Stretching

what is a big imfluence of compliance, and why

# of crossbridges more you have, less compliant -look at when in action -active crossbridges more important

what is strain

% change in length

what is stress

(N/m2) tension per unit of cross sectional area

whats involved in autogenic inhibition, location, what does it respond to

-GTO -tension receptor located primarily in the musculotendinous junction -responds to increased active and passive tension -inhibits own muscle

what did stretching have an impact on

-ROM of leg (kick) -foot speed at impact (kick) -balance -reaction time -movement time

how does warm ups prepare teh body for exercise

-accelerating metabolism -decreasing intramuscluar resistance -increasing mechanical efficiency -increasing ROM/flexibility -increasing speed and F of muscle contraction

what besides injury does stiffness and flexibility have to do with

-age -CNS(need to retrain)

how can it cause injury

-as comp increases, decreased energy able to be absorbed -different sarcomere lengths can injure muscle during ECC even if not over stretched -mild stretches even cause cytoskeleton damage -stretch tolerance masks pain

what does warm up increase

-body and muscle temp -blood flow to muscles -muscle compliance -speed of nerve impulses -O and energy substrate delivery to working muscle and removing waste products -O release from hemoglobin and myoglobin

what do ice and heat do for stretching

-can cause to go farther which can help tolerance but damage muscle

how does the nervous system affect output

-changes in it can change musculotendinous units which can be detrimental

what is reciprocal inhibition

-contracting tricept inhibits the bicep -agonist contraction helps inhibit antagonist and stretchies it

what can stretching do to joints

-decreased stability makes joint motion less efficient

what are adverse effects of stretching

-decreased strength up to 1 hour -increased arterial blood pressure -some evidence shows decreased running economy with increased flex

what happens to an injured muscle

-dont have same elastic properties so longer stretches required -can neurologically inhibit

what is the strongest predictor of injury risk

-fitness level -across all soft tissue and bone injuries (except ankle sprains) -least fit 14x more likely to get lower limb injury -modifiable risk factor for injury

how does increased ROM/flex check out

-has been demonstrated to increase joint flex -most likely stretch tolerance*** -some support PNF stretching as most effective

why is stiffness/stretching good sometimes

-if less complient, F transmitted against muscle unit quicker (for when need speed and F) -so dont want complient unit bc more elastic energy stored and cant transmit as quickly -with too much stretching, firing GTO which impedes contraction of that muscle

what are the goals of stretching

-increase ROM/flex -improve performance -decrease soreness -decrease risk of injury

wat is increased flex mostly from and why

-increased stretch tolerance -some reflex inhibitions -change in viscoelasticity -lower crossbridging -some say PNF

how does increased ROM/flex indirectly decrease it as well

-indirect decrease due to reflex inhibition and therefore changes in viscoelasticity from decreased crossbridging

what are factors in how frequent one should stretch

-joint irritability -some require longer duration, reps, and freq

what activities is static stretching bad

-leg strength -jump height -peak jump force

how does improved performance check out -what is advantageous vs disadvantagous

-less stiffness is advantageous for stretch-shortening cycle activity -less stiffness is a disadvantage for isometric and concentric performatnce

viscous, def

-like liquid, means can have a permanent change or plastic deformation (silly putty)

how can stretch duration be bad?

-may be detrimental on performance -1 min stretch has less jumping impairment than 2-4 min -strong ev of impairment when static stretch > 90 sec (3rep of 30 sec)

what are the physiologic basis for passive stretching

-mechanical stretch of soft tissue -autogenic inhibition: GTO

what is optimal flex

-med flex -most and least flexible subjects at increased risk of injury

what grades are for passive stretching

-mobilization for grades 3 and 4 (more tissues around joint than muscle)

whats involved in mechanical stretch of soft tissue

-muscle -parallel and series elastic components -articular structure -tintin(stiffness component)

what resistance is there to stretching

-neurophysiological constraints (contractile activity should be minimized) -biomechanical constraints (stiffness)

does stretching decrease risk of injury

-no evidence, more likely to cause actually

look at study on slides 34-35 results on flip side

-no impairments in rx time or balance when 6 sec static with warm up -6 6sec static streth with/without 5-10 min aerobic activity improved height, muscle T, and balance -all conditions improved

what does sarcomere length have to do with injury

-no way of knowing the different lengths -can damage easily -can damage cytoskeleton bc more F more likely to damage(especially with eccentrics)

how frequent should one stretch

-one stretch per day per muscle group -4 stretches 4xday can be beneficial after injury

muscle spindle (1A) do?

