BIOMECHANICS TEST 3

Active tension

active tension is greatest when the muscle is at its resting length, active tension decreases as muscle length goes above or below resting length

receptors

afferent or sensory organs that receive stimuli (receptors receive a stimuli)

Collagen turnover rate in tendons and ligaments

average of 300 to 500 days several months may be required to adapt, rebuild, or repair

fulcrum

axis of rotation (center)

leg extension

bad on the knees and the ACL, wear on the articular cartilage on the upper facet of the posterior surface of the patella

distress

bad stress- produces negative results

Reflex

comes from latin word meaning "to reflect" physical actions resulting form specific stimuli don't involve conscious activity if it requires any thought or analysis it is not a reflex it is a = conditioned response(pavlovian response)

Tm > Tr

concentric contraction- muscle shortens

photoreceptors

detect light

thermoreceptors

detect temperature changes

Proprioceptive neuromuscular facilitation PNF

involves alternately tensing and then relaxing and stretching targeted muscles - designed to maximize the use of the golgi tendon organs to improve flexibility

factors affecting range of motion

joint configuration- shape of the actual skeletal structure can affect the limits of the range of motion

Length Tension relationship

maximum potential isometric force is partly dependent on muscle length

Irritability

responding to a stimulus

Antagonists

slow down or resist movement caused by agonists or an external force by means of eccentric contraction

angle of pennation

the angle between pennate muscle fibers and the long axis of the tendon

first class levers

the applied force and the resistance are on opposite sides of the fulcrum- can favor the force or resistance depending on placement of fulcrum

third class levers

the applied force is between the resistance and the fulcrum- favors the resistance arm

resistance

the body begins to change to accommodate stress, important for being able to withstand stress for an extended period of time

Types of stress

the body has the same response however distress tends to produce more damage

alarm reaction

the body's first response to stress, produces the flight or fight response, cannot be sustained for very long

multipenniform

the fibers converge from several tendons (ex: tricpes brachii)

Pennate muscle fiber configuration

the fibers lie at non-parallel angle to the tendons long axis. the tendon tends to run along the full length of the muscle- a much larger number of cells in a given cross sectional area- they rotate about their tendon attachment or attachments, progressively increasing their angle relative to the tendonmuslce

penniform

the muscle fibers lie along one side of the tendon (ex: semimembranosus)

fracture healing in bone

unlike others bone heals by regeneration or replacement with the same type of tissue - NO SCAR FORMATION, original biomechanical properties may be regained

GES (galvanic electrical stimulation)

used for de-nervated muscle tissue (neural pathway is not intact), produces weak sustained or tetanic contractile force

IES (interferential electrical stimulation)

used for deep muscle stimulation,usually used for de-nervated muscle tissue, may be used where FES would have to raised to a painful frequency level to be effective

FES (faradic electrical stimulation)

used for innervated muscle (neural pathway is intact), can produce muscle contraction which may become tetanic

Ballistic (bounce) stretching

uses momentum of body movement to move a joint beyond the normal range of motion

law of conservation of energy

when gravity is the only external influence on an object, its mechanical energy remains constant

functions of the arches

when weight is placed on the foot the arch spreads out, stretching the elastic structure of the foot and storing the energy used to stretch them, as weight shifts towards the toes during walking, these elastic structures return to shape, giving up the stored energy- this energy is used to propel the body forward

Fascia

white fibrous connective tissue surrounding entire muscles and making up the structure of the perimysium and epimysium

acclimatization

whole body adaptation to adverse climate conditions such as heat, cold, high altitude, etc

intermittent tensile load exceeding the OSE

will cause an increase in the cross sectional area of the tissue (hypertrophy) as it works to regain an optimal strain environment

continuous tensile load exceeding the OSE

will result in creep or slow stretching of these tissues

exercise and bone health

wolffs law- bone remodels according to functional demand exercise promotes growth and development of bone tissue BONE IS MOST RESPONSIVE TO WEIGHT BEARING STRESS

combination of static equilibrium and controlled instability

wrestlers, gymnasts, and dancers

Passive tension

(produced by the parallel elastic component or PEC and series elastic component or SEC) increases as the muscle is stretched beyond its resting length

two basic mechanisms for hyperplasia

- large cells split into two or more cells (fission or mitosis) - new cells are formed from the precursors of mature cells (de novo formation)

characteristics of muscle fatigue

- reduction in muscle force capability -reduced shortening velocity - increase in the relaxation time of motor units between recruitment - with high intensity muscle activity over time the length of time a fiber stays contracted (twitch duration) increases

biomechanics of weight lifting basic factors

- relative torque muscle vs resistance - exercise variations to target specific muscles - anatomical considerations

static stretching

moving slowly into a stretched position and holding for an extended period of time usually 10-30 sec - allows the golgi tendon organs to override the effect of the muscle spindles or stretch reflex

