Experiment Protocol:
IDENTIFICATION OF STRTETCH REFLEX CONTRIBUTIONS TO
JOINT STIFFNESS IN NORMAL AND SPASTIC HUMANS
Purpose:
The objective of this study is:
· 1.Carrying out a test_retest study to find
intrasubject reliability of the dynamic stiffness model of the ankle joint. The
experiment is repeated at two different time for each normal subject.
· 2. Finding the intrinsic and reflex contributions
to pathological muscle tone. The experiment is performed on spastic patients.
Description:
- A custom-fit fibre-glass boot
is used to securely attach the subject's foot to the actuator in the experimental
apparatus described in the consent form.
- Range of Motion. The
ankle is rotated passively from a neutral position towards maximum
dorsiflexion and then towards maximum plantarflexion. Displacement in each
direction is continued until the subject could tolerate no further
movement, i.e. the onset of pain, or until motion of the knee or lower leg
is observed.
- Maximum Voluntary
Contraction (MVC). Subjects are required to generate both dorsiflexing
and plantarflexing maximum voluntary contractions in response to changes
in a tracking stimulus displayed on an oscilloscope. The experiment is run
at the operating point (position) at which good reflex torques can be
generated.
A pseudorandom binary sequences (PRBS) is used
as position input to the ankle joint.
- Displacement Amplitude. The
PRBS amplitude is started at 0.01 rad and increased by 0.005 rad for each
trial up to a maximum amplitude that can be endured by the subject.
- Displacement Frequency. The
PRBS switching interval is started at 75 ms (corresponding to maximum
frequency) and increased by 25 ms for each trial up to 200 ms
(corresponding to minimum frequency.)
- Position Variation. The
experiment is started at the first position in which reflex torques can be
generated. The appropriate amplitude is selected based on the production
of the largest reflex torque. This amplitude is maintained during this
part of the experiment.
- Level of Contraction. Subjects
are asked to generate ankle torques from 50% plantarflexing MVC to 0,
decreasing by 10% PF MVC for each trial. Subjects should match the
feedback torque line with the target signal, both of which are displayed
on the oscilloscope. The appropriate amplitude nad position are selected
based on the production of the largest reflex torque and the endurance of
the subject. This amplitude and position are kept constant during this
part of experiment.
- A part of the experiment,
described in 5 to 7, is run for each subject.
- Usually, the experiment will
last for less than 120 minutes including a 30 - 40 min preparation period.
- Subject may ask for a rest or
withdraw from the experiment at any time.
Notes:
- Suggestions and volunteers
are welcomed!
- Mehdi Mirbagheri is
responsible for modifying and arranging this experiment.
Last modified by Mehdi on March 21,95
Last modified: Thu Feb 27 12:18:41 1997