Hello Biomch-L readers,

I am in need of some information regarding the force-length and
force-velocity properties related to spastic muscle, particularly related
to children with Cerebral Palsy. I am interested in modelling dynamic
contraction of muscle based on EMG values and force as a function of
muscle velocity and length. Apparently from readings, CP muscle will
have different properties (ie. shorter muscle, longer tendon, higher
distribution of type-I fibres, and fewer sarcomeres in series). I
initially planned on using dimensionless curves of FL and FV as proposed
by Zajac (1989) and recently available on the Biomechanics Web site (ISB)
from Scott Delp.

I would like some clarification as to whether these dimensionless curves
are applicable to the case of spastic (cp) muscle, and if they are how
might they be scaled. If these curves are not applicable to the spastic
muscle, is there anyone that has this data or know of its publication?

One other question of note, is if the dimensionless Force-Velocity curve
is scaled or proportional to the percentage of slow/fast fibres.


Zajac, F.E. (1989) Muscle and tendon: properties, models, scaling and
applications to biomechanics and motor control. CRC Crit Rev Biomed Eng

O'Dwyer, N.J. et al. (1989) Mechanisms of muscle growth related to
muscle contracture in cerebral palsy. Dev Med Child Neurol 31, 543-552.

Dietz, V., and Berger, W. (1995) Cerebral Palsy and Muscle
Transformation. Dev Med Child Neurol 37, 180-184.

Rose, J. et al. (1994) Muscle pathology and clinical measures of
disability in children with cerebral palsy. J. Orthop. Res 12:758-768.


Alan Morris, MASc.
Research Engineer - Gait Laboratory
Bloorview MacMillan Centre
350 Rumsey Road
Toronto, Ontario
Tel (416) 425-6220 x3508
Fax (416) 425-1634
email morrisa@ecf.utoronto.ca