Specific tissues

muscle bone ligaments and tendons cartilage

Hypertrophy

muscle fiber growth by increasing diameter through resistance training

bone tissue

support the body shape and structure protect internal organs provide mechanical frame for movement

full wave rectification

takes an AC signal and converts the negative values to positive. this allows for analysis of the absolute values of the signal

Extensibility

the ability to be stretched

balance

the ability to control equilibrium

sensory transduction

the ability to detect and translate a stimulus

Muscular endurance

the ability to exert muscle tension over a period of time, this may involve a continuous exertion as in an extended isometric exercise or a series of repeated movements as in rowing, running, cycling

Contractility

the ability to produce tension (muscle generates force by contraction)

Power

the amount of work performed over a given period time

Enegy

the capacity to do work

Negative work

the direction of muscle force is opposite the direction of movement. A eccentric contraction exist

Positive work

the direction of the muscle force is the same as the direction of movement. A concentric contraction exist

moment arm

the distance from any force or weight that produces torque to the fulcrum

muscles and tendons (active tissue)

the elasticity in muscle tissue adds a certain level of stability that isnt present with ligaments alone- improving strength in muscles can partially compensate for loss of joint stability

Potential energy

the energy of position , increasing the objects height increases its PE

Parallel muscle fiber configuration

the fibers or fasciculi are parallel to the tendons long axis (ex: soleus)- produce a faster rate of contraction in the entire muscle- the muscle shortens as a direct relationship of the shortening of the muscle fibers

mechanical advantage

the is the effectiveness of a lever at moving a resistance MA= force arm / resistance arm

Electromechanical delay

the lapse in time bw electrical activation of a muscle and the development of tension, believed to be the time required to stretch the SEC, therefore removing laxity from the muscle - shorter EMD is related to higher percentage of fast twitch fibers - higher contraction forces are associated with shorter EMD's

bipenniform

the muscle fibers lie on both sides of the tendon (Ex: rectus femoris)

Absolute muscle fatigue

the muscle is unable to develop tension when stimulated, the motor neuron may be unable to generate an action potential

afferent neurons

the neural pathways from the receptors to the central nervous system

Stretch shortening cycle

the pattern of eccentric contraction followed by concentric contraction- promotes storage and use of elastic energy (jumping,running)

Muscular power

the product of muscle force Fm and the velocity of muscle shortening- maximum power occurs at approx 1/3 of maximum velocity and 1/3 of maximum concentric force

Muscle power is more generally defined as

the rate of torque production at a joint or the product of the net torque and the angular velocity at the joint, therefore muscular power is affected by both strength and speed of the movement

what is the ratio for peak power production?

the ratio of type IIb, IIa and I for mean peak power production is about 10:5:1

second class levers

the resistance is between the applied force and the fulcrum- favors the force arm

root mean square RMS

the root mean square is taken of the set of peak values for the rectified voltage signal

terminal velocity

the state in which drag force equals the weight of an object- at terminal velocity the acceleration is 0

static equilibrium

the sum of all forces on all 3 axes equal = 0 sum of all torques = 0 for a static (isometric contraction) the torque produced by the muscle is equal in magnitude to the torque produced by the resistance Tm= Tr

sensory receptors

the system or organs which receive specific stimuli

Muscular tension

the tension produced by the muscle itself is directly related to the cross sectional area of the muscle and the condition or trained state of the muscle, long term training can increase the size and total force output potential of a muscle

Skeletal muscle fibers are classified based on what?

the time it takes to reach maximum tension

muscle torque

the torque or tendency to rotate at a joint produced by muscle action or muscle force

resistance torque

the torque or tendency to rotate at a joint produced by resistance or weight

principle of work and energy

the work produced by a force is equal to the change in energy that it produces in an object on which it acts

optimal strain environment OSE

this is the state of applied stress which a tissue is designed to accommodate. load/time

