Strength in Numbers
Millions of Americans suffer pain and weakness from injury, aging, and disuse. Two dozen Ohio University scientists explore the secrets behind our muscles, brain, and nervous system to provide relief.
June 13, 2011
Thomas uses such high-tech tools to understand the physical and neurological mechanisms of our muscles—as well as problems such as back pain—and to explore therapies that might bring sufferers relief.
In a recent study funded by a $1.5 million National Institutes of Health grant, Thomas and colleague Christopher France focused on a phenomenon called “fear avoidance.” In this self-fulfilling prophecy, people who fear reinjuring their backs after a painful accident move in restricted, unnatural ways that eventually can lead to re-injury—and further back pain.
Illustration credit: Tina Ullman.
“We’ve been able to identify the relationship between fear and movement,” says Thomas, an associate professor of physical therapy, explaining how test subjects were divided into groups based on their degree of fear of reinjury. France, a professor of psychology, and Thomas asked the subjects to perform motions such as leaning forward to touch a post or bending over to reach a box, using machines that Thomas custom built in his lab. The motion-capturing cameras recorded their movements. The researchers discovered that people who were extremely afraid of reinjury—even if they no longer had pain from their original injury—showed all the symptoms of fear avoidance.
“They’re still moving differently; they’re still protecting the spine,” Thomas says, noting that people suffering from fear avoidance often end up with less endurance, strength, and range of motion in their backs. “We suspect that this could be driving the reoccurrence of low-back pain,” he explains. In order to help patients fully recover from back injuries, Thomas says, any therapies used to help people who show strong fear avoidance must take their fear into account.
France and Thomas are two of the principal investigators of the Ohio Musculoskeletal & Neurological Institute (OMNI), an Ohio University College of Osteopathic Medicine institute devoted to understanding the causes, treatment, and prevention of musculoskeletal and neurological disorders brought on by such factors as aging, injury, and disuse. The institute brings together more than 20 Ohio University scientists from eight departments in four colleges. Over the past decade, OMNI’s five principal investigators alone have been awarded more than $6 million in federal funding, and published more than 250 peer-reviewed articles. In 2005, the institute received infrastructure funding from the Osteopathic Heritage Foundations.
Brian Clark, director and principal investigator of OMNI. Credit: John Sattler.
“OMNI breaks down departmental barriers. The collaboration has raised the bar on all the work,” says Brian Clark, director and principal investigator of OMNI and an assistant professor of biomedical sciences in the College of Osteopathic Medicine.
“It’s a more complex and 360-degree approach,” agrees Thomas. “We all think about things in a different way. It’s where the sum of the parts is really quite greater than the individual.”
OMNI has its work cut out for it. Musculoskeletal disorders and diseases are the leading cause of disability in the United States, accounting for more than half of all chronic conditions in people older than 50. Each year, these disorders cost the United States more than $850 billion in health care costs and lost wages, or 7.7 percent of the U.S. gross domestic product—five times more than the costs associated with diabetes. Neurological disorders and diseases have similarly bleak numbers: One in nine people worldwide die of a disorder of the nervous system. These burdens are expected to increase as people lead more sedentary lifestyles and as the U.S. population ages.
To get a leg up on these alarming trends, Clark says, during the next five years OMNI intends to focus its resources and endeavors on research programs in the following areas: low back and chronic pain disorders; sarcopenia (age-related loss of muscle mass) and dynapenia (age-related loss of muscle strength); exercise physiology and rehabilitation medicine; the biology of manual therapies; and connective tissue, bone, and cutaneous biology. It’s an important societal issue, he says, to discover the physiological causes of musculoskeletal and neurological disorders. “If we figure out the mechanism,” Clark explains, “then we can develop the correct therapies.”
In their work on low back and chronic pain disorders, OMNI scientists are exploring how and why the low back muscles fatigue. Historically, this type of work has been complicated because of the miniscule size and complexity of the muscles involved. “There’s a reason no one has yet done extensive research on lower back muscles,” Thomas says, explaining that as technology advances, he expects that to change. The muscles of the lower back, he added, work—and fatigue—in a completely different way than the muscles of the arms and legs.
To overcome these issues, OMNI researchers are examining how to improve studies of muscle fatigue in the lower back. “It turns out that one of the great predictors of lower-back pain is essentially a fatigue test,” Clark says, explaining that since 1984, a test called the Sorensen has been used to evaluate muscle fatigue. A subject performing this test lies face down on a table. Then he moves forward until his upper body is unsupported by the table but still horizontal with it. The length of time the subject can hold that position is predictive of whether the subject will develop back pain.
