KIN 3514 Midterm

True or false? Athletes have to fit in perfectly into a given category (sports athletes cannot have combinations of traits in all 3 categories)

False

Osteoporosis

When resorption exceeds deposition (bone density is reduced and bone structure is weakened (lower bone stiffness) - increases risk of fracture - related to hormonal factors (decrease estrogen, bones weak) - nutritional imbalances - lack of exercise

Can an object accelerate with no velocity?

Yes

Oblique plane

a plane that is any type of angle other than horizontal or vertical angle

complex kinetic chain

a segment is linked to more than two other segments (ex- the torso)

tibiofemoral structure

anatomical axis, q-angle

Pennation angle

angle made between muscle fibers and line of pull of the muscle

acetabular anteversion

angle of that orientation is more forward, (male range: 8 degrees, female range: 14 degrees), increased angulation is associated with reduced joint stability and early onset of osteoarthritis

force arrows

are labeled according to type, point in direction of the force, havea length that is in proportion to their relative strength (longer arrows = stronger forces)

zone of weakness

area in the femoral neck that has fewer trabecular fibers crossing

Parallel/Fusiform muscle fibers

arranged along the long axis of a muscle, allow for greater range of shortening and greater shortening velocities, often used for fast and extensive movements. normally long muscles which cause long movements, not very strong but have good endurance

Pennate muscle fibers

arrangements diagonal to the longitudinal axis of the muscle; more fibers present in a given muscle, greater force production, but slower movements and smaller range of motion

power-velocity relationship

as power increases, force decreases (takes less force because you have more power)

Sarcomere Force-length relationship

myosin pulls on actin to bring actin closer to the midline during concentric and opposite during eccentric

OSteopenia

natural age-dependent loss of bone density; begins between ages 30-40; women lose 8% bone. mass per decade, men lse 3%); the epiphyses, vertebrae, and jaw are most affected; results in fragile limbs, reduction in height, tooth loss

midfoot

navicular, 3 cuneiforms, cuboid (function: assist in the formation of the transverse arch, assist in forming a midfoot lever to transmit forces from the hindfoot to the forefoot)

plastic region

no longer linear, even after the load is removed deformations are not reversed, if the applied force continues past the plastic region, the tissue will eventually fail

isometric contraction

no movement, length of sarcomeres does not change

linear strain

occurs as a result of a change in the object's length

shear strain (gamma)

occurs as a result of a change in the orientation of the object's molecules

eversion

occurs when the lateral side of the sole of the foot is lifted

Rotation

occurs when the system is restricted to move around a fixed axis- therefore in a circular path, also called angular motion

torsion stress

occurs when torques act about the long axis of the object at each end. (internal resistance to twisting)

hip-bone structure

trabecular system, zone of weakness

elastic modulus (Young's modulus)

- Stiffness of a material (ratio of stress to strain) - Good predictor of materials ability to resist bending or change in shape - Important property for dental bridges, orthodontic wires

Steps to draw a FBD

1) isolate object of interest 2) pick a point at the center of the object 3) identify forces on an object 4) draw in forces as vectors 5) draw in coordinate axes

foot structures

28 bones, 2 sesamoid bones and 27 articulation, >100 ligaments hindfoot, midfoot, calcaneus

medial meniscus is __ time as thick as the lateral meniscus

3

tendon and ligament composition

70% water, 25% collagen

Ellipsoid joint

Allows movement in 2 planes (flexion/extension, abduction/adduction), can be found in wrists and fingers

q-angle

Angle formed by drawing a line from the center of the patella to the anterior superior iliac spine, and from the tibial tubercle through the center of the patella; men average a 14-degree angle whereas women average about 17 degrees.