Electromechanical delay continued

muscle length, type of contraction (concentric, eccentric, etc) velocity of contraction, and fatigue don't seem to affect EMD, it may take a full second for a muscle to develop maximum isometric tension following EMD, EMD in children is significantly longer than in adults

Agonist Muscle

muscle which produce movement by concentric contraction- primary and secondary mover

surrounding active tissue (muscles and tendons)

muscles can restrict movement at joints as well as create movement- muscles can be greatly altered to change the ROM with out being permanently damaged

Muscular strength

muscles produce movement by generating torque at joints, muscular strength is actually based on the ability of a group of muscles to produce torque at a specific joint, Fm- force produced by muscle Dfa- distance of the force arm angle of pull

Examples of strain energy

muscles when they are stretched, the soles of shoes, vaulting poles, trampolines, etc

Muscular endurance is usually measured as?

muscular endurance is usually measured as resistance to muscle fatigue that is the more rapidly a muscle fatigues the less endurance it has- mechanism of fatigue may be muscle-specific or exercise-duration specific

satellite cells

myogenic stem cells can produce hypertrophy or hyperplasia

cutaneous skin receptors

near the skin surface- these receptors provide information about light touch and LOW frequency vibrations - meissner corpuscles - merkel discs - ruffini corpuscles

Motor Neurons

nerve cells that transmit a stimulus to muscle tissue

efferent neurons

nerves that transmit the reflex response (motor, secretory, or secreto- motor)

interneurons or internuncial neuron

neural connections between the afferent and efferent neurons. found in the spinal cord or brainstem

Agenesis

not created EX: plantaris muscle, palmaris longus

air drag is a force that is dependent on:

objects weight objects cross sectional area texture or roughness of the surface exposed to air

Active Insufficiency

occurs when multijoint muscles cant contract enough to produce a full range of motion at all joints crossed. (Ex: when the knee is in a state of flexion (as in seated calf raises), the gastrocnemius produces little or no force in plantar flexion because of slack in the muscle

Passive Insufficiency

occurs when tension in a multijoint muscle reduces the range of motion in the opposite direction. (Ex: flexion of the wrist will tend to put tension in the muscles that extend the fingers. therefore, its difficult to flex the finger when the wrist is flexed because of this tension)

factors affecting stability

- resistance to movement an objects mass ( Increase mass = increase stability) friction (greater friction = increase stability) fluid drag - balance height of c-g (lower c-g = greater stability) position of c-g relative to the edge of the base of support (greater horizontal distance = greater stability) base support (wider base = greater stability)

tendons and ligaments

- tendons transmit force from muscle to bone - most ligaments bind bones together or help maintain the position or structure of some of the body components - all tendons and ligaments are inelastic composed of bundles of collagen fibers surrounded by tissue that contains blood vessels and nerves

Factors affecting tissue adaptation

- type of stress - intensity of the stress - frequency - individual limit (general health, age, flexibility - other factors (diet, levels of hormones, physical and emotional state)

Cartilage

-a non-vascular structural material found in various parts of the body - does not adapt well to stress -there are many diff kinds of cartilage serving a variety of functions -forms most of the skeleton of infants - limited capacity for adaptation and healing- often will not heal - very susceptible to injury and tissue breakdown as the result of long term regular stress

air drag and dynamic equilibrium

-air drag reduces the acceleration applied to an object -since air drag is a force, you can say that it produces negative acceleration on a moving object (tends to slow it down) -for a falling object air drag changes until the terminal velocity of the object is reached

dynamic equilibrium

-all forces on a body or system in motion result in equal and oppositely directed inertial forces - inertial forces- the result of some acceleration acting on a body's mass (Ex: weight)

EMG application

-determining muscles or muscle groups to be targeted for training -analyze neurological effects of activity -therapy and rehabilitation

physiological measurements of skeletal muscle activity

-electrical activity - change in muscle length - change in linear limb displacement - change in linear whole body displacement - change in joint angle - force - torque

3 factors to increase the contribution of muscle tension in torque production?

-increase the firing frequency of motor neurons - increase the number of motor units recruited - recruit asistant agonist muscles

Effects of Eccentric Training

-more effective increases in muscle size and strength than with concentric training -more soreness and structural damage that with concentric or isometric training

Skeletal muscle fibers with aging?

