Spinal Cord Injury: Let’s Clear the Air(ways)

Human Spine Anatomy

Credit: iStock

The spinal cord is the information processing highway in animals (including humans) that have a backbone. In humans, the spinal cord contains nerve cells called motor neurons that control movement in the muscle fibers of the body, similar to the way a puppeteer controls the movements of a puppet.

About 17,000 people in the U.S. sustain new spinal cord injuries (SCI) each year, and roughly 300,000 people in the U.S. live with an SCI. Motor neuron damage in the spinal cord may lead to a variety of problems, including:

  • decreased mobility and independence;
  • loss of independent breathing;
  • injuries associated with using a wheelchair, such as pinched nerves and muscle strain;
  • partial or total inability to control the bowels and/or bladder; and
  • sexual dysfunction.

New research is addressing all of these important problems, but one area that is not as widely studied is airway clearance. Most of the time we can clear our airways ourselves through coughing and sneezing, but these actions become more difficult with SCI. Close to half of all people with SCI have damaged the motor neurons that control their diaphragm, the muscle that sits below the lungs and helps us breathe. As a result, people with SCI have an increased risk of potentially fatal airway infections such as pneumonia.

Fortunately, about 90 percent of these injuries are incomplete, meaning that some of the neurons still function. People with incomplete SCI have some sensation below the injury site and can often breathe on their own. We only need 10 to 20 percent of our diaphragm muscle to activate in order to breathe, but almost the entire muscle needs to be functional to cough and sneeze. When the motor neurons controlling the diaphragm are injured, the organ isn’t able to generate the forces necessary to clear the airways fully.

Over time, the neurons in the diaphragm that still function in an incomplete SCI may adapt to take over other jobs besides just breathing. This is called neuroplasticity. Neuroplasticity in the spinal cord is a valuable topic of research.  Researchers are looking for new ways to manipulate this process to help people with SCI learn new airway clearing methods which would likely reduce their health risks and improve their quality of life.

 

obaid-khurram-15978141Obaid Khurram is a PhD candidate in the biomedical engineering and physiology program at Mayo Clinic Graduate School of Biomedical Sciences. His research focuses on the neuromotor control of the diaphragm muscle, particularly after motor neuron loss or muscle weakness.

 

What Animals Can Teach Humans about Muscle Maintenance

Hiding Groundhog

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We all know the saying “use it or lose it.” Your muscles and nerves are no exception. When people are not active, whether it’s because of bed rest, spinal cord and nerve injury, or other reasons, two big problems arise. First, the muscles shrink by losing protein (a state called atrophy). Second, nerve cells have trouble firing electrical signals to communicate with the muscles. This combination can make it harder for people who are inactive to perform normal activities in their daily lives.

Unlike in humans, inactivity in other animals is not always such a bad thing. Certain animals in the wild need to stay inactive (dormant) to survive in their environment. During times of low food availability and harsh environmental conditions, ground squirrels, frogs, bats, turtles and bears may remain inactive. In the winter, this is called hibernation, and in the summer, it’s known as estivation. Quite often, these animals’ muscles are less active than normal or completely inactive for several months at a time. Some frogs can even survive under water during the winter without using their breathing muscles. Based on the idea of  “use it or lose it,” you might think that hibernating animals wouldn’t be able to run, jump, fly or even breathe normally after months of not using their muscles. Think again!

Understanding how animals immediately return to using their muscles and nerves normally after long stretches of dormancy is a major area of research. By learning how different animals dodge neuromuscular problems related to inactivity, scientists can figure out why human muscles and nerves are not as well-equipped. For example, hibernating animals activate genes that reduce the loss of muscle protein and use less energy during periods of inactivity to avoid atrophy. These discoveries have the potential to provide new treatment options for people who are confined to bed rest or who suffer nerve injuries that leave muscles unable to contract.

Animals have already solved many problems that plague humans, such as nerve and muscle inactivity. Research that compares animal and human function is an example of comparative physiology. Comparative physiology findings can help scientists make important discoveries that would not be possible if the cures hiding inside animals were overlooked.

Joe SantinJoe Santin, PhD, is a postdoctoral fellow at the University of Missouri-Columbia.

 

Can Exercising in Low-Oxygen Conditions Help Breast Cancer Survivors?