Somatotype

Another word for body type; a way of describing a body build

Since the form of the body directly affects sport performance,

Athletes have different body characteristics depending on the type of sport

Effects of Aging on Bones

Bones become thinner and weaker with age

Vectors

Can be used to describe forces in free-body diagrams; direction and magnitude

Hooke's Law

F=kx (When x is 0 or smaller, no cross bridge will attach in this region)

stress (sigma)

Internal resistance to deformation, not measures as just a force, but a force acting over a unit cross-sectional area of material

Photoscopic Method

Method of assessing somatotypes: William Sheldon, 4000 pictures of young people

Anthropometric Method

Method of assessing somatotypes: rating form, body dimensions. (height, weight, skinfold thickness, width, girth)=

Joints

Parts of the body where two or more bones meet to allow movement

What is the plane of motion for most of the joint actions that occur during sprint running? What is the corresponding axis for motion for these joint actions?

Sagittal plane and transverse axis

Which mechanical stress cause the most bone injuries?

Shear stress (ex- in football, a striker can be tackled back and forth by opponents)

Hinge joint

Simple joint, 1 DOF (flexion and extension); approximate a round cylinder that fits into a matching shallow trough

Wolff's Law

States that most tissues in a healthy person or animal will adapt to loads placed upon it

Sarcomeres

Thin filaments in a hexagonal array around the thick filaments (myosin), each thin filament (actin filament) can form "cross-bridges" with thick filaments

Limitation of BMI

This is an inaccurate measure of body fat content and does not take into account body composition (muscle mass, bone density, etc.)

Structure of the hip joint

acetabulum is normally directed laterally, anteriorly, and inferiorly

What joint action occurs at the shoulder joint and what are the plane and axis of motion during the pulling up phase of a wide-grip pull up?

adduction in frontal plane around the anteroposterior axis

Saddle joint

allows 2 planes of movement (flexion/ extension, ad/abduction). forun in carpometacarpal joint of the thumb

ball and socket joint

allows movement in 3 planes and is the most mobile of the synovial joints (flexion/extension, ab/adduction, rotation)

Abduction

along frontal plane, around anteroposterior axes, causes limb movements in frontal planes through the largest range of motion (away from the body)

Adduction

along frontal, around anteroposterior, causes limb movement back toward the anatomical position

lateral flexion

along frontal, around anteroposterior, occurs at trunk and neck

Pivot joint

also allow movement in one plane 1 DOF, (rotation, pronation, and supination): approximate a pin inserted into a hole or a cylinder that fits into a shallow trough

knee joint function

alters the length of the lower extremity, locomotion

Kinetic chain

an engineering concept used to describe human movement; each segment of the body is considered a rigid link system

bone is strongest where fibers are

at a 90 degree angle

inversion

at the ankle joint, occurs when the medial side of the sole of the foot is lifted

hip joint- articulating surface

ball and socket joint, acetabulum (pelvis side), femoral head

anisotropic characteristics

behavior of bone varies with the direction of the force applied (ex- bones are strongest in compression and weakest in shear)

Viscoelastic Characteristics

bone adapts differently depending on loading rates and duration; able to absorb more energy at faster rates of loading

epiphyseal cartilage

cartilage ends of long bones ossify soon after birth, except for the cartilage that separates from the rest of the bone. This cartilage eventually disappears (long bone stops growing in length between ages of 10-25)

Endochondral ossification

cartilage is replaced by bone

linear strain (epsilon)

change in length/ original length

General motion

combination of linear and angular motion (most human motion)

which mechanical stresses occur most frequently during daily activities?

compression- but injuries from pure compressive stress are uncommon

Advanced methods of anthropometry

computerized tomography (CT), magnetic resonance imaging (MRI), ultrasound, DEXA, 3D body scanner

wihout meniscus:

contact area is reduced by 50% (stress = force / area). the load ont he femoral condyle is doubled, toad on tibial condyles may increase 6-7 times, friction increases by 20%

hyaline cartilage

cover articulation ends of bone, consists of 60-80% H2O and a matrix of collagen and proteoglycan; has anisotropic and viscoelastic characteristics, has low coefficient of friction allowing movement between bones smoothly. functions: absorb shock and provide an extremely smooth surface to make movement easier, transmit the compressive loads from bone to bone joints

Ergonomics

create safe machinery and protective equipment using anthropometry

frontal (coronal)

divides into front and back sections (anterior and posterior); allows for side to side movements