-there seems to be a decrease in the number of FT fiber with age -infants and young children seem to have a lower percentage of Type IIb fibers than adults -significantly lower proportions of Type IIb fibers are found in obese versus non-obese individuals

low repetition, high intensity sets

-usually involves the performance of 1-5 repetitions, -HTMU are preferentially recruited while LTMU may be inhibited -primarily uses phosphocreatine system for energy, resulting in a very LIMITED PRODUCTION of lactic acid

Factors Affecting the magnitude of muscle force

-velocity of muscle shortening -length of muscle when it is stimulated -time interval between muscle stimulation and tension development (electromechanical delay)

cross extensor reflex

.2 - .5 seconds after the flexor reflex is activated in one limb, the crossed extensor reflex produces extension in the opposite limb

Power Explosive movements

olympic lifting shot put, discus throw sprinting jumping pitching

Muscular tension application

on average a muscle can produce a force of 90N for every square cm of area (90 N/cm2)- therefore increasing cross sectional through training will increase the potential force output

A single motor unit will contain?

only one type of muscle cell

Sensory deprivation

over time can result in memory loss, reduced IQ, personality changes, and hallucinations

deeper skin receptors

pacinian corpuscles - responds more to deep compression and HIGH frequency vibrations

Muscle spindles

parallel to the muscle fiber, composed of about 3-10 small muscle fibers encased in a sheath of connective tissue, designed to respond to changes an increase in muscle length (STRETCHING)

Parallel Elastic Component

parallel to the muscle fibers provided by muscle membranes supplies resistance when a muscle is passively stretched

golgi tendon organ

permits increased ROM by promoting muscle relaxation. designed to reduce damage to muscle and tendons

Important structures in the arch

plantar calcaneonavicular ligament plantar fascia

surrounding passive connective tissue (ligament)

pliable but relatively inelastic bands that allow free movement in a limited range of motion - damaged when stretched beyond normal range of motion- can contribute to joint instability

tendon and ligaments blood supply

poor in the tendons or ligaments itself depend on diffusion to supply inner fibers w/ nutrients

extensor thrust reflex

pressure on mechanoreceptors in the feet promotes contraction of extensors of the legs - provides the foundation for standing balance without conscious control

muscle tissue

produces the force that creates movement adapts readily to stress hypertrophy , hyperplasia fairly elastic- stretched or elongated without permanent damage

cellular hydration

promotes the stimulation of protein synthesis (tissue growth) and inhibiting protein breakdown

Conditioned response

putting a hand or arm up to block a movement

Components of the reflex arc

receptors afferent neurons interneurons efferent neurons effectors organs

Secondary movers

recruited when there is excess or additional resistance

obtaining integrated EMG from raw EMG

rectify signal take special average- root mean square (RMS) take area under trace of rectified signal per unit time

reflex supression

reflex responses can often be controlled or suppressed by signals from higher levels of the central nervous system

Which fiber type is larger in diameter?

FT fibers are larger in diameter

Which fiber type tends to fatigue more rapidly?

FT fibers usually fatigue more rapidly

when the angle of pull is equal to 90?

Fro = Fm

when the angle of pull approaches 0?

Fro approaches 0

Which fiber type will generate the greatest peak isometric contraction?

Intact FT and ST fibers will generate abut the same peak isometric force per cross sectional area of muscle

two forms of energy

Kinetic Potential

feedback

reflexes comprise a feedback mechanism - important for a variety of protective and survival functions- a response resulting from some form of input as in a reflex reaction that results from a stimulus - the source of our interaction with the physical world - involves input which is interpreted at some neural level

Type IIb fast twitch glycolytic

related to high intensity short duration activities (sprint races - 60 m, 200 m, etc)

Type IIa fast twitch oxidative glycolytic

related to higher intensity requiring endurance (middle distance running -1500m, 5000m, etc)

Type I slow twitch oxidative

related to lower intensity endurance activities (long distance running - marathon, etc)

Timing is important for exercising muscle

requires about 10 minutes of continuous activity for a muscle to reach an increased stable temperature. which means warm ups should be no less than 10 min- having to wait longer than 5 min may cause your muscles to cool down requiring a new warm up

stability

resistance to a change in equilibrium or resistance ot acceleration

Secondary spindle

respond only to the amount of elongation (STATIC response)

Primary spindles

respond to amount of elongation and speed of elongation (DYNAMIC response)- much stronger than the static response

