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Hello from Canada!
I am a second year masters student completing my thesis
on the development of complex motor skills using infants (6- to 12- months
of age) as a subject population. For my analysis, I need the following
information: segment mass, center of gravity location and radius of
gyration of the foot, shank, thigh, lower and upper trunk. I have
acquired several papers that deal with this topic:
Hatze, H. (1980). A mathematical model for the computational
determination of parameter values of anthropometric segments. J. of
Biomechanics. 13: 833-843.
Jenson, R.K. (1978). Estimation of the biomechanical properties of
three body types using a photogrammetric method. J. Biomechanics. 11:
349-358.
Schneider and Zernicke. (1992). Mass, center of mass and moment of
inertia estimates for infant limb segments. J. Biomechanics. 25(2):
145-148.
Han Sun and Jenson, R.K. (1994). Body segment growth during
infancy. J. of Biomechanics. 27 (3): 265-275.
The problem that I am facing with my data is that I require specific
information regarding the placement of reflective markers on the infants.
For some of the above papers, this information is not clear. To determine
the segment length of the foot for example, what are the best proximal and
distal body landmarks to use (some use the 1st Metatarsophalangeal to
Lateral malleolus of the fibula 1st metatarsal other papers use the distal
joint as the 5th Metatarsophalangeal joint) ?
I have tried to program a basic spreadsheet using the regression
coefficients and equations stated in the Han Sun and Jenson paper (1994),
however I have received some very strange results! To find the segment
mass of the thigh for instance, I used the following equation:
Y= ao + a1X + a2X2 + a3 X3 + a4 X 4
where Y= segment mass in kgs
X= age in weeks of the infant
ao = 2.94021 to the exponent -1
a1= 1.01128 to the exponent of -2
a2 to a4 = 0 and are thus not included in my spreadsheet
calculations for the segment mass of the thigh.
However, when I try this equation for a fictional subject 12 weeks of age,
I find the segment mass to be approximately 11.94302 kgs. Anyone who has
had contact with a 12 week old infant knows that this figure is quite
impossible!
Does anyone have any ideas for why I am not getting realistic information
when I use the equations in the Han Sun /Jenson paper? Alternatively, does
anyone have another paper that has segment mass, center of gravity and
radius of gyration information for infants 6- to 12- months of age? I am
familiar with similar information about adults published in Winter's book
Biomechanics and motor control of human movement. Such a format would be ideal!
As is the custom, I will post any solutions or ideas received! Thank you
for your time!
Sincerely,
Lori Vallis
Biomechanics Masters student
University of Ottawa, Ottawa Canada
E-mail: s603485@aix1.uottawa.ca
I am a second year masters student completing my thesis
on the development of complex motor skills using infants (6- to 12- months
of age) as a subject population. For my analysis, I need the following
information: segment mass, center of gravity location and radius of
gyration of the foot, shank, thigh, lower and upper trunk. I have
acquired several papers that deal with this topic:
Hatze, H. (1980). A mathematical model for the computational
determination of parameter values of anthropometric segments. J. of
Biomechanics. 13: 833-843.
Jenson, R.K. (1978). Estimation of the biomechanical properties of
three body types using a photogrammetric method. J. Biomechanics. 11:
349-358.
Schneider and Zernicke. (1992). Mass, center of mass and moment of
inertia estimates for infant limb segments. J. Biomechanics. 25(2):
145-148.
Han Sun and Jenson, R.K. (1994). Body segment growth during
infancy. J. of Biomechanics. 27 (3): 265-275.
The problem that I am facing with my data is that I require specific
information regarding the placement of reflective markers on the infants.
For some of the above papers, this information is not clear. To determine
the segment length of the foot for example, what are the best proximal and
distal body landmarks to use (some use the 1st Metatarsophalangeal to
Lateral malleolus of the fibula 1st metatarsal other papers use the distal
joint as the 5th Metatarsophalangeal joint) ?
I have tried to program a basic spreadsheet using the regression
coefficients and equations stated in the Han Sun and Jenson paper (1994),
however I have received some very strange results! To find the segment
mass of the thigh for instance, I used the following equation:
Y= ao + a1X + a2X2 + a3 X3 + a4 X 4
where Y= segment mass in kgs
X= age in weeks of the infant
ao = 2.94021 to the exponent -1
a1= 1.01128 to the exponent of -2
a2 to a4 = 0 and are thus not included in my spreadsheet
calculations for the segment mass of the thigh.
However, when I try this equation for a fictional subject 12 weeks of age,
I find the segment mass to be approximately 11.94302 kgs. Anyone who has
had contact with a 12 week old infant knows that this figure is quite
impossible!
Does anyone have any ideas for why I am not getting realistic information
when I use the equations in the Han Sun /Jenson paper? Alternatively, does
anyone have another paper that has segment mass, center of gravity and
radius of gyration information for infants 6- to 12- months of age? I am
familiar with similar information about adults published in Winter's book
Biomechanics and motor control of human movement. Such a format would be ideal!
As is the custom, I will post any solutions or ideas received! Thank you
for your time!
Sincerely,
Lori Vallis
Biomechanics Masters student
University of Ottawa, Ottawa Canada
E-mail: s603485@aix1.uottawa.ca