-primary nerve ending afferent responding to quick stretch (1A) -1A doesnt inhibit but causes facilitation of contraction of own muscle -quick stretch, help cotract

why is location of weight important in passive stretching

-put weight closer/farther -farther has more impact -can control speed, control, and application of overpressure

what are cautions with ballistic stretching

-quick stretch stimulates muscle spindle stretch reflex -may cause microtrauma if too forceful -elastic changes greater than plastic so may not be lasting

what is viscousness dependent on

-rate and time dependednt -slow force over long time

what do warm ups do cellularly

-reboots waste -blood flow -more O -N system -lactate to liver -O released form hemo and myoglobin

whats the deal with warm ups, whats its downside

-some support for it being more important for preventions -amount of warm up is critical bc too much =fatigue which can increase injury risk

what should stretching duration be like for static, weights, and active

-static: 30 sec (60 if older) -weights: 15-30 min -hold at least 8 (Bohannan) -active: 6-10 sec contract 2-5 relax 15 sec stretch or contract 6-10 (antagonist or push down)

what are biochemical constraints to stretching

-stiffness of tissue -compliance -stretch tolerance

how do you maintain the range (easy to lose)

-strengthen agonist and antagonist in new range -home exercise programs -splints -serial casting

what is a compliant muscle to athletes

-temp imede performance for high intensity -more compliant sotres more elastic energy over long period of long distance

what happens with too much static stretching

-too much GTO firing which neurally impeeds its own muscle

what are various approaches to prevent injury/enhance performance

-warm up -stretching -strength training -plyometrics -proprioception training

which muscle type is most flexble and which more risk for injury

1/slow twitch- for flexibility 2- for injury

what percent can damage muscle

20% past resting

what duration is needed for increased flex

6-90 minutes -extensive programs for several weeks has produced increased flex that lasts for several weeks -hypermobility needed to stretch to maintain it

stretching Def

a maneuver used to lengthen shortened soft tissue structures as well as maintain range

what does warm up decrease

activation energy for cellular reactions and muscle viscosity

flexibility def

an intrinsic property of body tissues that determines the range of motion that can be achieved without injury at a joint or group of joints

what is the physiologic basis for active stretching

autogenic inhibition:GTO reciprocal inhibition

what should a person do to avoid injury from stretching

avoid prolonged static stretching prior to performance and minimize shorter duration stretching

is 1A good for stretching muscle good or bad

bad -dont want to contract -want to relax -makes contraction harder and need more F -can cause microtrauma

what is the stiffness of tissue

change in tension/unit change in length (how much stretch can be applied to a tissue/change in length) -stress and strain are factors -if stiffer needs more F to get change

what is stretch tolerance

feel less pain for the same force applied to the muscle -as stretch it improves -more important than decreasing stiffness

what is dynamic stretching

functional stretching exercise that uses sport-specific movements to prepare the body for activity -controlled movement thru ROM -better than static as a warm up -moving joints mimicking activity exactly

GTO

golgi tendon organ

what does elastic deformation need

high force, short duration ex: balistics

when do you see the biggest improvement in range, why

in first 4 reps of stretching -decrease in T and increase in length

viscoelastic deformation

increased muscle length can occur with sufficient duration and magnitude of stretch, but muscles elastic property limits magnitude and duration of the increased length

what does GTO do

inhibit own muscle for contraction

what happens with GTO as you lengthen a muscle

it feels tension, wakes up and fires -causes inhibition -protects from tearing

what do you want if you want plastic deformation

low force over long duraiton

what is the resistance in static stretching from

more vicoelastic properties than contractile components

what happens as you increase extensibility to the passive length tension curve

no change not maintaining extensibility

does stretching decrease soreness

no evidence -doesnt do reverse tho

what are stretching methods

passive static active isometric ballistic dynamic

elastic

permits recovery from deformation or elastic deformation (rubber band)

what is active stretching and how

proprioceptive neuromuscular facilitation (PNF) -contract/relax -hold relax -contract/relax/contract -contraction of antagonistic muscle

what is ballistic stretching

rapid lengthening of the muscle by use of jerking or bouncing movements -high force, fast, bouncy

what is compliance

reciprocal of stiffness (change in length per unit change in tension) -more F to get it to do something if less compliant

what is passive stretching and what forces does it have

slow, sustained muscle lengthening -weight of part plus gravity -weight of part plus gravity plus external load -manual overpressure

what is static stretching

slow, sustained muscle lengthening held by subject for 15-60 seconds -typically 30 is good -over 65 years old do longer

what is isometric stretching

static stretching against an immobile force -not contracting, but using resistance of something

what are types of flexibility

static: range measured with goniometer (holding) dynamic: resistive to active motion around joints

what do you want stretching intensity like

stretch to point of discomfort -pain tolerance -avoid reflex spasm (from pain)

what does improved flexibility have most to do with?

stretch tolerance

what is stress relaxation

stretching and T decreases and can go farther into range

what is different between short and long muscles in the T vs length graph

the shorter muscle has more T per unit length change longer muscles are more compliant and less stiff than shorter muscles

what are major factors in stretching

type intensity duration frequency force duration (elastic v plastic) temperature

what is flexibility depend on

viscoelasticity of muscles, ligaments and connective tissue

what are viscoelastic properties

viscous elastic deformation

what is more important than stretching

warm up

how does temp affect stretching

warmer has more extensibility and less stiffness increased ROM

who are more flexible

women and chldren

do you need full passive ROM to get full active ROM

yes

is it difficult to maintain increased flexion for long, and what is needed to maintain it

yes hypermobility