Neuromuscular system and exercise cont. Flashcards
resistance training
systematic program of exercises involving the exercises involving the exertion of force against a load used to develop strength, endurance, and/or hypertrophy of the muscular system
CSEP and RT
beneficial to add muslce and bone strenthening activities using major muslce groups, at least 2 days/wk
ACSM and RT
strenthening exercises at least twice a wekk for health related benefits of such exercises
RT is used for 5
improving health - reduced risk of CV disease, type 2 diabetes, colon cancer, etc
injury rehab
improving athletic performance
improving dynamic stability and preserving functional capacity
changing physical appearance
4 specificity in muscular fitness
muscular strength
hypertrophy
power
muscular endurance
overload in muscular fitness is achieved by manipulating 4
load - amt of weight assigned to an exercise set
- % of 1RM
- most weight lifted for a specific # of reps
volume - load x reps x sets
rest intervals
frequency of training
higher volumes are associated with
increases in muscle size
load for muscular fitness 3
heavier loads - strength and power
mod for hypertrophy
light - endurance
reps for muscular fitness
lowest to highest - power to strength to hypertrophy to endurance
sets for muscular fitness
single set training may be appropriate for untrained ind. but higher volumes are necessary to promote further gains in intermediate and advanced participants
rest interval
short rest periods utilized for building endurance
frequency of training 3
novice - 2-3x/wk/muscle gp
intermediate 3-4
advanced 4-7
RM for strength and power
2-7
RM for hypertrophy
7-11
RM for muscular endurance
13-20
progression
increase in exercise stress - (intensity) once adaptation has occurred
- 2 for 2 rule - if 2 or more reps over the assigned goal can be performed in two consecutive workouts for a certain exercise, weight should be added to that exercise in the next training session
rest/adaptation
1 day/muscle gp
individualizaion
adaptation occurs at diff rates in diff ppl (genetic disposition)
maintenacne
1 session/wk sufficient
neuromuscular adaptations to RT (muscle function) -4
improve muscle strength and endurance by 25-100% with 2x/wk training
increased cross sectional area
both males and females are similar
regarless of age
2 possible mechanisms for increased muscle size
hypertrophy - growth in cell size
hyperplasia - increase in the number of cells
hypertrophy for humans
hypertrophy (3)
increase in muscle fibre cross sectional area
- increase myofilament content in myofibrils
- myofilament density - space between myosin filaments does not seem to be modified
2 mechanisms of hypertrophy
signaling cascades leading to increased protein synthesis satellite cells (myosatellite) - muslce stem cells - located above the sarcolemma - quiescent unless activated can fuse with existing fibres
myostatin
enhances muscle protein breakdown - limit skeletal muscle cell hypertrophy
cast induces muscle ___
atrophy
leucine and hypertrophy
activates mTOR which leads to hypertrophy
path of satellite cells
proliferative and commit to differentiation (myoblast) then fuse into myotube and mature into myofibre
myostatin related muscle hypertrophy
rare genetic mutation that prevents the body from producing myostatin - characterized by increased muscle size in ind with increased muscle strength and reduced subcutaneous fat pad thickness
myostatin inhibitors
not regulated so dont take it
anabolic steroids
synthetic substances related to the hormone testosterone that promote the growth of skeletal muscle as it binds to intracellular receptors to activate the DNA to dictate the synthesis of a protein
How to achieve greatest gains
androgen administration with RT
mechanism of hypertrophy
increased protein synthesis in skeletal muscle and activation of satellite cells
5 adverse side effects of anabolic steriods
CV disease - decreased HDL
endocrine: virilization, testis atrophy, prostatic hypertrophy, gynecomastia ( covertd into estrogen) , erectile dysfunction
liver: hepatitis, adenoma, carcinoma
musculoskeletal: premature epiphyseal plate closure, increase bone density, decrease tendon strength
psychiatric: aggressiveness, extreme mood swings- depression
virilizaton
females have male hair growth
gynecomastia
male breast development
hyperplasia in humans
hard to know - challenges directly measuring muscle fibers
hyperplasia in animals
RT
mechanisms of hyperplasia
satellite cells - form new fibers
skeletal muscle fibre splitting - hypertrophied fibers break apart
hyperplasia in humans
young dead ppl - TA in dominant leg in young males had more muscle fibres than non dominant leg
increased cross sectional muscle area in powerlifters - not associated with increased muscle fiber size
- only in first years of life
can change in muscle size be longitudinal?
