Movement Science Final Exam: Biomechanics Intro

What are the 5 reasons why it is important to understand the biomechanics of human movement?

1) Choosing correct/best CP, SCP, DS, LOC

2) Assessment/Diagnosis

3) Understanding mechanism of injury

4) Help guide most appropriate and precise treatment

5) Understand how body moves, which results in better patient care & outcomes/prognosis

What is Newton's First Law of Motion?

(TQ)

Body remains at a state of rest or remains in uniform motion until a force acts on it

What is Newton's Second Law of Motion?

(TQ)

Acceleration of an object is directly proportional to the force causing motion and inversely proportional to the mass of the object being moved

F = ma

What is Newton's Third Law of Motion?

(TQ)

For every action there is an equal and opposite reaction

(Force always occurs in pairs)

Which Newton's Law is this an example of?:

Kick a soccer ball in a specific direction, we are exerting force on the ball. The harder we kick the more force we apply, and the further the ball goes.

Newton's Second Law

(Acceleration directly proportional to force & inversely proportional to mass; F = ma)

Which Newton's Law is this an example of?:

Car stops suddenly, the passengers still feel forward motion. This is due to the inertia of motion whereby the car begins to stop while the body inside is still in a state of motion

Newton's First Law

(Body remains at a state of rest or uniform motion until a force acts on it)

Which Newton's Law is this an example of?:

When you sit in a chair, you are constantly pushing on the chair with a downward force. The chair is also pushing you back with an upward force; otherwise, the chair would collapse and you would fall

Newton's Third Law

(Every action has an equal and opposite reaction)

Which Newton's Law is this an example of?:

When you turn off a table fan, the blades continue to move for some time even without electricity.

Newton's First Law

(Body remains at a state of rest or uniform motion until a force acts on it)

Which Newton's Law is this an example of?:

Birds flying. The wings of the bird push the air, creating an upward force which helps them move forward. This is also used with airplanes and helicopters.

Newton's Third Law

(Every action has an equal and opposite reaction)

Which Newton's Law is this an example of?:

In racing cars, engineers try to keep vehicle mass as low as possible. This means with lower mass more acceleration can be provided. If the acceleration is higher, the chances of winning the race are also increased

Newton's Second Law

(Acceleration directly proportional to force & inversely proportional to mass; F = ma)

Which Newton's Law is this an example of?:

A dirty dish lying on the table will not move or get cleaned unless you apply some force and put it in the dishwasher

Newton's First Law

(Body remains at a state of rest or uniform motion until a force acts on it)

Which Newton's Law is this an example of?:

Movement of an object is more difficult, especially for weak muscles. But once the object is moved, continued motion is easier to maintain.

Newton's First Law

(Body remains at a state of rest or uniform motion until a force acts on it)

Which Newton's Law is this an example of?:

While swimming or moving in a rowboat, when you push the water backward, there is an equal and opposite force generated which causes forward motion

Newton's Third Law

(Every action has an equal and opposite reaction)

Which Newton's Law is this an example of?:

During a car accident, the force between the car and the obstacle is known as impact force. This force depends on the masses of collision vehicles and the speed at which they are moving. This means that if a bigger and heavier vehicle moving with greater speed is involved in a collision, the intensity of the impact force will be greater

Newton's Second Law

(Acceleration directly proportional to force & inversely proportional to mass; F = ma)

What is the total movement of an object without regard to the direction (total distance covered)?

Distance

What is the straight line distance from Point A to Point B?

Displacement

What is how fast you're traveling?

Speed

(Ex: distance/time; m/s/ mph)

What is the speed in a given direction, including both rate and direction of an object movement, and is the time rate of change of displacement?

Velocity

(Ex: m/s forward; mph northeast)

What is the time rate of change of velocity (Vf - Vs / time)?

Acceleration

(Ex: m/s2)

What is negative acceleration? Why is it important in terms of injury?

Deceleration

- Crucial for lowering the risk of injury

What is the quantity of matter composing an object (compared weight which is a vector)?

Mass

Ex: g, kg

What is the quantity of motion an object possesses (tendency of a body to stay in motion)? What is the equation to calculate this?

Momentum

(Momentum = mass x velocity)

What is a form of energy that causes movement and has direction and magnitude? What is the equation to calculate this?

Force

Force = mass x acceleration

What is movement in a straight line? What is rotational movement through an arc?

(TQ)

Linear motion

Angular motion

Which type of motion occurs at the joints of the human body?

(TQ)

ALL joint movement is rotational/angular

What is the point in the body or an object around which its weight is balanced and equal on all sides?

Center of gravity

Where approximately is center of gravity located in the human body? Does it change location or does it always stay constant?

