Muscles in Motion

Stephen Marshall, associate professor of epidemiology and orthopedics in the University of North Carolina’s Schools of Public Health and Medicine and biostatistician at UNC’s Injury Prevention Research Center, expected to analyze his research findings at his personal computer until he heard about the visualization wall at RENCI’s Health Sciences Collaboration Center.
Instead, he was able to display multiple kinds of research data simultaneously on the 8-foot by 10-foot tiled display wall in the Collaboration Center, and the results were better than expected.

“The visualization wall adds a whole new dimension to presenting research.  It’s useful for communicating the discovery in addition to analyzing results,” said Marshall. “The visualization capability is amazing; the images are clearer than a regular monitor.”

Marshall is the principal investigator for JUMP-ACL (Joint Undertaking to Monitor and Prevent ACL Injury,, a collaborative multi-site study of neuromuscular risk factors for anterior cruciate ligament (ACL) injury. The ACL is one of the four main ligaments surrounding the knee, and tears or ruptures of this ligament are common in athletes, especially female athletes.  Funded through a grant by the National Institutes of Health, the study includes subjects from the U.S. Military Academy in West Point, NY, the Naval Academy in Annapolis, MD, and the Air Force Academy in Colorado Springs, CO.

“With assistance from the U.S. Department of Defense, this is the first time these institutions have collaborated on an epidemiologic study,” said Marshall.

The study aims to determine the association between neuromuscular risk factors, including poor jump-landing technique, and ACL injuries. It also looks at the relationship between ACL injuries and gender, since women suffer more ACL injuries than men. The subjects—all incoming cadets at one of the military institutions—undergo a baseline assessment that includes: motion analysis during a jump-landing task; strength assessment; postural alignment assessment; and a questionnaire about their injury history and sports participation.  Darin Padua of UNC’s department of exercise and sport ccience, and senior co-investigator on the grant, designed the baseline assessment protocol uses in the study.
The cadets and midshipmen enrolled in the study are followed through their full four-year academy careers and evaluated for ACL injuries. The study will enroll new subjects through 2008, and will eventually study 5,000 cadets, about 40 percent of whom will be female.

Marshall and his team collect data using MotionMonitor software by Innovative Sports Training. MotionMonitor is a real-time 3D motion capture system designed for use in medical research and other situations where precise measurements of the body and its movement through time are required. The hardware used for the study is The Flock of Birds, a motion tracking device that collects position and orientation
information for up to seven sensors.

Marshall worked with Hong Yi, the RENCI senior visualization programmer at the Health Sciences Collaboration Center, to port MotionMonitor from the desktop to the display wall, and their efforts were largely successful. Whereas with the desktop version of the software, he could view either statistical data or motions captured via the tracking devices, Marshall is now able to view the images and a wide range of statistical data simultaneously on the visualization wall. For example, Marshall and his colleagues can now view a multitude of parameters involved in a jump—from foot and knee rotation to landing technique to hip movement—and compare the data to the actual movement that takes place in real time.

Ultimately, the study should give health professionals, patients, athletes and others a better understanding of how ACL injuries happen and help them make simple changes in how they walk, jump or run in order to prevent these injuries.

Marshall compared the movement of the body to a symphony, with all the muscles moving in concert to achieve a particular result. Trying to study such complicated motion on a standard PC is like trying to hear a symphony by listening to one instrument at a time. The RENCI display wall lets the researchers “hear all the instruments in the symphony” and also makes it easier to explain to non experts what is going on, he said.

“Using the visualization wall will increase my ability to communicate this scientific information to a lay audience,” said Marshall. “It is much easier to be able to show them what is going on than to simply tell them.”

RENCI, in partnership with the Health Sciences Library, implemented the Collaboration Center in 2005 as a venue for users to explore new applications and collaborative projects. The tiled display wall provides a large-format environment for presenting high-resolution visualizations (4,096 x 3,072 pixel native resolution) by tiling together the output from a collection of projectors and linked computers. Multiple projectors allow display of images much larger than those on standard computer display screens. The use of the wall enables researchers to receive an overall picture of a dataset, or study fine details without changing the visible image. For more information see

The JUMP-ACL project is supported by the National Institute of Arthritis and Musculoskeletal and Skin Disorders, National Institutes of Health (NIAMS R01-AR050461001).  Pilot research was supported by the American Orthopedic Society for Sports Medicine. JUMP-ACL is an interdisciplinary collaboration nurtured by the UNC Injury Prevention Research Center.