yes, increase or decrease the number of sarcomeres in series, if its contracted all the time, sarcomere gets removed and lose length
5 initial increases due to neural adaptation
increased CNS drive
increased synchronization of MU ( agonists, synergists)
enhanced coordination of MU - less resistance from antagonist muscle
increase in the size and number of motor end plates
reduced inhibition by reflexes
whats associated with the greatest neural adaptations?
high intensity (95-100% 1RM ) but does plateau - no change yet in actual muscle fiber
limb immobilization/suspension and ____ and ______ can lead to 4
spinal cord injury/space flight
- muscle atrophy (reduced CSA) - SO are the first to atrophy because they are the first to be activated
- muscle fiber type prfile goes from slow to fast twitch
- muscle oxidative capacity is reduced
- general weakness
can muscle fiber type change with training? (5)
minor modifications
not conversion, but the contractile properties and metabolic capacities can shift
modify their expression of myosin heavy chain
after extensive training
neural and structural modifications are much greater
you can only adapt - harder to become a FT
muscle fiber adaptation to RT for muscle size and structure -3
whole muscle and muscle fiber CSA
myofibril protein content
connective tissue adaptation to RT - 3
increased collagen synthesis
portion of connective tissue to skeletal muslce
increased collagen stiffness
neural adaptation to RT - 3
increased MU recruitment
increased synchronization
decreased GTO reflex
metabolic adaptation to RT - 3
increased glycogen, PC, creatine phosphokinase
hormonal adaptations to RT - 3
inconsistent findingds for testosterone and cortisol
no change in GH
increase in insulin like growth factor
detraining and strength
strength is maintained longer than many other training adaptations - 15-30% decrease in strength reported with 30-32 weeks of detraining
muscular adaptations to aerobic enduracne training programs
increase in SO fibre size
possible transition in FG to FOG
concurrent training
integration of endurance and resistance based training into a training program
strength gains and concurrent training
thin strength gains because the two rate of force pathways inhibit each other, one goes through IGF, then mTOR then translationsal activity then protein synthesis, the other goes through glycogen AMP then alpha 1 then mitochondrial biogensis for aerobic capacity
RT proves 6
reduced mortality, improved functional capacity and cardiometabolic health, strength, muscle mass, BMR
what improves insulin sensitivity?