Physical therapist Jim Thomas uses motion-capture technology to learn more about how people who’ve experienced back pain move differently than healthy subjects. Credit: Rick Fatica.
A problem with this test is that scientists are not sure how a person’s body mass affected the results. Thomas recently built a machine to improve on the Sorensen test. It counters the mass of a person’s trunk, removing gravity from the equation. He and other OMNI scientists are using the device in experiments to compare how long it takes subjects’ trunk muscles to fatigue while supporting a load versus pushing back against a restraint.
Clark, Thomas, and fellow OMNI principal investigator David Russ, an assistant professor of physical therapy, also have used a commercially available exercise machine—one in which subjects sit upright—to run the same kind of tests. The researchers found that the test subjects were able to push back at a given level of force with their trunk muscles longer than they could simply hold a position while supporting a load of the same magnitude. This finding should be examined in patients with low back pain, Clark says, as understanding the mechanisms underlying back fatigue following injury could help clinicians prescribe specific rehabilitation exercises.
Some back pain sufferers turn to osteopathic physicians or physical therapists for manipulation treatments to ease their discomfort. According to a national survey, more than 18 million adults received manipulative therapies in 2007. Scientists, however, still don’t fully understand the mechanisms behind these treatments.
Clark, Thomas, and Steven Walkowski, an assistant professor of family medicine in the College of Osteopathic Medicine, recently completed a study, funded by the Osteopathic Heritage Foundations, on the neurophysiologic effects of manipulation on the back muscles. The researchers performed tests on the muscles, brains, and reflexes of both healthy individuals and people who have chronic back pain.
Illustration credit: Tina Ullman.
“There’s very little data out there on dosage,” Thomas says, noting that important questions sometimes are not even asked before a sufferer of chronic back pain begins a manipulation therapy. Those questions include: What type of manipulation should be used? How often should the back be manipulated? And, perhaps the most important question: Should an individual undergo manipulation at all?
The researchers found that if the clinician—not the test subject, but the clinician—manipulating a subject’s back heard a “pop” during the treatment, there was a 20 percent decrease in the subject’s low back muscle stretch reflex excitability. Researchers observed this effect even in the healthy people, Clark says. This finding may indicate that manipulation lessens the “spasm” effect—which sometimes accompanies back pain— and could help better identify which patients may benefit from manipulative treatment.
In addition to studying the mechanics of these therapies, OMNI researchers have worked for the past decade on a new method of training medical students in manipulation skills. Robert Williams, professor of mechanical engineering, and John Howell, associate professor of biomedical sciences in the College of Osteopathic Medicine, have developed a virtual reality program that simulates the experience of palpating and diagnosing musculoskeletal dysfunctions of the spine. This work has been funded by numerous private foundations, including more than $1 million in grant support from the Osteopathic Heritage Foundations. The program has now been formally integrated into the curriculum for first-year Ohio University medical students.
Though solving the nation’s back pain problems is a huge task itself, the OMNI researchers are simultaneously tackling another looming issue in American health care: understanding muscle weakness and fatigue in the growing population of older adults.
For the past 20 years, scientists generally believed that older adults became weaker because they lost muscle mass. However, “loss of mass explains only about 10 percent,” Russ says, pointing out studies that have shown growth of muscle does not lessen fatigue rates or increase strength. In recognizing OMNI’s unique approach to this issue, the NIH recently awarded a $426,000 grant to Clark, Russ, Thomas, and Janet Taylor from the University of New South Wales in Australia. The team will work to identify inhibiting properties and functions of the brain that might be the cause of muscle weakness that comes with aging and with immobilization in a cast.
The researchers will use a procedure called transcranial magnetic stimulation, which Clark uses to pursue his main research focus on determining the possible neurological origins of muscle weakness and fatigue. The procedure features a hat-like device made of superpowered coils that produce a rapidly changing magnetic field; the coils introduce noninvasive electrical current to the brain. In his Neuromuscular Physiology Laboratory, Clark demonstrates how the stimulation of different parts of the brain causes corresponding muscles to contract and explains that—his research uses aside—the procedure can also be used to treat depression and chronic pain.
Illustration credit: Tina Ullman.
