Ch. 4 Biomechanics of Resistance Exercise Flashcards
anatomy
encompasses the study of components that make up the musculoskeletal “machine”
biomechanics
focuses on the mechanisms through which these components interact to create movement
axial skeleton
consists of the skull, vertebral column, ribs, and sternum
appendicular skeleton
includes the shoulder (or pectoral) girdle (left and right scapula and clavicle); bones of the arms, wrists, and hands (left and right humerus, radius, ulna, carpals, metacarpals, and phalanges); the pelvic girdle (left and right coxal or innominate bones); and the bones of the lys, ankles, and feet (left and right femur, patella, tibia, fibula, tarsals, metatarsals, and phalanges)
joints
the junctions of bones
fibrous joints
allow virtually no movement, (structures of the skill)
cartilaginous joints
allow limited movement (intervertebral disks)
synovial joints
allow considerable movement (elbow and knee)
hyaline cartilage
covers bone ends
synovial fluid
fills the capsule that encloses the entire joint
Uniaxial joints
operate as hinges (like the elbow)
Biaxial joints
allow movement around to axes (wrists, ankles)
Multiaxial joints
allow movement about all three perpendicular axes (shoulder and hip)
vertebral column
made up of several vertebral bones separated by flexible disks that allow movement to occur
vertebrae groupings
cervical vertebrae, thoracic, lumbar, sacral, coccygeal
fleshly attachments
most often found at the proximal end of a muscle
Fibrous attachments
tendons, they blend into and are continuous with both muscle sheaths and the connective tissue surrounding the bone
agonist
the muscle most directly involved in bringing about a movement, AKA prime mover
antagonist
a muscle that can slow down or stop the movement
synergist
a muscle when it assists indirectly in a movement
lever
a rigid or semirigid body that, when subjected to a force whose line of action does not pass through its pivot point, exerts force on any object impeding its tendency to rotate
fulcrum
the pivot point of a lever
moment arm
the perpendicular distance from the line of action of force to the fulcrum
torque
the degree to which a force tends to rotate an object about a specified fulcrum. It is defined quantitatively as the magnitude of a force times the length of its moment arm
muscle force
force generated by biomechanics activity, or the stretching of non contractile tissue, that tends to draw the opposite ends of a muscle toward each other
resistive force
force generated by a source external to the body that acts contrary to muscle force
mechanical advantage
the ratio of the moment arm through which an applies force acts that through which a resistive force acts
first-class lever
a lever for which the muscle force and resistive force act on opposite sides of the fulcrum (
second-class lever
a lever for which the muscle force and resistive force act on the same side of the fulcrum, with the muscle force acting through a moment arm longer than that through which the restive force acts, (calf muscle to raise leg)
third-class lever
a lever for which the muscle force and resistive force act on the same side of the fulcrum, with the muscle force acting thought a moment arm shorter that that throughout which the resistive force acts
anatomical position
body erect, the arms are down at the sides, and the palms face forward
Three planes of the human body
Sagittal, frontal, and transverse planes
acceleration
change in velocity per unit time
strength
the maximal force that a muscle of muscle group can generate at a specified velocity
power
defined as “the time rate of doing work”
work
the product of the force exerted on an object and the distance the object moves in the direction in which the force is exerted
weight
the multiplication of the mass of the bar by the local acceleration of gravity
angular displacement
the angle through which an object rotates
angular velocity
the object’s rotational speed, measured in radians per second
rotational work
=torque x angular displacement
recruitment
getting motor units involved in muscle contraction
rate coding
the rate at which the motor units are fired
pennate muscle
fibers that align obliquely with the tendon, creating a featherlike arrangemtn
angle of pennation
the angle between the muscle fibers and an imaginary line between the muscle’s origin and insertion
concentric muscle action
a muscle action in which the muscle shortens because the contractile force is greater than the resistive force
eccentric muscle action
a muscle action in thick the muscle lengthens because the contractile force is less that the resistive force
isometric action
a muscle action in which the muscle length does not change because the contractile force is equal to the resistive force
classic formula
the load lifted is divided by body weight to the two-thirds power
inertial force
can act in any direction
bracketing technique
the athlete performs the sport movement with less than normal and greater than normal resistance
friction
the resistive force encountered when one attempts to move an object while it is pressed against another object
fluid resistance
the resistive force encountered by an object moving through a fluid
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 passing through it
lordotic
a normal, slightly arched back
kyphotic
slightly rounded, as the back is in its normal s shape
Valsalva maneuver
when the glottis is closed, thus keeping air from escaping the lungs, and the muscles of the abdomen and rib cage contract, creating rigid compartments of liquid in the lower torso and air in the upper torso