Sagittal (side)

divides into right and left sections (or lateral both ways); split through middle

transverse (horizontal)

divides into upper or lower sections (superior or inferior); allows for spinning motion like throwing a frisbee

pronation of the foot

dorsiflexion at the ankle(sagittal), eversion in the tarsals(frontal), abduction of the forefoot(transverse)

simple kinetic chain

each segment participates in no more than two linkages (ex- the arm)

cartilage types

elastic, fibrous, hyaline

large q-angle in landing from a jump or cutting maneuver

excessive hip adduction and internal rotation during weight bearing have the potential to affect the kinetics/kinematics of the entire lower extremity. This is an indicator of potential injury including ACL tears and patellofemoral pain

Isokinetic movement

exercise refers to. movement at a constant speed regardless of the force applied; measures the power produced by maximal effort knee extension.flexion at varying velocities of contraction

hyperextension

extension is continued to the point that beyond the anatomical position

elastic cartilage

external ear, several other organs, maintains shape

a large q-angle is always a biomechanical factor that can increase injury risk

false

compression is the most common. examples:

femur and tibia are under compression, as a result of your body weight pushing down on the proximal end and the reaction force from below pushing up on the distal end. During a push up, forces push up on each end of the humerus, and it is axially loaded in compression

structure of the knee joint

femur, patella, medial collateral ligament, lateral collateral ligament, anterior cruciate ligament (ACL), lateral meniscus, medial meniscus, fibula, tibia

Range of motion examples

flexion/extension, pronation/supination, radial and ulnar deviation

shear stress (tau)

force / cross-sectional area at the analysis plane

force-velocity relationship

force decreases as velocity increases

abduction of the leg at the hip (side leg raise) is movement in the ___ plane around the ___ axis

frontal, anteroposterior

abduction of the arm at the shoulder is the movement in the ___ plane in the ___ axis

frontal, anterposterior

tendon and ligament function

guide normal movement and restrict abnormal movement, maintain joint congruence, sending joint loading/strains

ulnar deviation

hand movement in a frontal plane toward the little finger

radial deviation

hand movement in a frontal plane toward the thumb

flat bones

have flat surfaces and are thinner in one dimension; designed for protection and provides a large surface for muscle attachment (ex- skull, scapula, ilium, sacrum)

Endomorph

high body fat, soft body, round shoulders, wide hips, slim wrists, and ankles

When you swing a baseball bat, what is the plane of motion for the action occurring at your leading shoulder? What is the axis of motion? What joint action occurs at the leading shoulder during the swing?

horizontal abduction (lateral rotation) in transverse plane around longitudinal axis

bending

in general, multiple stresses occur in an object or human body, and this creates complex patterns, like bending stress, creates both compression and tension stresses

meniscus reduces

incongruency

meniscus function

increase joint stability, shock absorption, reduce friction, distribute force, surface area --> reduce stress (force/area)

Large cross-sectional area

indicates more sarcomeres are contributing to contractile force

depression

inferior movement of the scapula

fibrous cartilage

intervertebral discs, resists compression, shock absorption, reduced friction between bony surfaces very tough and strong tissue, predominantly found in the intervertebral disks, pubic symphysis, or meniscus; can withstand a high load; also forms to improve fit between bones

internal rotation

inward or medial rotation along transverse plane around longitudinal axes

function of joints

join bones together while controlling the motion allowed between them; transfer between bones and joints

functional classification of joints

joints are classified according to how much they. move (ex- skull, pubic bones in pelvis dont move at all)

ligament fiber arrangement

larger elastic components and this always makes them less stiff and slightly weaker than tendons

knee joint

largest joint, consist of: tibiofemoral joint patellofemoral joint

Ectomorph

little body fat and muscle, narrow shoulders and hips, thin, flat chest

Mesomorph

low body fat, muscular body, broad shoulders, narrow hips, strong forearms and thighs

elastic region

low strain values, linear, fully reversed when the load is removed

Body Mass Index (BMI)

mass of body over height in meters squared

Dynamic measures

measurements are taken while the body is engaged in some physical activity (functional anthropometric data)

medial or lateral meniscus accepts more load

medial

forefoot

metatarsals, phalanges, medial and lateral sesamoid (function: adapts to uneven surfaces, assist in balance and dynamic control)

