CH2 musculoskeletal system Flashcards
anatomy definition
the study of components that make up the musculoskeletal machine
biomechanics definition
the mechanics through which the musculoskeletal components interact to create movement
how do muscles function
by pulling against bones that rotate about joints and transmit force through the skin to the environment
can muscles pull or push or both
only pull
what is part of the axial skeleton
cranium, vertebral column, ribs, sternum
what is part of the appendicular skeleton
shoulder girdle,
left and right humerus,
radius and ulna,
carpal, metacarpals, phalanges,
pelvic girdle
left and right femur
patella
tibia, fibula
tarsals, metatarsals & phalanges
what are the types of joints and what mvt do they allow
fibrous joints: no mvt
cartilagenous joints: allow limited mvt
synovial joints: allow considerable mvt
what is the skeletal musculature
a sys of m. enables the skeleton to move
define origin and insertion and what def do we not consider
origin: proximal attachment (not more stationnary)
insertion: distal attachment (not more mobile)
definition agonist and antagonist and synergist
agonist: the muscle most directly involved in bringing about a mvt (prime mover)
antagonist: a muscle that can slow down or stop the movement
synergist: a muscle that assists indirectly in a movement
t/f all muscles of the body act thru levers
false, many m. do not act thru levers
body mvt directly involved in sport and exercise primarily act thru what kind of levers
bony levers
def lever
rigid or semirigid body that, when subjected to a force whose line of action does not pass thru its pivot point, exerts force on any object impeding its tendency to rotate
def torque
rotatory force (moment), is the magnitude of a force times the length of its moment arm. Degree to which a force tends to rotate an object about a specified fulcrum
def mechanical advantage and what does it quantify
the ratio of the moment arm through which an applied force acts to that thru which a resistive force acts
it quantifies how certain orientations affect force and velocity
what happens if MA is over 1.0
allows Fa<Fr to produce an equal amount of torque
is an advantage
favors high strength and low velocity
what happens if MA is under 1.0
allows Fa>Fr to produce an equal amount of torque
is an disadvantage
favors low strength and high velocity
describe a first class lever
Elbow extension against resistance
disadvantage MA<1.0
during isometric exertion or constant speed joint rotation
because Mm<Mr, Fm>Fr
describe a 2nd class lever
plantarflexion against resistance
advantage MA>1.0
when the body is stationary or moving upward at a constant velocity bc Mm>Mr, Fm<Fr
advantage bs a small muscular force is required to move a person’s body weight
describe a 3rd class lever
elbow flexion against resistance
disadvantage MA<1.0
when the arm is stationary or moving upward at a constant velocity because Mm<Mr, Fm>Fr
disadvantage bc a larger muscular force is required to move the resistance
how does the patella affect the MA of the quadriceps
it increases the MA of the quads by maintaining the quad tendon’s distance from the knee’s axis of rotation
relationship btw moment arm and mechanical advantage
the moment arm varies thru the joint’s ROM. when the M is shorter, there is less MA
as a weight is lifter, the M thru which the weight acts, & thus the resistive torque changes with the horizontal distance from the weight to the elbow
based on the MA equation what do most of the skeletal muscles operate at
considerable mechanical disadvantage
what is the primary lever orientation in the human musculoskeletal sys
3rd class 95%
humans are more built for strength or speed
built more for speed than strength
during sports or activities forces in the muscles and tendons are lower or higher than those exerted by the hands or feet on external objects or the ground
much higher
is it more important to understand the principle of Ma or classifying the lever
MA is more important than lever classification
tension insertion farther from the joint center
results in the ability to lift heavier weight
results in loss of max speed and reduces the muscle’S force capability during faster movement.
what occurs with a larger moment arm and torque
larger moment arm and thus greater torque for a given muscle force, but less rotation per unit of muscle contraction and thus slower movement speed
diff btw closer tendon insertion and further
closer: faster and weaker
further: stronger and slower
in what plane is the
standing barbell curl
sagittal
what plane is the lat dumbbell raise
coronal
what plane is the dumbbell fly
transverse
what plane is curl ups
sagittal
what plane is standing heel raise
sagittal
what plane is leg extension
sagittal
what plane is bench press
transverse
what plane is triceps pushdown
sagittal
what is the most important def of strength
capacity to exert force at any given speed
what is the def of power
time rate of doing work
mathematical product of force and velocity at whatever speed (high speeds is not the correct definition from scientific perspective)
what are the biomechanical factors in human strength (9)
neural control
muscle cross-sectional area
arrangement of muscle fibers
muscle length
joint angle
muscle contraction velocity
joint angular velocity
strength to mass ratio
body size
according to neural control component, muscle force is greater when…
more motor units are involved in cnt
motor units are greater in size
rate of firing rate is faster
explain the muscle cross-sectional area
the force a muscle can exert is related to its CSA rather than its volume
what muscle pairs will generate the same amount of force (CSA vs length)
2 muscle that have the same CSA but different lengths or diff volumes
t/f 2 muscles of equal weight and volume with one muscle longer than the other will generate the same amount of force
false
def arrangement of m fibers
variation exists in the arrangement and alignment of sarcomeres in relation to the long axis of the muscle
what is the arrangement of fibers in pennate muscles
a muscle with fibers that align obliquely with the tendon, creating a featherlike arrangement
what is the angle of pennation
angle btw the muscle fibers and an immaginary line btw the m.’s origin and insertion
what is the most often seen angle of pennation
under or equal to 15°
as long as a muscle’s CSA remains the same, an increase in pennation will allow the muscle to do what
to generate a greater amount of force than nonpennate muscle
results in a lower maximal shortening velocity than nonpennate muscles
when can a muscle generate its greatest amount of force
when it is at its resting length or near its resting length
when the m. is stretched beyond or contracted below its resting length what happens to the tension and what theory explains it
