Date: February 13, 2009
Speaker: Tom Kepple (HNES)
Title: Induced Acceleration: Introduction and Applications
Time: 3:30 - 4:30 (refreshments prior)
Location: Townsend 009
Abstract: Traditional inverse dynamics methods for analyzing human movement compute the net moments generated by muscles crossing a joint, leading to the assumption that these moments are the primary controllers of movement at that joint.
Zajac and Gordon (Exer. Sport Sci. Rev, 1989) used a simple planar model to demonstrate that the gastrocnemius muscle, traditionally considered a knee flexor and ankle plantar flexor, can in certain circumstances produce a net knee extension effect. This classic example of induced acceleration analysis shows that muscle groups crossing a joint will act to accelerate all the joints of the body and not just the joints they cross. This model also demonstrated that the magnitude of the resulting accelerations is a function of both the magnitude of the muscle forces as well as the position of all of the joints in the body.
Today’s BIOMS seminar will begin by using a variation of the Zajac and
Gordon model to introduce the underlying principles and equations of induced accelerations analysis. The seminar will then go on to illustrate the utility of the approach by showing how induced accelerations analysis has been applied in four diverse areas of research: 1) clinical cases, 2) determining the sources of forward velocity in a pitched baseball, 3) the computation of muscle induced accelerations per unit activation to assess individual muscle capacity and 4) examination of multi-joint coordination in a functional arm reaching movement.