aerobic training and RT
the nervous system
controls voluntary and involuntary movement - responsible for gross and find motor skills
somatic NS can be activated by
concsious thought and peripheral sensors
proprioception
perception of movement of body plus its orientation in space
proprioceptors aer located in
tendons, muslce and joints
- muscle spindles
- golgi tendon organ
cerebellum
integrate info from the somatic receptors, vestibular aparatus and visual and auditory stimuli
spinal cord receiving info
afferent info caried up the spinal column to the somatosensory cortex through ascending tracts - pain/nocireceptors
spinal cord sending info
alpha motor neurons are activated by pyramidal or extrapyramidal descending tracts
descending tracts (2)
pyramidal tract
extrapyramidal tracts
pyramidal tract
voluntary corticospinal tract - neurons synapse directly onto alpha motor neurons
extrapyramidal tract
carries info that controls muscle tone and posture as well as head movements in response to visual stimuli and changes in equilibrium - indirect, polysynaptic pathway activation of an alpha motor neuron
direct synapse means
monosynaptic
muscle spindle furction and composition
proprioceptive stretch receptor
composed of fluid filled capsule
intrafusal muscle fiber and afferent neurons
intrafusal muscle fiber
nuclear bag fibers - thicker and attached to connctive tissue
nuclear chain fibers - thinner and shoter
afferent neurons
annulospiral - myelinated
- monitor rate of length change
flower spray sensory neurons - monitor relative muscle length and high threshold of excitation
alpha gamma motor neuron coactivation
when an alpha motor neuron is activated a gamma motor neuron is also activated to ensure that muslce spindle is always responsive
alpha motor neurons
activate extrafusal muscle fibres
gamma motor neurons
activate intrafusal muslcle fibres
reflex
rapid, involuntary response to stimuli in which a specific stimulus results in a specific motor response - does not require the higher brain centres but higher brain centers are informed
5 componenets of a reflex arc
receptor afferent sensory signal integration center - processing of signal, integration with association neurons efferent motor neuron effector organ (skeletal muscle)
reflexes can be ___ and ___
excitatory and inhibitory
myostatic stretch reflex
stretch stretch reflex
occurs with rapid ___ of a muscle, afferent impulses along the annulospiral neuron travel to the spinal cord, resulting in the activation of the agonist muslce and the reciprocal of the antagonist muscle (inhibited by neurotransmitters)
plyometrics
rapid stretches and stimulate the muscle spindels causing a reflexive muslce action to increases force production
asynchronized activation of alpha and gamma
gamma first, can be coordinated
golgi tendon organs
proprioceptors in the tendon of a muslce - monitors mucle tension
inverse myostatic - reciprocal activation to protect the muslce so it doesnt over tighten/contract -
inverse myostatic reflex
activated by muscle contraction and stretch, afferent signals travel to the spinal cord resulting in relaxation of the agonist muscle and reciprocal activation of the antagonist muslce
- protext the muscles and tendons from damage
untrained vs trained in plyometric training
kicks in much earlier than in untrained because you stretch - with eccentric, after training golgi woud be turned off and more power from contraction
volitional control for
important for skilled movement function at the level of a single motor unit.
myoelectric prosthetic
take sensors to mount them on signals for them to take it and relay - train ind units -
volitional contraction of a muscle alters
muslce tension, length, and position ___
muscular changes due to volitional contractions are sensed by
receptors and transmitted to the central nervous system through afferent neurons
continual integration of this info and readjustments by the NS ensures
coordinated movement
flexibility
ROM in a joint or serioes of joints that reflects the ability of the musculotendon structures to elongate within the physical limits of the joint
3 types of stretching
ballistic stretching
static stretching
proprioceptive neuromuscular facilitation
ballistic stretching (3)
an action reaction bouncing motion, in which the jts involved are placed into extreme ROM by fast, active contractions of the agonistic muscle groups
activates myostatic stretch reflex
risks of injury
static stretching
muscle to be stretched slowly put into a position controlled maxiaml or near maximal stretch by contraction of the opposing muscle group and held for 30-60 seconds
- activates the inverse myostatic reflex if stretch continues for 6 seconds
proprioceptive neuromuscular facilitation
muscle to be stretched is first contracted maximally, then relaxed and either actively or passively stretched
- maximal contraction activates the inverse myostatic reflex - in the
why increase the agonist muscle when stretching
increase the ROM
physiological responses to stretching (2)
improves ROM
before exercise may lead to performance deficits in strength, power, and reaction time
flexibility training (2)
does not limit strength, power, and reaction times - may contribute to reduced DOMS after eccentric dynamic exercise
does stretching and flexibility prevent injury?
no clear evidence
why does stretching help with eccentric dynamic exercise
longer muscles
take home msg for stretching
evidence on injury prevention, performance and health is not as strong as aerobic and RT - AT - RT - flexibility
what are all the factors that can affect muscle tension
genetics - fiber 1 and 2, 2 has more force length tension CNS drive - central farigue Jt angle Velocity of contraction - eccentric is neg velocity and has lots of force hypertropy elasticity reflex age, disease, injury, disuse
