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Hunter, David
12-04-2000, 11:55 PM
Dear colleagues,
I teach clinical biomechanics to Physiotherapy students and
each year in movement analysis we have a debate that I have
yet to resolve to my satisfaction, despite having reviewed
what I think is the relevant literature. The debate is
about the action of the quadriceps and hamstrings during
the action of sitting to standing or during a step up, and
I wondered if anyone has met and resolved the following 2
problem/s.

1. In sitting to standing the hamstrings are active, their
concentric action is to extend the hip and the hip is
extending, therefore we say that the type of muscle
activity of the hamstrings at the hip is concentric. At the
knee, however, their action would be to flex the knee
concentrically, but the knee is extending, therefore active
'lengthening' may be argued to be occurring in the
hamstrings at the knee which traditionally would be defined
as eccentric muscle activity. Is it correct to say
therefore that the hamstrings are acting concentrically at
the hip and eccentrically at the knee and if so what is the
name for this type of muscle activity? Or is it more
correct to say that the hamstrings are likely ot
be acting isometrically yet joint motion is occurring?

2. In the action of sitting to standing it is usually
accepted that a co-contraction is occurring between the
quads and hams. The second annual debate is around what
balance of muscle activity does there need to be between
two opposing muscles for their activity to be
referred to as a co-contraction as opposed to a
situation where reciprocal inhibition is occurring?

Sorry for the long question/s - any responses will be
posted.

Regards

Glenn Hunter.

----------------------------------------
Hunter, David
Email: David.Hunter@uwe.ac.uk
"University of the West of England"

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