Dear Biomch-l subscribers:
Thanks to everyone who responded to my request. Below is the Original
inquiry and the list of responses.
Once again thanks to all to contributed.

> Within a general project concerning the evaluation of the shoulder
> musculoskeletal system contribution to propulsion during human swimming, we
> need to know the shoulder rhythm, and more especially the spatial positions
> of the scapula, vs 3D position of the swimmer's arm. After unsuccessfull
> research in the literature, I have to ask to the biomechanical community if
> biomechanical models of the shoulder rhythm is now available and directly
> usable for this purpose. Moreover, are informations available about the
> shoulder rhythm vs the developed moment at the shoulder ?

Hello Pierre,
I don't know how much help this will be but it may narrow your search for
references. In the past couple of years (96-95), a Master's student in
the Dept. of Physiotherapy at the University of Western Ontario, (London,
Ontario, Canada) looked at the strength of scapular contraction in
competitive swimmers vs. normals and their swim/lap times. The student's
name was John Marshall, unfortunately I don't know the title of his thesis.
I'm sure it is on file at the university library. He might have some
references relevant to your research. Good luck.

Andrew D. Milne, MSc., P.Eng.
Quality Engineer - Ford St. Thomas Assembly Plant PVT
Tel519)637-5424 Fax:637-5461 email:usfmdtnp@IBMMAIL.COM
Dear Pierre

At the moment I'm finnishing my PhD-thesis in which a major part is
about the kinematics of the shoulder. One of the results is a 3-D
description of the scapulo-humeral rhythm which is soon to be published
in the proceedings of the First Meeting of the International Shoulder
Group, august 26-27, 1996 in Delft, a satalite congress of the ESB.
The 3-D scapular positions have been correlated with the humeral positions
and a regression equation was defined based on 23 humeral postures.
I would be happy to send you a copy of the paper.

Jurriaan de Groot

Jurriaan de Groot |Tel : -31-(0)15-2782156
Lab. of Measurement and Control |Fax : -31-(0)15-2784747
Fac. Mechanical Engineering |E-mail : GROOT@TUDW03.TUDELFT.NL
Delft University of Technology |
| |____/(O----------------------
Mekelweg 2 | |:::::/
2628 CD Delft | |:::/ DUTCH SHOULDER GROUP
The Netherlands | |:/
Dear Pierre,

We have carried out a considerable amount of research in this area.
In particular, we have developed a mathematical model which predicts
the three dimensional position of the scapula for a given three
dimensional arm position. This was based on data obtained by a
palpation technique using polhemus sensors. The full data are in a
PhD thesis of this University (Aiuthor Nicholas D Barnett) and the
work is not yet piublished. Hpowever, if you would like more
information we will attempt to help.

Garth Johnson
Dear Pierre,

I may have some information of interest to you Re. the shoulder
rhythm. My dissertation was on the 3D analysis of the shoulder
rhythm including the effects of various loads and the influence of

In brief, I will tell you that the choice of a linear ,quadratic, or
cubic representation of the rhythm depends on the external
shoulder load. In general a third order polynomial appears to be
the best fit (based on partial F tests of significance of addition of
terms to a linear model from my data)

Second I have measured the spatial orientation of the scapula in
the normal resting shoulder to be as follows:

Given an embedded orthogonal reference frame XYZ with the
positive Z axis directed posterior, the positive Y axis directed
laterally toward the subjects right side along the spine of the
scapula, and the positive X axis directed vertically downward
roughly parallel to the vertebral boarder of the scapula. Then the
mean and SD resting scapular orientations based on three Cardan
sequence rotations (degrees) (n=25) were:

X -37.4 (5.9) ( plane of the scapula)
(where 0 would be pure abduction or coronal plane.( neg is
Anterior to the coronal plane by the right -hand -rule) )

Y -20.6 (5.7) (fore/aft tilt of the scapula)
(where 0 would be no tilt or vertical in the coronal plane)

Z -1.7 (5.2) ( Up/down rotation)
(where 0 is when vetebral boarder of the scapula is parallel to the
midline of the trunk (spine) in upwrite sitting)

95% confidence intervals are:
X -34.9 to 39.9
Y -18 to 23
Z -3.9 to 2.2

Hope this is helpful

Kevin J. Mcquade, PhD,PT
New York Medical College
Valhalla,NY,USA 10595
Dear Pierre LEGRENEUR,

In our model '' Shoulder package for PC " we use the shoulder rhythm which
is based on the work by Högfors et al. 1991, as well as the work by Karlsson
and Peterson 1992.

1. Högfors, C., Peterson, B., Sigholm, G. and Herberts, P. (1991)
Biomechanical model of the human shoulder joint - II. The shoulder rhythm.
J. Biomechanics 24, 699-709.

2. Karlsson, D. and Peterson, B. (1992) Towards a model for force
predictions in the human shoulder. J. Biomechanics 25, 189-199.

Best regards,

Mohsen Makhsous
Biomechanics, Dpt. Pol. Mat.
Chalmers University of Technology
S-412-96 Gothenburg, Sweden
Tel: 46-31-7721294
Fax: 46-31-7721313

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