Muscle Force-Length and Force-Velocity Relationships Flashcards
What are sarcomeres?
Sarcomeres are the basic contractile units of cardiac muscle. They are composed of thick and thin filaments. Fascicles to muscle fibers to myofibers to sarcomere.
Sarcomeres in-series
Number of sarcomeres end on end along length of muscle. Influences contraction velocity.
Sarcomeres in-parallel (side by side)
Number of sarcomeres next to each other across width of muscle. Influences contraction force
Where dies the active component comefrom?
Sarcomeres
What type of tissue is passive component
NON-contractile tissue such as tendons, connective tissue in sarcomeres etc.
3 stages of active force in sarcomere length
Ascending limb
beak
descending limb
(Inverted U)
Stages in the ascending limb
Too much overlap
some overlap
Stages at peak
optimal overlap
Stages in descending limb
some crossbridge attached
no cross bridges attached
What happens when titin is slack?
There is no tension
When the slack is taken there will be tension.
Where on the FL curve are muscles optimal
Different muscles ‘live’ on different segments of the force-length curve.
It has been suggested that muscles of the lower limb occupy the plateau of the F-L curve and are therefore at optimal or near optimal length for force generation during walking.
F-L implications in the gym
High levels of tension (force) stimulate increased protein synthesis & muscle growth. We want to maximise this muscle force in strength training. Standing & seated calf raises both train the plantar-flexors although gastrocnemius force is higher with the muscle at longer lengths as found in the standing calf raise.
Another curve is…
Knee flexor Torque-Joint Angle curves
they may provide an indication of previous and possibly future hamstring injury. Previously injured hamstring often reach peak torque at shorter
muscle lengths due to previous damage and being slightly weaker.
