scientific Sessions 2001 conference.

The findings suggest that different types of physical activity have varying effects on blood coagulation or clotting, with moderate exercise protecting young, healthy men.

Since the early 1990s, several studies have suggested that manual snow shoveling increases heart stress and, potentially, the risk of heart attack, especially in individuals who have heart disease or risk factors. These studies are bolstered by evidence of a rise in the heart attack rate after a heavy snowfall.

Many of the studies evaluating snow shoveling and heart attack risk have focused on changes in blood pressure and heart rate, and observed dramatic increases in both. This study focused on factors that affect the blood's ability to clot.

"We know that the majority of heart attacks, including those that occur after physical exertion, result from the formation of a thrombus or clot,"[ says Christopher J. Womack, Ph.D., assistant professor of exercise physiology at Michigan State University in East Lansing. "The clot forms the final blockage in the coronary artery, leading to the heart attack."

The study involved 11 healthy young men (average age 26 years) who performed three types of physical activity: a standard maximal treadmill exercise test, 10 minutes of shoveling snow at their own pace, and 10 minutes of removing snow with a snow blower. Each activity was performed on a separate morning. Blood was drawn before and after each activity and analyzed for changes in the activity of tissue plasminogen activator (tPA, a clot-dissolving enzyme) and plasminogen activator inhibitor 1 (PAI-1, which inhibits clot dissolving) and in levels of tPA antigen (a marker of inactivated tPA and increased clotting potential).

Treadmill exercise increased tPA activity by 33 percent and decreased PAI-1 activity by 34 percent, while tPA antigen levels rose by an average of 274 percent. Following manual snow shoveling, PAI-1 activity decreased by an average of 14 percent, tPA activity remained at normal pre-exercise levels, and tPA antigen levels increased by 63 percent. Use of the snow blower was not associated with changes in any of the clotting factors.

"Different forms of exercise will cause different physiologic responses, especially some of those associated with increased clot dissolving," says Womack. "That finding surprised us because levels of lactic acid, which is a marker of physical strain and exercise tolerance, were higher during manual snow shoveling than during automated snow removal. The heart rate response also was higher during snow shoveling than automated snow removal. "Given the increase in blood lactate, we would have expected to see an increase in the potential for coagulation. The findings could suggest that different factors control blood clotting versus clot dissolving, but we don't know that for sure," says Womack.

The findings may support the idea that young, healthy individuals have protective responses to moderate exercise that prevent heart attacks. In addition, for these young healthy individuals, snow shoveling did not appear to be as physically stressful as maximal treadmill exercise, but was significantly more stressful than automated snow removal.

Whether the findings apply to older individuals, who are at greater risk for heart attack, remains to be determined in a follow-up study the investigators are conducting.

"There is already good data to show that aging reduces the potential for clot dissolving," Womack says. "We want to find out whether aging also affects the response of these parameters during exercise."
Other investigators in the study are: Chad Michael Paton, B.S.; Adam M. Coughlin, B.S.; Adam T. Dejong, M.S.; Jamie Anderson, B.S.; and Barry A. Franklin, Ph.D.

NR01-1352 (SS2001/Womack)

For information Nov. 10 - 14, call:
Karen Hunter or Bridgette McNeill
at the Hilton Anaheim Hotel
(714) 251-5801

Abstract 2882

American Heart Association

Related Heart Attack Articles from Brightsurf:

Top Science Tip Sheet on heart failure, heart muscle cells, heart attack and atrial fibrillation results
Newly discovered pathway may have potential for treating heart failure - New research model helps predict heart muscle cells' impact on heart function after injury - New mass spectrometry approach generates libraries of glycans in human heart tissue - Understanding heart damage after heart attack and treatment may provide clues for prevention - Understanding atrial fibrillation's effects on heart cells may help find treatments - New research may lead to therapy for heart failure caused by ICI cancer medication

Molecular imaging identifies link between heart and kidney inflammation after heart attack
Whole body positron emission tomography (PET) has, for the first time, illustrated the existence of inter-organ communication between the heart and kidneys via the immune system following acute myocardial infarction.

Muscle protein abundant in the heart plays key role in blood clotting during heart attack
A prevalent heart protein known as cardiac myosin, which is released into the body when a person suffers a heart attack, can cause blood to thicken or clot--worsening damage to heart tissue, a new study shows.

New target identified for repairing the heart after heart attack
An immune cell is shown for the first time to be involved in creating the scar that repairs the heart after damage.

Heart cells respond to heart attack and increase the chance of survival
The heart of humans and mice does not completely recover after a heart attack.

A simple method to improve heart-attack repair using stem cell-derived heart muscle cells
The heart cannot regenerate muscle after a heart attack, and this can lead to lethal heart failure.

Mount Sinai discovers placental stem cells that can regenerate heart after heart attack
Study identifies new stem cell type that can significantly improve cardiac function.

Fixing a broken heart: Exploring new ways to heal damage after a heart attack
The days immediately following a heart attack are critical for survivors' longevity and long-term healing of tissue.

Heart patch could limit muscle damage in heart attack aftermath
Guided by computer simulations, an international team of researchers has developed an adhesive patch that can provide support for damaged heart tissue, potentially reducing the stretching of heart muscle that's common after a heart attack.

How the heart sends an SOS signal to bone marrow cells after a heart attack
Exosomes are key to the SOS signal that the heart muscle sends out after a heart attack.

Read More: Heart Attack News and Heart Attack Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to