Anterior to 2nd sacral vertebra

(NOTE: slightly higher in men (L5) than women)

Center of mass moves as we move

What is the imaginary line that runs through the center of gravity?

Line of gravity

What is the area of contact between the body and the supporting surface?

Base of support

If the line of gravity falls within the base of support or falls outside the base of support, how does that impact stability?

Must fall within the base of support for object to be STABLE

- balanced is maintained when center of gravity remains over or within the base of support

T/F: The larger the base of support, the more stable and balanfced the object

TRUE

What are the 3 criteria that can increase the base of support?

1) Two points of contact

2) Widening points of contact

3) Larger surface area of ground contact

T/F: Force is always something that is externally applied

FALSE

- can be internal or external (usually produces either a push or pull)

What is the force exerted by the ground on a body in contact with it?

Ground reaction force

When accelerating, a ________ GFR will yield ________ power

When decelerating, a ________ GFR yields _______ forces on the body

Higher & Greater

Lower & Lower

What is describing a muscles relative ability to resist or produce force, and is the greatest measurable force that can be exerted by a muscle or group to overcome resistance during a single max effort?

Strength

Can we measure strength in terms of the human body for single muscles and/or movement patterns?

YES

What is the formula for calculating work?

Work = Force x Distance

W = F x D

If we're applying the same force over a longer distance, would that increase or decrease the work performed?

Increase work performed

What is the formula for Power?

Power = Work / Time

P = W / t

Power is developed by ____________ the amount of force and/or distance, or by _____________ the amount of time to complete.

Increasing

Decreasing

What is the capacity to do work?

(TQ)

Energy

Which of the two types of energy discussed is the capacity to do work that is stored in a body?

(TQ)

Potential energy

Which of the two types of energy discussed is the energy a body has because of its motion?

(TQ)

Kinetic energy

When a moving body stops, kinetic energy is all converted to what?

(TQ)

Potential energy

What is the law of conservation of energy?

(TQ)

Energy can neither be created nor destroyed. It is only changed from one form to another.

What is a force that changes the form or shape of a body?

(TQ)

Stress

What is the amount of change in the size or shape of the object caused by the stress?

(TQ)

Strain

What is Hooke's Law?

(TQ)

The relationship of stress and strain to elasticity

Strain (change) becomes ___________ to the stress (force) producing it as long as strain is not too great. Once the _________ limit is exceeded, permeant deformation occurs.

Proportional

Elastic limit

What is unaligned forces acting on one part of the body in a specific direction, and another part of the body in the opposite direction. Why is this important?

Shear force

Chiropractic adjustments!

What is the twisting of an object due to an applied torque?

Torsional force

What is the ability of an object to resist deformation (strain) when a stress is applied to it?

(TQ)

Stiffness

What is the ability of an object to resume its former shape after a deforming or distorting force is applied and then released, such as tendons?

(TQ)

Elasticity

How are stiffness and elasticity related?

(TQ)

They are at OPPOSITE ends of the spectrum

T/F: Some structures in the human body are a combination of stiffness and elasticity, while some are purely for stiffness or elasticity.

FALSE

ALL substances have some degree of elasticity (it's a combination; but some substances have more elasticity than others)

Looking at ligaments, tendons, and bones, what is their degree of elasticity in comparison to each other? Stiffness?

(TQ)

Elasticity:

Tendons > Ligaments > Bones

Stiffness = Opposite

Bones > Ligaments > Tendons

What is the idea that a material will be able to deform and return to its original shape, repeatedly without permanent deformation?

Elastic deformation

What is a loading force that causes permanent change in the structure of a material?

Plastic deformation

What limit must be crossed for plastic deformation to occur?

Elastic limit

What is Wolff's Law?

Bones will adapt to the loads under which it's placed

- if loading on a particular bone, bone will remodel itself over time to become stronger/resist that sort of loading

What is the major load-sharing/distributing tissue in the human body & MSK system that holds our cells and tissues together? What is the response of this tissue to mechanical loads?

Fascia

-- communicates & remodels in response to mechanical loads (ex: compression, tension, strain)

What occurs when a low-level stress, usually starting in the elastic range of a tissue, is applied over a long enough period to cause deformation of the tissue in its plastic range?

Creep

T/F: Creep is always a reversible phenomena

FALSE

Reversible unless you stretch material beyond elastic capacity/threshold

What role does creep play in postural dysfunction and tendon elasticity?

Poor posture over time causes changes in muscles/joints/connective tissue

-- permanent changes in tissue length over time with repetition of any position

What is the phenomenon in which the value of the physical property lags behind changes in the effect causing it?

Hysteresis

What is the point at which a tissue or object can no longer withstand a stress and breaks/fails?

Structural fatigue

How can structural fatigue occur?

