How Obesity Fuels Inactivity

 

Women jogging in Central Park New York

Credit: iStock

More than one in three adults and one in six children in the U.S. are obese. Obesity—defined as a serious degree of overweight—is a leading cause of death, disease and disability. Although obesity has been linked to genetic disorders, it is most often caused by unhealthy behaviors and, therefore, is preventable and reversible.

Throughout the day, we get calories from food and we burn the calories off when we move our bodies. When we eat more calories than we burn, our bodies store the excess calories as fat, which accumulates over time. Eating too many calories and not moving enough are two factors that can cause obesity. Only one in five adults in the U.S. meets minimum physical activity recommendations, making physical inactivity a significant contributor to obesity. People who are overweight need to eat fewer calories and/or increase physical activity to lose excess fat. These lifestyle changes are often challenging, and may be compounded by the fact that exercise may be harder to do when you’re obese.

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 The cycle of obesity. Credit: Kim Henige

Carrying excess body weight can make joint pain more likely, which makes physical activity more difficult. Now, researchers may have discovered another reason excess body weight makes physical activity more difficult. A recent study published in the Journal of Applied Physiology shows that the working muscles of obese mice tired out more quickly than those of lean mice. These findings support a cycle of obesity where inactivity leads to obesity, which leads to more inactivity. Breaking the negative cycle of obesity and re-establishing a healthy body weight is possible, but takes considerable dedication and persistence to overcome the barriers and discomfort of the process.

Remember that the path to a healthier weight starts by taking a step! Visit the Centers for Disease Control and Prevention website for weight loss strategies, success stories of people who’ve lost weight and kept it off and more.

Kim HenigeKim Henige, EdD, CSCS, ACSM EP-C, is an associate professor and undergraduate program coordinator in the department of kinesiology at California State University, Northridge.

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-vasauskasAudrey A. Vasauskas, PhD, is an assistant professor of physiology at the Alabama College of Osteopathic Medicine.

When You Can’t ‘Spy’ with Your Eye Anymore

Senior Male With Macular Degeneration

Credit: iStock

Many of us take our ability to read this blog or see the faces of our families and friends for granted. For the 10–15 million Americans with a disease called age-related macular degeneration (AMD), however, the loss of this ability is a daily and devastating reality. AMD is the most common cause of blindness in people over the age of 60.

There are many causes of visual impairment, including near-sightedness, far-sightedness, infection and diabetes. Some of these can be relatively easily corrected with eyeglasses and other medical tools and procedures. AMD currently has no cure, and we are just beginning to understand its causes.

AMD is a gradual and progressive deterioration of the retina, the light-sensing tissue at the back of the eye. The disease affects the most sensitive portion of the retina called the macula. We use the macula to distinguish fine features and colors, and when we lose this function, it can be devastating. AMD slowly causes the photoreceptors—cells that make up the retina—to die, creating blank spots in the field of vision. This occurs when undigested deposits of molecular debris called drusen accumulate in an area that eventually starves the cells that support the photoreceptors.

Genetics is the main factor that makes you more likely to get AMD. Other causes may include smoking and an unbalanced diet. Avoiding smoking and making healthy dietary choices are good ways to reduce your risk of AMD. A recent study published in the journal Cell Stem Cell found that a substance related to vitamin B3 reduced molecular debris and inflammation related to AMD in patients with the disorder. Fish, meat, peanuts and green vegetables all contain vitamin B3.

As the U.S. population grows older, diseases such as AMD are likely to become more prevalent and have a higher social and economic burden than they did in the past. Researchers are actively working to better understand the causes of the disease and how to treat and prevent it.

February is Age-Related Macular Degeneration and Low Vision Awareness Month. If you haven’t had your eyes checked yet this year, now is a good time to make that appointment.

 

grant-kolarGrant Kolar, MD, PhD, is an assistant research professor of pathology and ophthalmology at Saint Louis University School of Medicine.

It’s a Bird, It’s a Plane, It’s Your Thyroid Gland!

 

Thyroid level conceptual meter

Credit: iStock

The thyroid gland—a small, butterfly-shaped gland found at the base of the neck—is the “Clark Kent” of endocrine organs. The thyroid’s actions are extremely powerful, but most people don’t know about its secret superpowers.

