This
thesis
presents
a
musculoskeletal
model
that
predicts
the
muscle
and
joint
forces
in
the
upper
limb
during
an
extreme
activity.
The
scapula
is
an
important
link
in
the
kinematic
and
dynamic
chain
of
the
upper
limb;
with
its
muscles
acting
as
the
primary
stabilisers
to
the
inherently
unstable
glenohumeral
joint,
thus
allowing
effective
transmission
of
load
through
the
kinematic
chain
of
the
shoulder.
This
bone
is
poorly
represented
in
musculoskeletal
models
during
these
activities.
Large
soft-‐tissue
artefacts
are
a
key
reason
for
this.
The
shoulder
is
particularly
prone
to
injury
in
overhead
activities
of
the
upper
limb.
Heavily
loaded
activities
in
these
positions
are
of
interest
because
they
represent
a
limit,
in
that
few
people
are
capable
of
performing
them.
Pull-‐ups
are
a
common
training
activity
that
involve
the
movement
of
a
large
load
with
the
arms
overhead.
Predicting
the
forces
involved
in
such
an
activity
allows
a
testing
of
current
model
limits
and
hypotheses
on
the
function
and
biomechanics
of
the
scapula.
A
novel
methodology
to
track
the
dynamically
moving
scapula
is
validated
using
motion
capture
technology.
This
method
is
shown
to
improve
measurement
accuracy
when
compared
to
the
literature.
Kinematics
of
the
scapula
and
upper
limb
are
thus
measured,
presented
and
discussed
for
three
types
of
pull-‐up
activity.
The
modelling
aspects
of
the
work
build
on
a
previous
upper
limb
model,
primarily
adapting
the
kinematics
representation.
This
better
respects
the
measured
kinematics
through
a
relaxation
of
the
closed-‐chain
mechanism
as
well
as
improving
the
ability
to
non-‐homogeneously
scale
the
model.
The
inverse
dynamics
description
is
modified
to
allow
a
variable
hand
load,
muscle
wrapping
parameters
and
changed
to
prevent
sudden
unphysiological
changes
in
moment
arms
and
muscle
bounds
are
increased
to
allow
equilibrium
to
be
reached
with
the
inter-‐segmental
moments.
Musculoskeletal
loads
are
thus
presented
using
a
model
that
allows
the
dynamic
analysis
of
extreme
activities.
Eccentric
loading
of
the
supraspinatus,
deltoid
and
triceps
was
found
to
exist
in
potentially
vulnerable
positions,
coinciding
with
a
high
incidence
of
impingement
injury
in
pull-‐up
type
activities.
The
glenohumeral
joint
reaction
force
is
seen
to
be
more
centralised
with
a
general
increase
in
rotator
cuff
activation,
although
teres
major
and
posterior
deltoid
seem
to
be
key
stabilisers.
Pectoralis
major
was
detrimental
to
stability,
highlighting
the
importance
of
the
scapula
in
positioning
muscles
during
overhead
activities.
Comparison
of
model
predictions
with
literature
EMG
results
show
good
agreement
