module 3: section 3
What is an agonist
the muscle primarly responsible for a movement
what is an antagonist
the muscle that opposes the movement of the agonist
what is reciprocal contraction (or activation)
the simultaneous actrivation of the agonist and inactivation (relaxation) of the antagonist
what is co-contraction
simultaneous activation of the agonist and antagonist
benefits of reciprical contraction (or activation)
maximizes the amount of force the agonist produces
benefits of co contraction
allows us to stabilize the movement very effectiveely
agonist of knee and hip
knee is quadriceps, hip is gluteus maximus
when is the movement eccentric vs concentric
eccentric is lengthening of the muscle, concentric is shortening of the muscle. Eccentric occurs when movement is with gravity (towards the ground)
what is biomechanics
the study of the effects and control of the forces that act on and are produced by living beings
what is kinematics
the study of the motion of objects (without reference to the forces that caused the motion)
what is kinetics
the study of forces that cause motion
what is a force
an action of influence that moves the body or influences the movement of the body. Internal forces are created primarily by skeletal muscles. External forces are created by the ground, external loads, other individuals.
What is a moment?
a force that tends to change the rotational motion of an object (NxM)
Is the moment positive or negative clockwise vs counter clock wise
clockwise is negative, counter clock wise is positive
The force of gravoty acts on which direction through the centre of mass of an object
downward (-y)
What is the center of mass (COM)
the point in an object where mass of the object is equally distributed in all directions
force of gravity formula
Force = mass x acceleration(gravity, 9.8m/s^2)
moment formula
Moment = Force x distance
if a segment in stationary, what does the sum of all moments equal
M=0
How to take measurements in kinematics (4)
1. visual observation
2. goniometer - instrument to measure angles
3. inertial sensors
4. optical or magnetic motion capture
How to take measurements in kinetics (3)
1. manuel assesment
2. Dynamometer - device to mesure force, moment or power
3. Force plates - instrument to measure group reaction forces