Putting Out Fires Hurts Firefighters’ Hearts

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As the temperature outside rises, our bodies make adjustments to keep our internal temperature constant to prevent us from overheating through a process called thermoregulation. This includes bodily functions such as sweating and widening of the blood vessels (vasodilation). When we sweat, perspiration evaporates from our skin to cool us down. When the blood vessels under our skin widen, our heart pumps more blood to our skin, which releases more heat from our inner body.

Our bodies are constantly working to hold a steady core temperature around 98-100 degrees Fahrenheit (F). This allows our organs to function properly. But when the temperature outside is extremely hot, our temperature can start to rise. A person with a body temperature above 104 degrees can develop heat stroke. This can cause dizziness, difficulty breathing, confusion, seizures or loss of consciousness. Brain and heart damage—sometimes permanent—can occur when body temperature climbs above 107 degrees F.

Too much summer heat can be unhealthy for everyone, but it can be especially dangerous to firefighters. The incidence of fires increases in the U. S. during the summer months. Firefighters fight almost twice as many fires in the summer compared to the rest of the year. On top of dealing with the extreme heat (sometimes over 700 degrees F!), these first responders face extreme physical exertion, mental stress and smoke inhalation on the job. All of these factors together can place firefighters in immediate danger of heat exhaustion, heatstroke and heart problems. In fact, firefighters are up to 136 times more likely to die from coronary artery or heart disease during or soon after they suppress a fire.

In a study published in Circulation last month, researchers may have uncovered several reasons why putting out fires puts firefighters at risk for heart disease. They discovered that a single, 20-minute session of fire simulation training—where healthy firefighters were exposed to physical activity in the extreme heat (about 755 degrees F)—was enough to injure their blood vessels, even though the firefighters’ core body temperature never reached above 101 degrees F. The problem: Although the firefighters’ bodies did keep their core temperature within a healthy range, their blood vessels did not relax properly immediately after the training. Also, as a result of the training, the firefighters’ blood clotted more easily. Damaged blood vessels and increased clotting of the blood can be very harmful to the heart and sometimes can lead to a heart attack.

This research shows us that even when we are able to keep our body temperature from getting too high, there are hidden dangers of being physically active in extremely hot temperatures. So keep your heart healthy this summer and don’t overexert yourself while outdoors!

Dao Ho, PhD

Dao H. Ho, PhD, is a biomedical research physiologist at Tripler Army Medical Center. The views expressed in this blog post are those of the author and do not reflect the official policy or position of the U.S. Department of the Army, U.S. Department of Defense or the U.S. government.

Walking and the Brain, Aromatherapy for Horses and a Whole Lot More!

Physiology, the study of function from microscopic cells to complete organ systems, encompasses a wide range of fascinating topics. The annual Experimental Biology (EB) meeting is a showcase for thousands of researchers studying humans and animals alike. Check out some of the research presented at last month’s meeting in Chicago:

Close up shot of runner's shoes

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Most people know that walking is good for heart health, weight management and flexibility. New research from New Mexico Highlands University reveals how your brain also benefits from walking. Each step you take sends pressure waves through your arteries and increases blood flow—and oxygen—to the brain. The researchers found that running also had a beneficial effect on blood flow, while sports like cycling that don’t involve foot impact were less likely to make a significant difference.

Dressage test

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Do you like the calming scent of lavender when the pressure’s turned up? Turns out, you’re not alone. Research out of Albion College studied the effects of aromatherapy on horses. Much like people, competition horses get stressed out when they’re transported from their home to an unfamiliar venue. Stress reduction therapies are highly regulated in competition horses, and non-medicinal treatments could go a long way to calm the animals before they perform. The researcher found that stress hormone levels dropped significantly among trailered horses that were exposed to lavender aromatherapy when compared to distilled water mist.

Two women rowing on a lake

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Olympic-caliber athletes appear to be the picture of strength and power. But new research suggests that high-intensity workouts without a proper recovery period could interfere with optimum bone health. A study of female Olympic rowers from Canada’s Brock University showed that the levels of a protein that stops bone mineral loss dropped during extended periods of heavy training. Bone mineral loss weakens the bones and increases the risk of stress fractures and osteoporosis.

These studies just scratched the surface of all the top-notch physiology research presented at EB. Read more highlights from this year’s meeting:

Why vitamin A and a high-fat diet don’t mix

The role of immune cells in the cause—and treatment of—preeclampsia

How an ice bag on the face can help treat severe blood loss

An “exercise pill” may be in our future

How orange essential oil reduces PTSD symptoms

 

Erica Roth

Go Ahead, Wear Your Heart on Your Sleeve!