An endocrine organ releases substances called hormones into the bloodstream. These hormones are carried to other areas of the body where they have certain jobs to do. The thyroid gland makes hormones that affect many body parts, including bone, muscle, fat, skin, kidneys, and the brain (just to name a few). These hormones are also important for maintaining normal growth and proper metabolism—your body’s ability to convert food into energy.

If your thyroid gland is healthy, it usually means you’re at a healthy body weight and normal body mass index and have normal cholesterol.

People who have low thyroid hormone levels are often very tired, may be overweight and tend to feel cold. Those with higher-than-normal thyroid hormones can show signs of nervousness and heat intolerance and have significant and unintended weight loss.

The nutrient iodine is necessary for the thyroid gland to make thyroid hormones. This is why we have iodized salt: to provide enough iodine in our diet so that our thyroid works well.

January is Thyroid Awareness Month. Learn more about the signs and symptoms of an overactive or underactive thyroid from the American College of Endocrinology. Let’s keep our super thyroid gland super healthy!

audrey-vasauskasAudrey A. Vasauskas, PhD, is an assistant professor of physiology at the Alabama College of Osteopathic Medicine.

How Your Brain Decides to Keep Your New Year’s Resolutions (or Not)

 

New Year goals or resolutions

Credit: iStock

ispy-physiology-100th-post-imageThe start of a new year can feel like a fresh slate or an unwritten book. It’s a chance for many of us to resolve to do things better (eating, exercising) or to stop doing certain things altogether (smoking). But most people don’t succeed in sticking to their resolutions in the long term, and the reason might surprise you. It’s not always a question of lacking willpower or being lazy. Keeping resolutions makes your brain work hard, and that mental effort takes time and practice.

Researchers from the University of Minnesota found that your brain uses more than one decision-making system to build and regulate habit-forming and goal-directed behaviors. One system looks at the steps you take to make a decision. Another evaluates your actions and decides when you need to change a new behavior in order to receive a reward.

Here’s where the hard work comes in: The researchers explain that goal-directed behavior requires mental energy and planning. You have to plan ahead before making decisions to know how to reach your goal. Let’s say, for example, you’re trying to cut back on sweets and are invited to a party. If you want to enjoy a dessert at the party but don’t want to completely ignore your resolution, you’ll need to plan to eat less sugar during the rest of the day. Over time, as you keep making more goal-oriented decisions, the choices become more automatic.

Another study suggests that nerve cells stick together when you form a habit that you’ve enjoyed (such as eating dessert after dinner). The strong bond they create can be tough to break, and—like getting up early to go running or sticking to that diet—it isn’t always easy. This is especially the case when your emotions take over and you feel resentful or angry at the challenging changes you’re trying to make. Being mindful and keeping your emotions out of the decision-making process can help. Your brain, like your body, just needs time to adjust to your new routines.

Good luck and happy new year.

Erica Roth

2016’s Ten Most Read Posts

It’s been a physiology-full 2016 on the I Spy Physiology blog! From exercise to respiration to heart health and beyond, we’ve explored how the bodies of humans and other animals work, adapt and react. Today, we take a look back at our 10 most read posts of the year.

Concussions among football players was headline news in 2016. Against this backdrop, our most popular post of the year looked at how woodpeckers can bang their heads roughly 12,000 times a day at a greater force than the average football hit without sustaining a head injury. Posts about the amazing endurance of Iditarod sled dogs and a researcher’s excellent explanation of what physiology is and why it’s important round out the top three. Check out this year’s top 10:

If you’ve got a topic that you’d like us to cover in 2017, we’d love to hear from you! Share your thoughts in the comments or send us an email.

Stacy Brooks

Handling the Pain of Acid Reflux at Holiday Time

Acid reflux

Credit: iStock

With Thanksgiving coming up, eating—of all things rich, indulgent and delicious—is top of mind for many Americans. But for people with gastroesophageal reflux disease (GERD), eating this type of food often and in large quantities can be a challenge. This week is GERD Awareness Week, a good time to learn how to prevent GERD symptoms and still enjoy your holiday season.

GERD is the return of stomach contents, including acid, into the esophagus, sometimes known as acid reflux. More than 60 million people in the U.S. experience GERD symptoms, such as frequent heartburn, at least once a month.