General adaptation syndrome

response of body to stress, 3 stages

Elasticity

returns to length after being stretched

kinesthesis

senses of body and limb position and velocity, joint angle, and degree of pressure and tension being applied are critical for successful performance of many skills - important for fine motor control - useful for movements involving rapid changes of whole body orientation (diving, gymnastics)

chemoreceptors

sensitive to chemicals- taste, smell, detection of lower pH in blood caused by increased CO2 levels

reflex behavior can be altered

sensitization habituation

sources of input

sensory transduction sensory receptors

Fourier Transform

separates an irregular wave into its components- wave decomposition

muscle tissue exercise recovery

should be about 48 hours between bouts of intense exercise acting on any specific muscle. this allows for recovery from exercise induced damage

require reaching a state as close as possible to instability while remaining stable

starting positions in swimming and sprinting

Tm = Tr

static or isometric contraction- muscle length does not change

effector organs

stimulate or produce reflex action (effectors produce a EFFECT or response)

mechanoreceptors

stimulated by mechanical forces, usually pressure- sense of touch, baroreceptors which detect degree of lung inflation

exhaustion

stress accumulates beyond the bodys ability to resist or adjust to it, the stage in which the body structure or systems begin to fail, injury can occur during this stage

Force- Velocity relationship

a muscle shortens more slowly against increasing resistance (assuming the recruitment of the same number of motor units in each case)- concentric muscle force output increases the rate at which it is capable of shortening (velocity of shortening) decreases

withdrawl reflex

a protective reflex causing sudden withdrawal from a source of pain- also called the flexor reflex

How many fibers can a single neuron activate?

a single neuron can activate anywhere from less than 100 all the way to nearly 2000 fibers

equilibrium

a state in which all forces or torques acting on a body or system are balanced - a body in equilibrium is either motionless or moving at a constant velocity

Axon

a threadlike process forming the central core of a motor neuron

Contractile proteins

actin and myosin

Summation

activation of muscle fibers by rapid successive impulse until the maximum tension for that fiber is reached

3 stages of general adaptation syndrome

alarm reaction resistance exhaustion

joint capsule

also called articular capsule - forms an envelope surrounding synovial joints - made of two layers - lined with a synovial membrane

Strain energy

also called elastic energy, a form of potential energy which is based on a materials ability to store energy when its deformed, this storage of energy can apply to any material with an elastic component

Stretch reflex

also called myotatic reflex, activated by the muscle spindles in muscles undergoing rapid stretching, produces tension in the muscles being stretched, may serve a protective function to prevent joint damage

Motor End Plate

also called neuromuscular junction (myoneural junction) which is the area of contact between a motor neuron and a muscle cell (in humans there is one motor end plate per skeletal muscle fiber)

pain receptors

also called nociceptors

Plantar calcaneonavicular ligament

also called the spring ligament- made of yellow elastic tissue, critical for springiness of the arch, excessive elongation causes "flat feet", flat feet can result in increased ease of fatigue and additional stress on bones, muscles and joint superior to the foot

electromyography characteristics

alternating current AC- signal graphs as a series of changing positive and negative values

Primary movers

always recruited for a given movement

electrochemical stimulus

an action potential from a motor neuron

Stress

an agent process or condition that produces a demand on the body Ex: fatigue and muscle soreness produced by exercise, fever and other responses to illness, behavioral changes produced by emotional stress

Work

an applied force times the distance over which that force is applied

sensitization

an increase in reflex response- generally occurs in the first 10-20 responses - implies increased sensitivity to the stimulus that causes the response

Q 10 effect

an increase in temperature equivalent to 10 degrees celsius will cause a doubling of the rate of enzyme reaction

Hyperplasia

an increase in the number of muscle fibers as a result of resistance training (not a proven phenomenon)

Fine Movements

are produced by motor units with a small number of fibers (ex: eyes,fingers, etc)

Gross Movements

are usually produced by motor units with large number of fibers (Ex: large applications of force as in the gastrocnemius)

blood works better when warmed up

as blood temperature increases, so does the bloods ability to deliver oxygen

Effects of temperature on muscle activity

as body temperature increases - the speed of nerve and muscle functions increases - the force velocity curve shifts - fewer motor units needed to sustain a given force - the process that supply oxygen and remove waste speed up - overall improvement in speed, power, and endurance