Jousting Competition

A jousting knight wears his heart on his sleeve. Credit: iStock

In medieval times, a jousting knight would wear the colors of the lady he was courting tied around his arm. Hence, the phrase “Wear your heart on your sleeve” was born. Today, we use this romantic phrase to describe someone who expresses their emotions openly. How applicable that ancient phrase really is to maintaining a healthy heart!

In a landmark paper, a group of scientists discussed how stress and social interactions with others affected the health of the heart. It is well-known that stress is a major factor in the development of heart disease. This is because stress is a double whammy: It activates the “fight-or-flight” nervous response, and it causes inflammation in the cells that line blood vessels. Both of these events can damage blood vessels in the heart.

Research shows that positive social interaction expressing emotion is important for heart health. Support from a spouse or partner, friends or other groups can reduce stress and help you stick to a healthy diet and exercise program to minimize your risks.

Heart disease is the leading cause of death worldwide, with annual deaths creeping up to 24 million. Reducing stress and anxiety is an important aspect of keeping your heart healthy. Exercise, yoga, meditation and even deep breathing can promote a sense of calm when tensions mount. Try running or yoga with a friend or join an exercise class to keep you on track for a healthy heart. Go ahead, wear your heart on your sleeve—it’s good for you!

February is American Heart Month. You can find more information about keeping your ticker ticking on the American Heart Association’s website.

Audrey Vasauskas

Are You at Risk for Type 2 Diabetes?

Diabetes text with felt tip pen (Click for more)

During American Diabetes Month in November, you may notice more people are talking about diabetes, a disease that affects 29 million Americans. It’s a great time to learn more about diabetes and the ways that you can decrease or manage your risk of developing the disease.

Diabetes mellitus is a problem with how your body handles blood glucose (sugar). People who have type 2 diabetes aren’t able to use the hormone insulin properly to remove glucose from the bloodstream for use in the fat and muscle cells.  Ultimately, this causes people with type 2 diabetes to have higher than normal levels of glucose in their blood.

You may have heard that someone who is overweight and has a large, apple-shaped body is more likely to develop metabolic syndrome—a group of health conditions such as elevated blood pressure, blood sugar and cholesterol levels—which may increase the risk of developing diabetes.  However, there are a number of less well known risk factors for type 2 diabetes including:

Some research even links non-health-related factors such as job security to an increased diabetes risk. A recent study published in the Canadian Medical Association Journal  analyzed data from 19 different studies including almost 141,000 participants which suggested that job insecurity was associated with a modest increased risk of diabetes.  Job insecurity has also been associated with weight gain (a diabetes risk factor) and coronary artery disease (a complication of diabetes).

Recognizing risk factors for diabetes and dealing with them, if possible, is important for both children and adults. Consuming a healthy, nutrient-rich diet and staying physically active can help maintain weight, manage stress and avoid type 2 diabetes and its many related complications. To learn more about ways to prevent diabetes, visit the American Diabetes Association website.

barb-goodman

Barb Goodman, PhD, is a professor of physiology at the University of South Dakota.

The Physiology of a Good Scare

Young scared couple is watching horror on TV.

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With Halloween next week, you may be planning to head to a haunted house or cozy up on the couch with popcorn and a horror flick. Either way, you’re probably hoping for a good scare.

Enjoying the thrill of a scary movie or riding a rollercoaster isn’t the same as a real life-threatening situation, but your body doesn’t always know the difference. This is because the same senses are triggered when you’re startled in a safe environment as when there’s a genuinely fearful situation. Whether the fear is real or fake, your body leaps into action to prepare for whatever is going to unfold:

  • Your cardiovascular system pumps more blood and your heart beats faster.
  • Your brain sends adrenaline to your skeletal muscles, getting ready to move.
  • Your pupils dilate so you can see better.
  • Your digestive system slows down until the threat has passed.

Referred to as the “fight or flight” response, the human body functions similarly to how it would have thousands of years ago when faced literally with these two options: fight (for food or for your life, for example) or flight (run away).

During the physiological reaction to fear, scientists believe the brain stimulates the production of dopamine, a chemical that activates the pleasure center of the brain. Many people enjoy the feeling of a good scare and pursue other thrill-seeking behaviors to get the same “high.” Research suggests that thrill-seekers may have different brain chemistry than those who don’t enjoy a heart-pounding experience. If you don’t like to be scared, skip the tricks, enjoy the treats and remember to breathe deeply during this spooky season.

No matter where you fall on the scare scale, be safe this Halloween!

Erica Roth