You may have a higher risk of having GERD if you:

  • produce a lot of gastric acid
  • have a hiatal hernia
  • have a weak lower esophageal sphincter (the ring of muscle between the esophagus and stomach)
  • are obese
  • smoke
  • drink alcohol or a lot of caffeine

Women have additional risk factors, including being a young adult and adopting a stooping or slouching posture. Certain foods, including peppermint, chocolate, fatty or fried foods, and acidic fruits, also raise the risk of developing heartburn and acid reflux.

Simple dietary and lifestyle changes can be effective for many people to reduce the frequency and intensity of GERD symptoms, including:

  • losing weight if needed
  • quitting smoking
  • eating small meals throughout the day
  • avoiding foods that cause symptoms
  • waiting at least two hours before lying down after a meal

Another first line of treatment is medication, such as antacids or proton pump inhibitors. These drugs are available over the counter and by prescription from your doctor and reduce or stop the production of stomach acid to prevent symptoms.

If occasional heartburn bothers you after a big meal, try making lifestyle changes to help you feel better. If your symptoms persist, your doctor may look deeper into the possible causes for your discomfort. Knowing the risk factors for GERD can help you avoid complications and stay healthy throughout the holidays and all year long.

To learn more about GERD, visit the National Institute of Diabetes and Digestive and Kidney Diseases website

 

layla-al-nakkashLayla Al-Nakkash, PhD, is a professor in the Department of Physiology, at Midwestern University, Glendale, Ariz. She is the course director for medical physiology for medical and podiatry students. Her area of research relates to understanding how intestinal dysfunction (in diseases such as cystic fibrosis and diabetes) can be ameliorated by changes in diet.

The Young Qualities of Old Muscle

Senior Adults Taking Spin Class

Credit: iStock

Decline, decrease, deteriorate—all words associated with the aging process. Preventing “D” words is important to keep older people healthy. The loss of muscle is one of the most obvious age-related decreases we experience. Bulky muscles on a person that lifts a lot of weights or the sleek tone of a person that runs a lot of miles shows you that muscles of young people are amazing in their ability to change with the demands put on them. Scientists call this ability to change “plasticity.” When and why does muscle plasticity decline?

As individuals age, large muscle fibers that allow explosive types of movements, such as jumping or lifting a heavy weight, disappear more than small muscle fibers that allow slow, low-force movements such as grabbing a cup or adjusting posture. A recent Journal of Applied Physiology podcast discusses a research article that looked at small, medium and large muscle fibers from a group of subjects who were ages 87 to 90. At this age a substantial decline in strength is expected. However, the study showed that even though large muscle fibers are lost in old age, medium-sized muscle fibers become very strong for their size to compensate for that loss. The amount of force the medium-sized fibers could generate for their size was greater than muscle fibers from a group of young subjects and was similar to a world-class sprinting athlete. Therefore, the medium-sized fibers in the muscle of a very old group of subjects were plastic and adapted to the loss of bigger more explosive muscle fibers.

Future research is needed to determine if this plasticity is apparent in all old individuals or whether it was unique to this group that was still fairly active. Also, it is still unknown why some types of fibers keep this plasticity and others do not. Although older muscle does decline, decrease and deteriorate, plasticity appears to remain, which provides an interesting avenue to prevent the “D” words.

Ben MillerBenjamin Miller, PhD, is an associate professor in the department of Health and Exercise Science at Colorado State University. He co-directs the Translational Research in Aging and Chronic Disease (TRACD) Laboratory with Karyn Hamilton, PhD.

Physiology for the Armchair Scientist

 

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Visit PhysiologyInfo.org

Want to learn more about physiology without going back to school for a PhD? Check out www.physiologyinfo.org. The website, hosted by the American Physiological Society, goes in-depth to explain the multi-faceted field of physiology to nonscientists. In addition to examining hot and emerging areas of research such as brain physiology, obesity and exercise, we look at the how the body’s systems work individually and together to keep us going every day.

Our reference library houses quizzes that will test your physiology smarts, dozens of podcasts on cool research findings, a library of vintage equipment dating as far back as the 1870s and much more. We also feature timelines that highlight important milestones and people in the history of physiology.

We hope the site will serve as a helpful and informative resource about our area of research. Check back often for new information. And if you have questions you’d like us to address, let us know!

Stacy Brooks