Supporting each other in the race against breast cancer

Credit: iStock

Physical activity has been linked to a lower risk of developing several types of cancer, including breast cancer. Walking a few hours a week may even decrease the risk of a breast cancer recurrence as well as dying from the disease. The American Cancer Society currently recommends that people recovering from cancer should exercise at least 150 minutes per week.

But people with breast cancer often face a number of challenges to establishing a regular exercise program. Chemotherapy and radiation can affect heart and lung function, and about 60 percent of breast cancer survivors have reduced strength in their legs as a result of a loss of muscle mass. In addition, more than 80 percent of women gain weight after a diagnosis of breast cancer. These factors, along with fatigue from treatment, can prevent breast cancer survivors from being as active as they want to be.

Knowing that exercise is beneficial for people with breast cancer but that they face challenges, researchers at the University of Alabama at Birmingham (UAB) are looking at new ways to improve breast cancer survivors’ response to exercise. Their study compares the effects of exercising under low-oxygen conditions—similar to that seen at an altitude of 7,000 feet—with exercising in normal oxygen conditions at sea level.

Elite athletes sometimes train in mountainous areas—between 5,000 and 8,000 feet above sea level—to improve their performance. The air at high altitudes is thinner and contains less oxygen. Lower oxygen levels help boost the number of red blood cells that carry oxygen around your body. Exercising at high altitudes also lets you train harder without the added stress on your joints and muscles that occur at sea level.

While it is impractical to take cancer survivors to the mountains, UAB researchers are trying to bring the mountains to the patients During exercise sessions, participants wear a mask that is connected to a machine that controls the amount of oxygen they breathe in. This mimics the low-oxygen levels of a high-altitude workout.

The study is ongoing, so it is too soon to know how beneficial exercising under lower oxygen levels will be. However, the researchers predict that exercising in low-oxygen conditions will trigger a number of physiological changes that will let people with breast cancer be more active and improve their overall health. If the results of the study are correct, it may lead to new approaches to help breast cancer survivors lead a more active life.

 
John Chatham

John Chatham, DPhil, is a professor of pathology and director of the Division of Molecular and Cellular Pathology at the University of Alabama at Birmingham.

Not Horsing Around: Therapeutic Effects of Horseback Riding

Anne with students and Paralympians

Anne R. Crecelius, PhD, and students visit with La Roja Paralimpica athletes in Chile.

Choosing your favorite part of a trip can be a difficult decision for travelers. I had countless unforgettable and unique experiences during a recent four-week trip to Chile. One excursion that stands above the rest was a weekend trip to San Pedro de Atacama in Northern Chile.

I was studying with a group of students who had booked a horseback riding tour through the oasis of Sequitor. With the Andes Mountains as our backdrop, we spent two hours enjoying the perfect blue sky, warm sun and crisp air. This small agricultural region is in what is often called the driest desert in the world.

I had never been horseback riding and did not realize how much coordination, strength

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Molly Gearin tries her hand at horseback riding.

and physical and mental stamina it required. I later learned that horseback riding is a type of rehabilitative treatment—called hippotherapy—that may improve coordination, balance and strength in people with physical disabilities, including cerebral palsy (CP).

CP is a neurological disorder that affects body movement and coordination. Studies have shown that hippotherapy can improve joint stability, balance and painful muscle contractions in people with CP. Children with CP may especially benefit from hippotherapy. Therapeutic riding can change how the abdominal and lower back (core) muscles respond to different movements. These physiological benefits can improve posture and the overall quality of life in some children, particularly among those who have the ability to walk, run and jump.

Researching hippotherapy was not the first time I thought about people with CP on our trip to Chile. Another favorite activity was our opportunity to watch La Roja Paralimpica, the Chilean Paralympic Fútbol 7-a-side team, practice. This sport is adapted from traditional fútbol (soccer) to accommodate athletes with disabilities. The modified rules allow Paralympic athletes to enjoy a sport that is at the heart of Chilean culture.

As a future physical therapist, I enjoyed observing elite athletes at work and learning about hippotherapy, an activity that could be of benefit to people with CP.

– Molly Gearin (Anne Crecelius contributed to this post)

Molly Gearin is a pre-physical therapy major at the University of Dayton. Anne R. Crecelius, PhD, is an assistant professor in the Health and Sport Science Department at the University of Dayton. They spent four weeks in Chile as part of a study abroad program in partnership with the Universidad de los Andes studying nutrition, sports and research in the context of the Chilean culture. This is the first in a three-part series that spies physiology in this dynamic South American country.