Translation (linear)

motion along one of the x,y, or z axes in which all points of the system move at the same time, in the same directions, and the same distance with respect to the defined reference frame, also called linear motion

horizontal abduction (horizontal extension)

move away from the midline of the body; does not commence from anatomical position (starts with arms straight in front)

synovial joints

moveable joints; most common type of joint in the body - low friction articulation - can withstand significant wear and tear and provide shock absorption

flexion

movement around transverse axis that decreases the angle of a joint

extension

movement around transverse axis that increases the angle of a joint

plane or gliding joint

movement is "nonaxial" and no rotation takes place; found in carpls (had) and tarsals (foot)

abduction of shoulder

movement of scapula away from the midline (rounding back)

adduction of shoulder

movement of scapula toward the midline (pinching shoulder blades)

horizontal adduction (horizontal flexion)

movement toward the midline of the body; does not commence from anatomical position (starts with arms straight in front)

external rotation

outward or lateral rotation along transverse plane around longitudinal axes

Static measures

passive measures of the dimensions of the human body while in a fixed position (more easily determined)

structure of the hip complex

pelvic girdle and hip joint (articulating surface)

supination of the foot

plantar flexion at the ankle, inversion in the tarsals, adduction of the forefoot

concentric contraction

sarcomere shortens

trabecular system

present in the head and neck of femur, resist compressive stress that occurs on the femur

Functions of muscle

produce movement, maintain postures, stabilize joints (ex- isometric contraction, generate force without filaments shortening) - non-movement related: support and protect organs, maintenance of body temperature, control entrances and exits of the body

parallel arrangement

provide stiffness and has high resistance to tensile stress, but has little resistance to compression and shear

ankle/foot joint function

provides a stable base while conforming to UNEVEN surfaces (pronation, supination), shock absorbs through foot flexibility (pronate when feet hit the ground), transmits rotational forces into forward progression (like propulsive force)

anatomical axis

relationship between femoral and tibial axes gives slight valgus angle

deposition

response to increased stress (increase load, bones become stronger), due to weight bearing exercise; osteoblasts dominate

pronation

rotating the forearm so that palm is faced down and forearm is flexed; along transverse and around longitudinal

supination

rotating the forearm so that the palm face up; along transverse and around longitudinal

anteroposterior axis

running from anterior to posterior (perpendicular to frontal plane)

transverse axis

running from left to right (perpendicular to sagittal plane)

longitudinal axis

running from top to bottom (perpendicular to transverse plane)

What plane does your forearm lie in throughout the movement?

sagittal plane

flexion of the arm at the shoulder is movement in the ___ plane around the ___ axis

sagittal, transverse

flexion of the leg at the hip is movement in the ___ plane around the ___ axis

sagittal; transverse

eccentric contraction

sarcomere lengthens

synovial membrane

secretes synovial fluid into the joint to lubricate, reduce friction, and provide nutrition (main source of bone nutrition)

creep (strain) and stress relaxation effect

shows how cartilage is damaged under pressure initial period: strain increases, rapid fluid exudation increases and secretes synovial fluid, exudation stop: deformation stop, stress relaxation: deformation reduced If force continues to by applied, strain will be increased significantly and cartilage will be damaged.

Sliding filament and cross-sectional theory

skeletal muscles contract by sliding of actin filaments upon myosin filaments

short bones

small, solid, and block-like; hand and foot bones (the carpals and tarsals); important in shock absorption and transmission of forces

large pennation angles result in

smaller force being transmitted to the tendon, but greater physiological cross-sectional area)

sesamoid bones

special type of short bone, circular; provides attachment points (egx- patella)