Eccentric Contraction

as resistance (and therefore force output) increases beyond the isometric limit the muscle begins to lengthen, as resistance increases the rate of lengthening also increases

injury recognition tendons and ligaments

because of the limited nerve supply injuries in tendons and ligaments may not be recognized until they have become severe

fasciculi

bundles of muscle cells or fibers

tissue protection

cartilage is designed to handle compressive stress but easily damaged by shear or tensile stress

Neutralizers

change the effect or direction of movement when a muscle or muscle group contracts

exercise variations

changing the range of motion of an exercise or the position of a limb segment can change the muscles targeted by that exercise

lever systems

classified systems of torque, defined by position of force, resistance, and axis of rotation

Biarticular muscles

cross two joints

Multiarticular muscles

cross two or more joints

teloreceptors

deal with stimuli not touching the body

somatoreceptors

deal with stimuli that contact the body's surface

a decrease in time averaged tension

decreased level of stress will result in decrease in cross sectional area (atrophy) as well as shortening of these tissue in order to restore the OSE

immobilization

decreases proprioceptive feedback

surrounding passive connective tissue (cartilage)

designed to contribute to joint stability and ease of movement in a desirable range of motion- dance, gymnastics, and overhead throwing- damaged cartilage will result in less stable joint

proprioceptors

detect input regarding the position of body parts relative to each other - sense changes in the conditions of muscle and connective tissue - muscle spindles, golgi tendon organs

interoreceptors

detects input from within the body

exteroreceptors

detects inputs from outside of the body - teloreceptors - somatoreceptors

vestibular apparatus

detects the orientation of the head with respect to the direction of gravitational pull or acceleration. found in the structure of the inner ear

force arm

distance from an applied force to the fulcrum

resistance arm

distance from the resistance to the fulcrum

Tm < Tr

eccentric contraction- muscle lengthens

electrical activity measurement

electromyography- most accurate means of determining the specific muscles used in a movement or activity - direct (using needle electrodes) - indirect (using surface transducers)

Viscoelastic response of muscle tissue

enables muscle to stretch and recoil in a time dependent fashion

Kinetic energy

energy of motion

longitudinal arch (strain energy)

extends from the heel to the heads of the five metatarsal bones

Four behavioral properties of muscle

extensibility, elasticity, irritability, contractility

3 basic EMS techniques

faradic electrical stimulation galvanic electrical stimulation interferential electrical stimulation

flexibility at joints

flexibility relates to the range of motion that is allowed or restricted in a specific joint or combination of joints

Reflex example

flinching or blinking

high degree of static equilibrium

football linemen

components of lever systems

fulcrum moment arm force arm resistance arm

Multijoint muscles

gastrocnemius, hamstrings, rectus femoris - can combine to enhance movement

transverse arch (strain energy)

goes from side to side

require stable grips

golf, tennis, baseball

eustress

good stress- produces positive results

Properties of joint capsule

helps to hold bones together across synovial joints fairly tough and inelastic loose enough so as not to restrict normal joint movement functions very much like a ligament injuries take a long time to heal

95% of 1 rep max

high energy, high threshold motor units

mechanical stimulus

impact to the muscle may cause it to develop tension

Torque

in order to calculate a force must be perpendicular to the force arm, if the angle of pull isnt 90 degrees, a component of Fm that is perpendicular to Dfa must be calculated, this component is called the rotary force Fro since it produces rotation

Series Elastic Component

in series (in line) with the muscle fibers resides in the tendons stores elastic energy when tensed muscle is stretched

Anatomical Considerations

joint stability movement accommodation tissue protection

Stabilizers

keep a limb or body segment in a rigid or fixed position by static or isometric contraction

movement accommodations in back squat

knees go from an extended to a flexed position there is a natural lateral rotation of the lower leg once the knee flexes more than 10-15 degrees- to accommodate feet should be slightly turned out and knees in line with toes before starting the movement

acute loading

large force which greatly exceeds the stress which the body is conditioned or designed to handle- produces macrotrauma- traumatic injuries

muscle spindles

limit ROM through the stretch reflex. designed to prevent damage to joint and ligaments

40% of 1 rep max

low energy, low threshold motor units

Is mechanical energy = to work?

mechanical energy produced and work performed arent the same as caloric expenditure

