CH2: Biomechanics of Resistance Exercise Flashcards
proximal attachement
origin
distal attachement
insertion
toward the center of the body
proximal
away from the center of the body
distal
what is the pivot point of a lever?
fulcrum
what is a first class lever?
muscle force and resistive force act on opposite sides of the fulcrum
mechanical advantage
a ratio of the product of muscle force and the moment arm through which it acts, and the resistive force and the moment arm through which it acts, that is greater than 1.0
what is a second class lever?
muscle force and resistive force acting on the same side of the fulcrum, with the muscle force acting through a much longer moment arm
what is a third class lever?
muscle force and resistive force act on the same side of the fulcrum; with the muscle force acting through a much shorter moment arm
what is torque (equation)
torque = force x moment arm (distance)
how does bone insertion effect strength?
the further away from the joint center tendons are inserted on bone, the longer the moment arm through which muscle acts and therefore the heavier you can lift
how does bone insertion effect speed?
the further away from the joint center tendons are inserted on bone, the more the muscle has to contract to make the joint move through a given range of motion
left-right anatomical plane
sagittal
front-back anatomical plane
frontal
upper-lower anatomical plane
transverse
ability to exert force
strength
define work
force x distance
define power
time rate of doing work ( P = w/t )
how do you get a weight into SI units
multiply the mass (kg) by the local acceleration due to gravity (9.8m/s^2)
what happens during recruitment?
the determining of which and how many motor units will be involved in a muscle contraction by neural control
rate coding
rate at which motor units are fired
what makes a muscle contraction stronger?
number of motor units, size of motor units, rate of firing of motor units
pennate muscle
fibers aligned obliquely with the tendon, creating a featherlike arrangement
how does the angle of pennation effect strength and velocity of shortening?
greater pennation = greater force, lower shortening velocity
lesser pennation = lesser force, greater shortening velocity
muscle shortens because the contractile force is greater than the resistive force
concentric
muscle lengthens because the contractile force is less than the resistive force
eccentric
muscle length does not change since the contractile and resistive forces are equal
isometric
what is the classic formula to standardize loads lifted across body sizes?
load lifted divided by body weight to the 2/3 power
product of the accelerating force and the mass of the body being accelerated
inertial force
bracketing technique
using lighter than normal and greater than normal resistance for a specific movement
what does low resistance bracketing do?
allow a greater speed of movement, training the neuromuscular system to operate within that desired speed and acceleration range
what does high resistance bracketing do?
develops greater force during acceleration at a lower speed, helps with force production
formula for frictional force
F = coefficient of friction x normal force
what are the two components of fluid resistance?
surface drag and form drag
surface drag
friction of a fluid passing along the surface of an object
form drag
how fluid presses against front or rear (frontal cross sectional area) of an object
where are you most likely to get a back injury
lower two lumbar vertebrae, and between the lowest lumbar vertebrae and the top of the sacral vertebrae
lordotic
curved inward
kyphotic
rounded
what does the Valsalva Maneuver do?
creates a rigid compartment of liquid in the lower torso and air in the upper torso which increases the rigidity of the entire torso