generates less tension
explained by the sliding filament theory
the amount of torque that can be exerted about a given body joint varies thru a joint’s ROM and depends on (6)
-F vs m. length relationship
-variation in leverage attributes to dynamic geometry of the m., tendons and internal joint structures
-the type of exercise
-the body joint in question
-the muscles used at that joint
-speed of cnt
define the force velocity relationship (explain, linear/nonlinear, when is decline the steepest)
-force capability of the m. decreases as the velocity of cnt increases
-as the velocity of mvt increases the max force a m. can produce concentrically decrease
-not linear relationship
-the decline is the steepest when speed is increasing from slow to mod and less steep when speed is increasing from mod to fast
t/f eccentric produces less F and requires more E than concentric
false, more F produced and requires less E
define the relationship btw force-velocity and power (who uses it, how is the curve moved in a perfect program)
used by sport scientists and strength and conditioning coaches to design effective strength and power training programs
force velocity curve to the R and power curve upwards
muscle torque varies w joint angular velocity according to what
type of muscular action like concentric, eccentric and isometric
what is the torque and angular velocity relationship for
-isokinetic concentric exercise
-eccentric exercise
-isokinetic-concentric: torque capability declines as angular velocity increases
-eccentric: max torque capability increases until about 90°/s after which it declines gradually
muscle force for eccentric, concentric and isometric in order
eccentric>isometric>concentric
strength to mass ratio definition
equals the force a person’s m. can exert during a particular mvt divided by the mass of the body and it reflects an athlete’s ability to accelerate their body
strength to mass ratio is important in what sports
sprinting, jumping and weight classification
what happens to a sprinter’s ability to accelerate if he or she increases body mass and force capability by 15% and 10%, respectively
they will slow down
which of the following wrestler’s has a decided advantage in strength
-A; higher strength, body wieght 200 lb
-B: lower strength, body weight 200 lbs
A is stronger
is the strength to mass ratio of larger athletes higher or lower than that of smaller athletes
gymnasts are stronger athletes pound for pound (smaller athletes have a higher strength to mass ratio than does the larger athlete)
as body size increases what happens to body mass and muscle strength
body mass increases more rapidly than does muscle strength
a muscle’s contractile force is fairly proportional to its…
CSA and its related to the square (2nd power) of linear body dimension
a muscle’s mass is proportional to its …
volumes and its related to the cube of linear body dimensions
what are the most common sources of resistance to muscle contraction
gravity, inertia, friction, fluid resistance, elasticity
whats always constant for gravitational force and moment arm
grav F: on an object always acts downward
moment arm: of a weight is always horizontal
how would you apply gravity to resistance exercise training (weight is closer, further from joint and effect on resistive torque)
-during a fw exercise, the weight doesnt change by the length of the moment arm changes
-when weight is horizontally closer to the joint, it exerts less resistive torque
-when the weight is horizontally further to the joint, it exerts more resistive torque
in weight stack machines, what is the source of resistance and what does the machine provide
gravity is the source of resistance
machine provides increased control over the direction and pattern of resistance
what varies when using a cam-based weight stack machine
moment arm of the weight stack varies during the mvt
def inertia
-tendency of a body to resist acceleration
-is the tendency of a body at rest to remain at rest or of a body in motion to stay in motion in a straight line unless disturbed by an external force
can act in any direction
application of inertia to upward phase of biceps curl
-must overcome gravitational and inertia F to move the barbell upwards
-at the start, the bar is accelerated from a zero velocity to an upward velocity
-near the top of the exercise, there is some deceleration to bring the bar’s velocity back to zero
-early in the ROM, the agonist muscles receive resistance in excess of the bar weight
-toward the end of the ROM, the agonist muscles receive resistance less than the bar weight
what are examples of explosive exercises in forms of acceleration training
snatch, clean and jerk, power clean, high pull
what is the bracketing technique
a sport movement is performed with less than normal and greater than normal resistance
what is friction
is the resistive force encountered when one attempts to move an object while it is pressed against another object
application of friction to resistance exercise training in example a football lineman pushes a weighted-sled
-it takes more force to initiate the sled’s mvt than to maintain its initial movement because the coefficient of static friction is always > than the coefficient of sliding friction
-must overcome the resistance due to the sled’s inertia (directly proportional to the sled’S mass and acceleration)
-must also overcome the resistance due to the friction btw the sled’s runners and the ground (proportional to the friction coefficient btw the contact surfaces and the net force pressing against the sled)
what is fluid resistance
resistive F encountered by an object moving thru a fluid, or by a fluid moving past or around an object or thru an orifice
what are the 2 sources of fluid resistance
surface drag: results from the friction of a fluid passing along the surface of an object
form drag: results from the way in which a fluid presses against the front or rear of an object moving through it
application of fluid resistance exercise training with fluid resistance exercise machines
-most often use cylinders in which a piston forces fluid thru and orifice
-allow rapid acceleration early in the exercise movement
-allow little acceleration after higher speeds are achieved
-cannot perform isokinetic exercise on theses machines
-do not generally provide an eccentric exercise phase, although machines with an internal pump do
application of elasticity to resistance exercise training
-the more that the band is stretched, the greater the resistance
-the exercise movement begins with low resistance and ends with high resistance
-the adjustability of the band’s resistance is limited
back, back injury and intra-abdominal Pressure and lifting belts
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