Anthropometric Method equipment

stadiometer, weighing scale, skinfold caliper, sliding caliper, measuring tape

tendon fiber arrangement

stiffer and has high resistance to tensile stress

shear (transverse) stress (tau)

stress that resists sliding movement of parallel layers of material relative to each other ( internal resistance to prevent sliding of layers of object) (f/a)

kinetics

study of force- what's pushing/pulling

Antrhopometry

study of measurement (quantitative) of the human body used to study differences between race, age, and sex

kinematics

study of the spatial and temporal characteristics of motion; does not consider forces that lead to the observed motion

elevation

superior movement of the scapula

examples of bending

supports (heel and metatarsophalangeal joints), load (tibia, talus) compressive stress (bone of the foot), tension stress (plantar fascia, dorsal muscles)

Hip joint function

supports the weight of the head, arms, and trunk; stabilizes by controlling the alignment of the leg and provides great ROM, force transmission, locomotion

hindfoot

talus and calcaneus (function: initial foot contact, the progress into the midfoot and forefoot through loading response)

What are articular connective tissues?

tendons (muscle to bone), ligaments (bone to bone) they are passive structures (we don't have voluntary control of them)

when a compressive force is applied to cartilage,

tensile stress increases near the outer surface of the cartilage. the tensile strength of collagen holds the cartilage together under compressive loads because the collagen fibers are arranged near the exterior surfaces of the cartilage

Irregular bones

termed due to shape and provide for a variety of functions (support, distribute loads, protect spinal cord, muscle attachment)

speed

the distance traveled divided by the time it took to travel the distance (distance/time) "how fast an object is moving"

articular cartilage can withstand high compressive and tensile force, mainly because of

the fluid inside the collagen fibers

Eccentric force is greater than concentric force because

the proportion of cross-bridge is greater in the eccentric (rate of cross-bridge detachments (g) is decreased)

strain

the quantification of the deformation of a material (when objects are subjected to external forces, they deform)

velocity

the rate of change of displacement (displacement/time) "the rate at which an object changes its position"

acceleration

the rate of change of velocity (change in velocity/time)

multiplanar joint movement

the structure/geometry of most joints allows movement in multiple planes simultaneously

Newtonian anthropometry

this data is used in mechanical analysis of the loads on the human body; related to strength measures (Ex- grip strength and comfort)

anatomical reference axis

three reference axes for describing human motion (each is perpendicular to one of the three planes of motion)

ankle structure

tibiotalar joint (hinge joint: 1 DOF, articulations include proximal tibia/fibular, and distal talus)

ACL: failure

toe regions, linear (elastic region), plastic region, failure

plantar flexion

toes and foot toward the sole. occurs only at the ankle joint (along sagittal plane)

the total area under the stress-strain curve is a measure of

toughness

What axis is perpendicular to a sagittal plane?

transverse axis

rotation of the torso at the lumbar spine (trunk twist) is movement in the ___ plane around the ___ axis.

transverse, longitudinal

with the arms extended at the side at shoulder height, and bringing them forward and out, is movement in the ___ plane around the ___ axis

transverse, longitudinal

static q-angle doesn't really tell you much about the person's strength or biochemical perspective

true

True or false? Bone is stronger if a load is applied quickly, but weaker if a load is applied slowly

true (ex- slow loads can cause bone fractures, and fast loads cause ligament ruptures)

in what sports situations does tension stress occur?

tug of war, hanging by a bar in gymnastics

pelvic girdle

two coxa (or innominate bones), pubic symphysis - amphiarthrodial joint (not freely moveable)

Plane

two dimensional surface with an orientation defined by the spatial coordinates of three discrete points not all contained on the same line (imaginary flat surface)

resorption

type of bone remodeling; response to decreased stress (decrease load, bone becomes weak) due to disuse, immobilization, microgravity; osteoclasts dominate

dorsiflexion

upward flexion of the foot (along sagittal plane)

Forensics and criminolgy

use anthropometry as a form of identity analysis through skeletal measurements to determine biologic facts

epiphyseal lines

what epiphyseal plates grow into, visible on x rays

compression stress

when an object is axially loaded in compression, the object tends to deform by shortening in the direction of these external forces (internal resistance to shortening)

tension stress

when an object is axially loaded in tension (pull), the object tends to deform by stretching or elongating in the direction of the external loads. (ex- hang from a chin-up bar, the humerus is loaded axially in tension) (internal resistance to elongating)