Chapter 3 Biomechanics of Resistance Training Flashcards
Define anatomy and biomechanics.
Anatomy is the study of components that make up the musculoskeletal machine
Biomechanics is the mechanisms through which these components interact to create movement
What does the axial and appendicular skeletons consist of?
The axial skeleton consists of the skull (cranium) and vertebral column, ribs and sternum
The appendicular skeleton consists of the shoulder girdle, bones of the arms, wrists, and hands, pelvic girdle and bones of the legs, ankles, and feet
What are joints and what are the different types of joints?
Joints are junctions between bones.
Fibrous joints (sutures of skull) allow virtually no movements
Cartilaginous joints (intervertebral disks) allow limited movements
Synovial joints (elbow & knee) allow considerable movement
What are the different categories of joints?
Uniaxial (knee & elbow) joints operate as hinges. rotating about only 1 axis
Biaxial joints (ankle & wrist) allow movement about 2 perpendicular axes
Multi-axial joints (shoulder & hip) ball and socket joints that allow for movement in all 3 perpendicular axes
What are the 5 groups that make up the vertebral column?
7 cervical vertebrae 12 thoracic vertebrae 5 lumbar vertebrae 5 sacral vertebrae 3-5 coccygeal vertebrae
Define the origin and insertion of muscle.
Origin is the proximal attachment (toward the center of the body)
Insertion is the distal attachment (away from the center of the body)
Names the various ways muscles are attached to bone.
Fleshy attachments muscle fibers are directly attached to bone usually at the proximal end
Fibrous attachments (tendons) blend into & are continuous with both the muscle sheath and the connective tissue surrounding the bone
Name and define the action of muscle.
Agonist - prime mover
Antagonist - muscle that slow down or stop the movements
Syngerist - assists indirectly in a movement
Define level and fulcrum.
Lever - a body that exerts force on any object impeding its tendency to rotate
Fulcrum - the pivot point of a lever
Define moment arm and torque.
Moment arm - the perpendicular distance between the line of force and the fulcrum
Torque - the force of rotating an object about a fulcrum. Force x length (moment arm)
Define muscle force and resistive force.
Muscle force - force generated by an activity that tends to draw the opposite ends of a muscle toward each other
Resistive force - force generated by a source external to the body (gravity, inertia, friction) that acts contrary to muscle force
Describe mechanical advantage.
A situation in which the moment arm of the muscle force is greater than the moment arm of the resistive force and is therefore more than 1.0.
A mechanical disadvantage exists when the moment arm of the muscle force is less than the moment arm of the resistive force and is therefore less than 1.0.
Name and describe 3 types of levers.
First class levers - the fulcrum is between the muscle force and resistive force (elbow extension)
Second class levers - the fulcrum and the muscle force is at opposite ends and the resistive force is in the middle (calf raiser)
Third class levers - the fulcrum and the resistive force are at opposite ends and the muscle force is in the middle (bicep curl)
What are the advantages/disadvantages in having tendon insertion farther away from the fulcrum? Why?
when the tendon insertion is farther away from the joint center, the muscle force acts through a longer moment arm and thus can produce greater torque around the joint (lift more weight)
there is a loss of maximum speed because the muscle has to contract more to make the joint move through a given ROM.
Define acceleration.
the change in velocity per unit of time
What is Newton’s second law?
Force = mass x acceleration
What is Knuttgen and Kraemer’s definition of strength?
strength - the maximal force that a muscle or muscle group can generate at a specified velocity.
What is the (scientific) definition of of work and power?
work = force (exerted on the object) x distance (the object moves)
power = work / time (the rate of doing work)
What are the SI units for force, distance, work, and power?
force - newtons
distance - meters
work - joules (newton-meters)
power - watts (J/s)
How would you measure vertical travel of free weight exercises vs. weight-stack exercise to quantify the volume of a workout?
vertical travel (weight exercise) = height of the bar relative to the floor - height of the bar at its highest position
vertical travel (machine) = height of stack at lowest weight plate - highest position of lowest weight plate
What is angular displacement and what is its SI units?
the angle at which an object rotates.
radian = 180 degrees / (pie) = 57.3 degrees
What is angular velocity and what is its SI units?
an object’s rotational speed
radians/second (rad/s)
What is the difference between torque and work?
torque (distance component) = the length of the moment arm
work (distance component) = the distance moved along the line of action of the force
What is the difference between strength and power?
strength is the capacity to exert force at any given speed
power is the mathematical product of force and velocity at whatever speed
How does neural control affect the maximal force output of a muscle?
By determining which and how many motor units are involved in a muscle contraction (recruitment) and the rate at which the motor units are fired (rate coding)
What is improvement in strength among the 1st few weeks attributed to?
Neural adaptations
What is the force a muscle can exert related to?
The cross-sectional are rather than its volume- strength training increases both the strength and cross-sectional area of muscle
What is one arrangement and alignments of sarcomeres in relation to the long axis of the muscle?
Pennate muscle - fibers align obliquely with the tendon creating a feather-like arrangement.
Define the angle of pennation.
The angle between the muscle fibers and an imaginary line between the muscle’s origin and insertion
What are the advantages and disadvantages of pennate muscle?
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How does muscle length affect force output?
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In what way does the amount of torque that can be exerted about a given joint vary through the joint’s ROM?
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What is the relationship between the force capability of muscle and the velocity at which it contracts?
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What improves the force-velocity relationship?
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Describe the 3 types of muscle actions.
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How does muscle torque vary with joint angular velocity according to type of muscular action?
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What does the strength-to-mass ratio reflect?
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When body size increase what increases proportionately? Why is this a disadvantage?
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What is the classic formula for comparing loads lifted for different weight classes?
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What is the difference between mass and weight of an object?
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What is the equation for an object’s weight (force)?
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What is the relationship between weight and torque?
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What is the resistive torque pattern of a squat when the trunk is inclined forward? When the bar is positioned lower on the upper back?
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