Sarcolemma

membrane surround ing the muscle cells

levers in the musculo skeletal system

most are third class levers , disadvantage for force but advantage for speed of movement

low threshold motor units

motor units containing primarily type I muscle fibers

high threshold motor units

motor units containing primarily type IIb muscle fibers

Recruitment of motor units

motor units in a given muscle are not all activated at the same time

Tonic type cells

motor units which require more than a single stimulus to develop tension, found in the oculomotor apparatus (controls eye movement)

passive stretching

using a force other than antagonistic muscle groups to stretch a group of muscles. may involve the use of a partner, gravity pulling on the body, or even pulling with a non associated part of the body as in pulling on the ankles to stretch the hip extensors

repetitive loading

usually a lower level load that occurs repeatedly over an extended period of time- produces microtrauma- fatigue injuries

high repetition, low intensity sets

usually involves the performance of 12 or more repetition LTMU are preferentially recruited HTMU aren't significantly activated

moderate repetition, modern intensity sets

usually involves the performance of 8-10 repetitions activates a balance combination of HTMU and LTMU higher total % of muscle cells are activated in this method employs glycolysis for energy, resulting in lactic acid accumulation of lactic acid is associated with a surge in anabolic hormone levels

sensory receptor systems

visual apparatus vestibular apparatus auditory apparatus sensory nerves

constant state of instability

walking, running, etc

joint stability

to reduce that chance of injury the spinal column is rigidly arched or set to increase stability - when back squating

Plantar fascia

tough superficial band of tissue running almost the length of the foot, central portion is called the plantar aponeurosis, important for support of the longitudinal arch

how to train to improve muscular endurance?

training muscular endurance generally involves large numbers of repetitions against relatively light resistance, this type of training does not significantly increase muscle fiber diameter

TENS devices

transcutaneous electrical nerve stimulation- uses an electrical signal to block or interfere with pain signals- also found to stimulate endorphin production

the foot has 2 arches

transverse arch longitudinal arch

Bone injuries

traumatic- single event caused by large stress fatigue- injury that results from repeated small stress

Which fibers are recruited second?

Type IIa fast twitch oxidative glycolytic

Which fibers are recruited last?

Type IIb fast twitch glycolytic

warm up specifically

it is very important to warm up specifically to your sport to get a proper warm up

what is normal body temperature

37 degrees celsius

At what temperature is muscle function most efficient?

38.5 C or 101 F

How much percent of the bodies total weight does skeletal muscle occupy?

40-45%

There are approximately how many skeletal muscles in the human body?

434 muscles

How much quicker does fast twitch muscle fibers reach maximum tension versus slow twitch?

it takes FT fibers about 1/7 as long to reach maximum tension as ST fibers

Motor Unit

a functional group of muscle fibers containing a single motor neuron and the muscle fibers innervated by it

when you have equal tensions at the same angle of pull?

a larger value of Dfa implies a greater potential torque produced by the muscle

static flexibility

ROM allowed when a body segment is moved passively (outside factor such as a partner or the individual exerting force by muscles which aren't resisting the movement)

dynamic flexibility

ROM allowed when the body segment is moved by the individuals muscle actions at or around the joint

Which fibers are recruited fist?

Type I slow twitch oxidative

Tetanus

a condition in which peak fiber tension is reached but not released

habituation

a decrease in reflex response- sometimes called desensitization - occurs after a large number (greater than 20) regular occurrences of the stimulus - results in a reduced level of response to the stimulus- when the repetition of the stimulus is irregular, habituation doesn't occur

when body exceeds 40 degrees

a decrease in the efficiency of aerobic metabolism can occur since very extreme temperature can inhibit enzyme activity

Exercise

increases oxidative and therefore signal transmitting capacity of neurons

Which fiber type of individuals are generally able to produce more torque and power?

individuals with higher percentage FT fibers are able to generate more torque and power during movements

Plantar fasciitis

inflammation of the plantar fascia common among people in activities requiring a great deal of propulsion with the feet (jumping, running, race walking, soccer, etc)

Reciprocal inhibition

inhibits or prevents the development of tension in muscles that are antagonist to the muscles being stretched

active stretching

involves contraction of the muscles that are antagonistic to the ones being stretched. for example tensing the hip flexors to stretch the hip extensors

Total tension

is a result of addition of active and passive tension, parallel fibered muscles generate maximum tension when stretched to slightly more than resting length