April 03, 2024 | Anna Flanagan
According to an article published in 2020 in Clinical Rehabilitation, up to 71 percent of manual wheelchair users report that they have experienced shoulder pain at some point in their lives. There is no question that manual wheelchair propulsion puts stress on the upper extremities. But if the pain is related only to the repetitive motion of wheelchair propulsion or overuse, why don’t all manual wheelchair users experience shoulder pain? Why are adults who began using a wheelchair in adulthood more likely to experience pain than adults who began using a wheelchair in childhood, despite significantly fewer years of wheelchair use? Why do female wheelchair users experience shoulder pain at twice the rate and intensity of males? What are the most effective ways of treating shoulder pain? What role does physical activity play in reducing pain and pathology?
These are some of the questions two of the newest scholars in the Department of Kinesiology and Community Health hope to answer through their research. Assistant Professors Matt Hanks and Josh Leonardis joined KCH last fall. Both had just completed post-doctoral research fellowships at the University of Wisconsin-Milwaukee in the Department of Rehabilitation Sciences and Technology.
The Biomechanics of Shoulder Pain
As a doctoral student in kinesiology at the University of Michigan who focused on shoulder biomechanics and neuromuscular control, Leonardis had been investigating shoulder morbidities in breast cancer survivors. Treatments for breast cancer are highly invasive to the shoulder joint complex and upper extremity musculature. “There are a lot of downstream effects that are underappreciated because the focus is on beating breast cancer,” he said. “As breast cancer becomes an increasingly survivable disease, the focus needs to shift to what life is like after the fact.” A small percentage of biomechanics literature focuses on the shoulder, he added, because it’s difficult to study.
When he began looking for a post-doctoral position, he wanted to study shoulder biomechanics in a new population in which pain and pathology were ongoing secondary problems. He chose to complete a post-doctoral fellowship in rehabilitation engineering in the Mobility Lab at the University of Wisconsin-Milwaukee, where studies of wheelchair propulsion biomechanics and shoulder pain and pathology in pediatric and adult populations were underway.
“It felt as though I was given the opportunity to contribute toward improving the quality of life of a couple of different populations, and that was important to me.” Leonardis said.
He describes his general research interest as the adaptability of the neuromusculoskeletal system. One question he will pursue is whether the absence of shoulder pain in some wheelchair users with pediatric-onset disabilities and the presence of pain in others is related to adaptations to the neuromuscular and musculoskeletal systems that occur during the transition from childhood to adulthood, a period between the ages of 8 and 21 when bodies grow and change tremendously. He currently is investigating the possibility of sex-specific adaptations during this period that might contribute to females experiencing pain more frequently and more intensely than males. Similarly, he also believes adaptation might explain why pain is more common in people who begin using wheelchairs as adults when compared to adults who began using wheelchairs as children and adolescents.
The Role of Physical Activity
Matt Hanks, who completed his Ph.D. in Kinesiology at Auburn University, had been investigating the biomechanics of sports-related movement, primarily overhead throwing, in adapted and traditional sport athletes. Working as an athletic trainer with wheelchair athletes sparked his interest in understanding the shoulder biomechanics of manual wheelchair users during activities of daily living and in sport and their association with the development of shoulder pain and pathology. He pursued this during his post-doctoral experience in Milwaukee by investigating shoulder biomechanics during wheelchair propulsion and adapted sport among children and adults with spinal cord injuries. His particular focus is on the potential effects of physical activity to mitigate shoulder pain and pathology in manual wheelchair users by examining changes in shoulder musculoskeletal development and biomechanics as a result of engaging in physical activity during childhood and early adulthood.
“Manual wheelchair users, particularly children and young adults, are populations that are largely understudied in the physical activity realm,” he said. “Of the research that does exist, there is not a clear consensus on the benefits and drawbacks of physical activity. Is it helpful or hurtful? How much makes a difference? How much is too much? When should it begin? A lot of the broad questions remain to be answered.”
Hanks believes children and adults perceive physical activity differently, which can impact motivation and adherence to physical activity. Children are typically motivated by the opportunity to play, have fun, and interact with others socially. Adults often are more motivated by aesthetics and health. They want to look or feel better, or their doctor has encouraged them to be more active. Using a manual wheelchair can certainly make engaging in physical activity more complicated.
“Now you introduce the obstacles of accessibility, the need for adapted equipment and facilities, and adapted educators—people who understand you and are qualified to give you sound advice based on research,” Hanks said.
Both Hanks and Leonardis observe that the biomechanical study of manual wheelchair users is relatively young. As techniques and technology evolve, they said, the means for identifying factors that go into shoulder pain and pathologies as well as effective interventions get better and better. They will pursue answers to their various research questions individually and in collaboration. Hanks is the director of the Disability and Movement Biomechanics Laboratory. His team’s multimodal approach to investigating the role of physical activity on shoulder health in manual wheelchair users utilizes motion analysis and biomechanical modeling, diagnostic and quantitative imaging, and upper extremity strength testing. Leonardis directs the Musculoskeletal Morphology and Biomechanics Laboratory, where he and his team investigate the intimate relationship between musculoskeletal structure and function using traditional biomechanical technologies, computational evaluations of neuromuscular control, and quantitative musculoskeletal imaging techniques. They also co-direct the Movement Analysis Laboratory, a state-of-the-art space equipped for the biomechanical evaluation of various populations across the lifespan.
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