Muscle Mechanics Flashcards
Cross bridges produce muscle force
Force production results from the interaction between myosin
heads (thick filaments) and actin binding sites (thin filaments)
Proposed cross-bridge explanation
Passive force originates from elastic recoil of
muscle after stretch via connectin filament
Muscle length during squats
soleus- lengthens
gastrocnemius- lengthens and shortens so remains fairly consistent through movement
active insufficiency
When a muscle becomes shortened to the
point that it cannot generate or maintain
active tension
Summary of length and force relationship
A muscle’s ability to produce active force decreases when
either short or long
* Proposed to occur due to extent of cross-bridge formation that
can occur
* Active insufficiency is when a muscle becomes shortened to
the point that it cannot generate or maintain active tension.
* When dealing with biarticular muscles, joint position can be
used to manipulate muscle contribution
passive insufficiency
When an opposing muscle becomes stretched to
the point where it can no longer lengthen and
allow movement
Summary of passive insufficiency
Muscles have a finite length
* Antagonist muscles relax to allow joint movements
* The length of an antagonist muscle can limit the range of
movement
* When dealing with biarticular muscles, the muscle may
already be in a lengthened position from the first joint
action
* Passive insufficiency occurs when that muscle reaches its
maximum length before second joint action is fully
performed
relationship between muscle velocity and force
summary-
Force production is dependent on the velocity of movement
* For the same muscle length, concentric contractions generate
less force than isometric or eccentric contractions
* The force output drops as the movement velocity increases
* Proposed to occur though the extent of cross-bridge formation
that can occur