Can occur in a sudden movement (ex: torn ligament) or over time w/ accumulation of stress (ex: rotator cuff tendinopathy/stress fracture)

T/F: All tissues and objects are subjected to structural fatigue

TRUE

What is the length between a joint axis and the line of force acting on that joint?

Moment arm (Lever arm; Resistance arm)

T/F: Every joint involved in exercise has a moment arm (Lever arm; Resistance arm)

TRUE

The longer the moment arm, the _____ torque, and the _____ force applied to the joint axis through leverage

More & More

What is the force casing rotational movement? What factors change this?

Torque

What two factors change torque?

Force & Length

What is the long axis of the muscle?

Line of pull

What is the angle between the long axis of the bone (moment arm) and the line of pull of the muscle? Why is this important?

Angle of pull

Important in therapeutic exercise

If you want to produce maximal torque, the joint must be positioned so that the muscle being worked has a ______ degree angle of pull on the extremity and the moment arm is at its ______ length

90 degree angle of pull

Moment arm at its GREATEST length

What impact does increasing/decreasing the angle of pull have on the rotational force of a joint? Non-rotational forces at the joint?

Rotational = DECREASES

Non-rotational = INCREASES

Nonrotational force will either _________ the joint by providing compression or it will _________ the joint by providing a distraction force depending on the _____________.

Stabilize

Destabilize

Angle of Pull

What is the correct order of resistance, force, and axis for a 1st class lever?

(TQ)

Fulcrum (axis) between the Force and Resistance arms

F - A - R

What are the 3 major characteristics of First class levers?

(TQ)

1) BALANCED movement

2) Axis CLOSE to resistance and force

3) Convert downward force to upward force

What is the correct order of resistance, force, and axis for a 2nd class lever?

(TQ)

Resistance lies between the Force and the Fulcrum (Axis)

A - R - F

What are the 3 major characteristics of a 2nd class lever?

(TQ)

1) Move LARGER resistance with little force

2) Load moves in SAME DIRECTION as force applied

3) Small ROM

What is the correct order of resistance, force, and axis for a 3rd class lever?

(TQ)

Force point is between the Resistance and the Fulcrum

A - F - R

First (1st) throw the stick F A R, then (2nd) your dog will A R F (like a bark) and run AFteR (A F R) the stick.

What are the 3 major characteristics of a 3rd class lever?

(TQ)

1) produces SPEED

2) more movement DISTALLY than near force

3) Increased ROM

What is the MC lever in the body?

(TQ)

3rd class lever

What lever includes examples such as wheelbarrow, nutcracker, stapler, pushups, or calf raises?

(TQ)

2nd class lever

What lever includes examples such as tongs, shoveling, catapult, baseball swing, elbow flexion, or knee flexion?

(TQ)

3rd class lever

What lever includes examples such as seesaw, scissors, crowbar, or cervical extension (OA joint)?

(TQ)

1st class lever

What is a characteristically physiologic advantage of muscles?

(TQ)

A muscles ability to SHORTEN

What is the optimal length of a muscle for maximal physiologic advantage, and is the extend to which a muscle can be lengthened to a relaxed condition without producing tension or any additional stretch?

Full resting length

When a muscle shortens or lengthens, its physiological advantage becomes progressively ______ until _______ to produce a force

LESS

UNABLE to produce a force

What type of muscles are prone to active and passive insufficiency?

Multi-joint muscles

What is the inability of a bi-articulate (two-joint) or multi-articulate (multi-joint) muscle to exert adequate tension to SHORTEN enough/sufficiently to complete a full range of motion in both joints simultaneously?

Active insufficiency

If a multi-joint muscle shortens as far as possible, it affects the __________ of all joints it crosses so that none of the joints can complete __________________, creating so much slack that muscle tension is almost completely _________.

Position

Full (shortening) ROM

Gone

What is the inability of a bi-articulate (two-joint) or multi-articulate (multi-joint) muscle to STRETCH enough/sufficiently to complete a full range of motion in both joints simultaneously?

Passive insufficiency

If a multi-joint muscle is stretched to its maximum length over the joints it crosses, it does not have enough ________ to allow all of the joints to reach their _____________

Length

End positions

Is this an example of active or passive insufficiency?:

Shortening of Rectus femoris limits hip flexion when knee fully extended

Active insufficiency

Is this an example of active or passive insufficiency?:

Maximal shoulder flexion cannot be achieved at the same time as maximal elbow flexion due to shortening of teh biceps brachii

Active insufficiency

Is this an example of active or passive insufficiency?:

Full knee flexion limited by stretching of rectus femoris if the hip is fully extended (many people cannot assume that posture because of quads passive insufficiency)

Passive insufficiency