Since its first measurement in 1679, the usefulness of the location of whole body centre of
mass (COM) data has progressed from having largely theoretical value into being an
instrument with several diagnostic and applied scientific uses. This thesis describes first the
biomechanical and measurement theory foundation of COM research and then details the
historical development of methods to measure COM location and the various applied uses
of this variable. Original research data presented in this thesis then go on to provide the
first direct measurements of COM movement in walking humans. A second study
quantifies the accuracy of the most commonly used current technique to quantify COM
location (the kinematic segmental method) by determining the limits of agreement between
it and a direct measurement method (the reaction-board), in lying and running subjects. In
the latter studies a novel reaction-board measurement method is developed making use of
life-sized projections of subjects in various stride positions and used to place runners into
recumbent static running positions. These data demonstrate that reaction-board and
segmental methods report COM locations with a mean difference of 1.6cm and agree to
within limits of 6.0cm for the location of COM in recumbent individuals. The final study
described in this thesis compares single COM measurements made using two kinematic
segmental methods (models) to a direct suspension technique of measuring COM location.
The suspension technique used is adapted from the original method of determining COM
location upon which kinematic segmental methods derive their origin. The data show that
both cadaver-derived kinematic models of COM, and kinematic models derived from live
human data, differ from a direct COM suspension method, and that cadaver based estimates
display greater accuracy (agreement with the direct suspension method). This study also
uniquely provides information on the effect of whole body mass, body fat or body water on
the accuracy of segmental models in male subjects.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/5815 |
| Date | 23 October 2008 |
| Creators | McKinon, Warrick |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
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