Control Of Mechanical Output Flashcards
What are features of structures acting in parallel?
Forces add up
Each element only feels part of the force
Movements don’t add up
Each element experiences the whole movement
What are features of structures acting in series?
Forces do not add up
Each element feels only part of the whole force
Movements add up
Movement is shared between the elements
What is the optimal sarcomere length for force generation?
2-2.5micrometers
Features of the length tension relationship at sarcomere level and higher as well as commenting on passive and active force.
At sarcomere level, relationship due to degree of overlap between thick and thin filaments.
Above this level, more complex relationship due to non uniformity of sarcomere length along muscle.
Passive tension due to elastic elements - resting muscle, unstimulated.
Active tension is the extra force due to cross bridges
Define the strength of a muscle.
The amount of force (N) that can be generated under isometric conditions during a single maximum voluntary contraction.
Isometric muscle force is proportional to the number of attached cross bridges in parralel
What are the determinants of muscle strength?
Physiological CSA Anatomical CSA Angle of pennation Muscle length Mechanical advantage of joint Neural activation Antagonist co-contraction Hormones Temperature Fibre type
Explain 3 types of muscular contractions
Isometric; no change in muscle length
Concentric; muscle is actively shortening
Eccentric; muscle is being actively lengthened
Explain isokinetic, isotonic and isoinertial.
Isokinetic; constant velocity of shortening
Isotonic; constant force
Isoinertial; neither constant force or velocity
What is power?
A function of muscle volume
Rate of doing work
Force x velocity
Why does force decrease with increasing velocity?
Decreased time for attachment
S2 segments of X bridge will be less stretched - apply less force
Proportion of X bridges will be carried into a position where they OPPOSE movement.