OMNI scientists are not only investigating the neurologic mechanisms of muscle weakness, but are looking into the role of skeletal muscle. In his Laboratory for Integrative Muscle Biology, Russ studies the muscle tissue of young and old rats, as well as human muscle biopsies, to investigate the possibility that proteins in older adults’ cells become less effective at releasing calcium. The release of calcium causes muscles to contract. If that release is impaired, muscles become less able to do their job, leading to fatigue and weakness. Russ’ most recent work has confirmed such an impairment in aging rats.
Because many musculoskeletal and neurological conditions respond favorably to exercise, OMNI researchers also are focused on exercise physiology and rehabilitation medicine. Russ, for example, is studying how sprint exercise enhances muscle function and alters the calcium release process in muscle. However, since sprinting may not be beneficial (or even possible) for many older adults, OMNI researchers are investigating other exercise interventions. For example, through a grant awarded by the American College of Sports Medicine, Clark is investigating the effectiveness of blood flow-restricted exercise—a type of low-intensity resistance exercise done while wearing on the thigh a device resembling a blood-pressure cuff. The cuff, which applies modest pressure to the limb, “reduces the amount of blood going to the muscle and restricts some of the blood from going back to the heart,” and “causes the muscle to sit there in its metabolic byproducts, in a manner similar to that which occurs with sprinting,” Clark explains.
Recently, Clark and colleagues found that blood flow-restricted exercise can improve muscle size and strength—perhaps not as well as high-intensity exercise, but enough to show a benefit to study subjects such as older adults or those with injuries or diseases that preclude them performing high-intensity exercise. Blood flow-restricted exercises did not appear to cause vascular issues, such as blood clots or stiffened arteries. Now, Russ and Clark want to know whether blood flow-restricted exercise and other novel therapies such as electrical muscle stimulation can increase the ability of proteins to release the calcium that muscles need to contract.
These are just some of many questions that OMNI researchers expect will keep them busy in their labs into the next decade. If OMNI researchers can discover the “whys” of certain musculoskeletal and neurological disorders, they can eventually develop appropriate therapies, ranging from specific types of exercise to manipulation and pharmacological solutions. Judging from the dire picture painted by the most recent economic and disability statistics, OMNI’s work has the potential to be a relief to aching backs and strained health care budgets everywhere.
Sidebar: Case of the Nerves
Aside from muscle strength and aches, OMNI scientists are involved in several projects that explore the origins of medical conditions—from the common to the rare—in the nervous system.
Thad Wilson, an associate professor of biomedical sciences in the College of Osteopathic Medicine who is one of the five principal OMNI investigators, studies the role of the autonomic nervous system in the common skin disorder rosacea. Individuals with rosacea experience facial flushing activated by changes in skin blood flow. The condition can be triggered by events such as hot and cold weather extremes or emotional stress, which are associated with the “fight or flight” stressors that increase nervous activity to the skin. Wilson’s research, funded by the National Rosacea Society, is exploring whether individuals with rosacea have higher sympathetic nerve activity in the facial region. The findings could help identify new therapies and possibly prevent progression of the disease.
Clark, Wilson, Thomas, and Russ are looking to the neurological origins of a very rare condition as well. Mal de debarquement syndrome is a balance disorder that occurs in a small percentage of people after travel, such as on an ocean cruise or long flight. These individuals continue to experience a phantom sense of motion that may persist for months or years. The mechanics of this condition are poorly understood, but the symptoms—dizziness, confusion, fatigue, anxiety—can be debilitating. With a grant from the Mal de Debarquement Syndrome Balance Disorder Foundation, the OMNI team is using transcranial magnetic stimulation to assess the excitability of a subject’s motor cortex. The scientists also will explore the ability of the patients’ autonomic nervous systems to adjust to certain environmental conditions. Because the condition is so rare, subjects have traveled from as far as California and Canada to participate in the research, Clark says. The project aims to identify differences in brain and nervous system activity in these patients, which could help with future diagnosis and treatment.
By Karen Sottosanti
This article appears in the Spring/Summer 2011 issue of Perspectives magazine.
Editor’s Note: In late April, the Osteopathic Heritage Foundations awarded a $105 million gift to the Ohio University College of Osteopathic Medicine. A portion of the funding will support a new research facility for OMNI. For more information, visit: http://www.oucom.ohiou.edu/News/press/heritage_gift/index.htm.