Muturi Muriuki's pictureMuturi Muriuki

Hope College

Dr. Thelen

Supported by NIH (University of Michigan)

Over the past summer I was involved in Biomechanics Research, for the second year in a row, with Dr. Thelen. I was involved in the processing of data that we collected at the University of Michigan Biomechanics Lab last year.

The data that we took was the forceplate and 3D tracking data of various subjects taking a step to recover from a forward lean. The tracking was done using an optical system, Optotrak (tm), that triangulated the positions of several infrared emitting markers placed at various joint locations on the body of the subject. The forceplate data records the moments and forces in three perpendicular directions under each foot. We also took EMG data from several muscle groups.

The processing involved the determination of the angles of body segments during the taking of the step. The segments are the lower and upper leg, both right and left sides, and the torso. Since all the markers were not visible all the time during the acquisition of data, I had to write a program to splice missing data points. The angle data is then sent to Working Model (tm) to try to determine the torques and forces produced by the various muscles. This inverse dynamics was done by Bill Day. The EMG data was used to determine the onset time of muscle activity, and comparisons were made between the two age groups that were the test subjects.

muriukim@hope.edu