Chp 2 Biomechanics of Resistance Exercise Flashcards
First Class Lever
Example
a lever for which the muscle force and the resistive force act on opposite sides of the fulcrum
Triceps Extension
Mechanical Advantage
the ratio of the moment arm of through which an applied force acts to that through which a resistive force acts
Mechanical Advantage > 1;
Mechanical Advantage < 1
Mechanical advantage
Mechanical disadvantage
Second Class Lever
Example
a lever for which the muscle force and the resistive force act on the same side of the fulcrum, with the muscle force acting through a longer moment arm than that of resistive force –> mechanical advantage > 1
Standing Heel Raise
Third Class Lever
Example
a lever for which the muscle force and the resistive force act on the same side of the fulcrum, with the muscle force acting through a moment arm shorter than that through which the resistive force acts –> mechanical advantage < 1
Biceps Curl
Isaac Newton’s Second Law
F = m * a
Work
Work = Force * Displacement
Power
Power = The time rate of doing work
= Work/Time
= Force * Velocity
Angular Displacement
the angle through which an object rotates
Angular Velocity
the object’s rotational speed (rad/s)
Rotational Work
Rotational Work = Torque * Angular Displacement
Neural Control: Recruitment & Rate Coding
When is muscle force greater?
a) more motor units are involved in a contraction
b) motor units are larger in size
c) the rate of firing is faster
Joint Angular Velocity
Concentric/Eccentric/Isometric muscle action
Concentric: contractile force > resistive force
Eccentric: contractile force = resistive force
Isometric: contractile force = resistive force
During isokinetic (constant-speed) concentric exercise, torque capability _____ as angular velocity _____ .
declines; increases
During eccentric exercises, as joint angular velocity _____ , maximal torque capacity _____ until about 90 degree/s, after which it _____ gradually.
increases; increases; declines
