46
muscle function in terms of
Muscle Tension

Tension can either be

Passive

Active:

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

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