Jul 16, 2013

Webinar: All Models Are NOT Wrong (Contrary to Popular Belief)

Wendy Murray discusses how models can integrate experimental data from different studies to lead to a deeper understanding of human movement, using two recent studies of the upper-limb as case studies.

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Title: All Models Are NOT Wrong (Contrary to Popular Belief)
Speaker: Wendy Murray, Northwestern University
Time: Tuesday, July 16, 2013 at 9:30 a.m. Pacific Daylight Time


In Dr. Murray's laboratory, biomechanical modeling and simulation serve as methodological tools that advance the types of questions they can ask about upper limb function. The upper limb extends from the shoulder to the hand, and includes the shoulder, elbow, forearm, and wrist joints, as well as an additional 15 joints in the fingers and thumb. Completion of activities of daily living often involves postural changes at multiple joints simultaneously, and the challenge of coordinating functional movements is further complicated by the fact that many of the muscles in the upper limb cross and actuate multiple degrees of freedom. Understanding the functional use of the upper extremity demands a holistic approach. For instance, over 80% of activities of daily living involve grasping objects with the hand [1], and the ability to produce force with the hand is directly related to the ability to maintain an extended wrist [2]. Further, persons with cervical spinal cord injuries who retain active control of elbow extension are more independent in self-care tasks than individuals with functioning wrist extension who lack active elbow extension [3]. Biomechanical modeling together with both static and dynamic simulation techniques plays a critical role in the advancement of our understanding of function in the upper limb, with and without impairment.

In this webinar, Dr. Murray will highlight two recent studies ([4], [5]) in which they used biomechanical simulation to gain important insights that would have been difficult (or impossible) to derive from the existing experimental data alone. In doing so, she hopes to highlight the value of simulation studies and advocate for well-designed, simulation approaches to advance our understanding of human movement.

[1] S. Katz, T. D. Down, H. R. Cash, and R. C. Grotz, "Progress in the Development of the Index of ADL," Gerontologist vol. 10, Spring 1970, pp. 20-30.
[2] S. W. O'Driscoll, E. Horii, R. Ness, T. D. Cahalan, R. R. Richards, and K. N. An, "The relationship between wrist position, grasp size, and grip strength," J Hand Surg Am. vol. 17, Jan 1992, pp. 169-77.
[3] R. D. Welch, S. J. Lobley, S. B. O'Sullivan, and M. M. Freed, "Functional independence in quadriplegia: critical levels," Arch Phys Med Rehabil vol. 67, Apr 1986, pp. 235-40.
[4] S. J. Wohlman and W. M. Murray. "Bridging the gap between cadaveric and in vivo experiments: A biomechanical model evaluating thumb-tip endpoint forces." J Biomech vol. 46 pp. 1014-1020, 2013.
[5] X. Hu, W. M. Murray, E. J. Perreault. "Muscle short-range stiffness can be used to estimate the endpoint stiffness of the human arm." J Neurophysiol vol. 105, pp. 1633-41.

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