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46 muscle function in terms of Muscle Tension, 46-1 muscle function in…
46
muscle function in terms of
Muscle Tension
Tension can either be
Passive
tension developed in the parallel elastic component of a muscle
(No energy required)
Created by lengthening the muscle beyond the slack length of the tissues
When the muscle is lengthened passive component can add to the
active tension
When muscle is shortened, it can become slack and not contribute to the total tension
Active:
tension developed by the contractile elements of the muscle
(Energy required)
Initiated by the cross-bridge formation and movement of the thick and thin filament
Dependent on
neural factors (frequency, number and size of motor units that are firing)
and mechanical properties of the muscle fibers
(isometric length-tension relationship and
force-velocity relationship)
46-1
muscle function in terms of
Isometric length-tension relationship
Direct relationship with
Plateau
Optimal length at which maximal
active tension is developed by sarcomere
Isometric tension decreases
as muscle is
lengthened
as fewer cross bridges can be
formed.
Tension decreases
as the muscle is
shortened
because of interdigitation of thin
filament (Ascending)
Total tension = Active and Passive together
isometric tension
development in
a muscle fiber and the
length of sarcomeres in a muscle fiber.
46-2
muscle function in terms of
Force-velocity relationship
Speed of shortening of myofilaments
The rate at which the myofilaments are able to slide
past one another and form and reform cross bridges
(changes length basically)
Force-Velocity relationship describes the relationship between
velocity of the muscle contraction
and the
force produced
For dynamic contractions Force Velocity relationship
should be combined with Length tension relationship as
Human movements does not occur at a constant velocity
In Concentric contraction
– Force and velocity has an
inverse relationship
In Eccentric contraction
– Force and velocity has a
direct relationship