KIN 225-Midterm 1
True or False: The goal of static stretching is to fatigue the muscle spindle
True
True or False: Functional MRI measures areas of increased or decreased oxygen consumption in the brain
True
What do Nodes of Ranvier do
allows maintenance of the action potential strength
When does bilateral deficit appear/disappear
Disappears with bilateral training Increases with unilateral training
The ATPase determines time to peak tension during contraction
myosin ATPase
What is the main storage form of a carbohydrate in skeletal muscle
Glycogen
If all your motor units are active, how else can you increase your force of muscle contraction?
Increase firing frequency of your motor units
True or False: When ADP and Pi are bound to myosin, myosin forms strong cross-bridges with actin
False
True or False: Type I motor neurons have a greater amount of myelin
False
When ADP and Pi are bound to myosin, myosin forms strong cross-bridges with actin. True or False
False
What are GTO's
-Receptors found at the junction between tendons and muscle fibers -Activated by tension -Inhibit muscle contraction
What are Muscle spindles
-Receptors in the muscle that detect stretch in the muscle. -They are responsive to both the rate and amount of stretch. -They send excitatory input to the motor neuron in the spinal cord -Cause muscle contraction
How does bilateral deficit occur
-Sensory input from one limb causing inhibition on the motor neuron innervating muscle of the opposite limb -Inhibition at higher brain centers -stabilization
What are the causes of bilateral deficit
-Sensory input from one limb causing inhibition on the motor neuron innervating muscle of the opposite limb -Inhibition at higher brain centers (inhibition of one side of the motor cortex on the other)
What other changes occur with strength/sprint training to minimize loss of speed with the fibre type shifts?
-Type IIx fibres increase in size more than there muscle fibre types; therefore occupy a greater muscle fibre volume -Improvements in biomechanics/efficiency of movement
What is an enzyme
-a protein -a molecule that increases the rate of chemical reactions -could increase in concentration following exercise training
What is one problem with eccentric training?
-lots of DOMS May feel a lot of muscle damage
Explain the Cross-bridge cycle
-myosin pulls on actin so that actin can slide past myosin -Calcium is needed to "dis-inhibit" actin -ATP split for energy to activate myosin before attachment and then binds to myosin to allow dissociation of actin-myosin cross-bridge
What are the two types of Muscle Fiber Classification?
1) Classification based on myosin heavy chains (ATPase activity): Type I, type IIa, type IIx, Type IIb 2) Classification based on "twitch" properties "slow twitch" "Fast twitch a (FTa)" fast twitch x (FTx) "Fast twitch b (FTb)
What are the three types of muscle contraction
1) Concentric 2) Isometric 3) Eccentric
Concentric contraction is enhanced by previous stretch because of:
1) Stretch Reflex 2) Elastic rebound of muscle
What are two ways An action potential can be generated
1) Temporal summation: One or few neurons can deliver repetitive stimuli over a short period of time to the motor neuron 2) Spatial summation: A bunch of excitatory post synaptic potentials can be delivered from different neurons to a motor neuron
Explain 3 ways to control movement
1) Voluntary Movements 2) Reflexes 3) Rhythmic Movements
If introducing eccentric overload into someone's strength training program, what is the best initial prescription?
1-2 sets of 10 reps every 3rd day
Put the following events, which occur during muscle contraction, in proper order: Calcium binds to troponin Actin and myosin form cross-bridges Calcium is released from the sarcoplasmic reticulum An electrical impulse travels down the muscle fibre membrane and down the transverse tubules Troponin lifts tropomyosin off actin An impulse is sent from a motor neuron in the spinal cord to the muscle fibre membrane ATP is split on the head of the myosin to release energy
1. An impulse is sent from a motor neuron in the spinal cord to the muscle fibre membrane 2. An electrical impulse travels down the muscle fibre membrane and down the transverse tubules 3. Calcium is released from the sarcoplasmic reticulum 4. Calcium binds to troponin 5. Troponin lifts tropomyosin off actin 6. ATP is split on the head of the myosin to release energy 7. Actin and myosin form cross-bridges
What % of strength is increased in the untrained limb with cross-education
52%, If you train one limb and increase of strength by 10lbs, the untrained limb will have 5lbs increase of strength
What is Tapering
A "taper" is a reduced volume of training athletes often use in the 1-2 weeks before an important competition
What is a motor unit?
A neuron and all of the muscle fibers it innervates
What is a concentric contraction
A concentric contraction causes muscles to shorten, thereby generating force.
What is the main fuel source when performing an aerobic exercise
A fatty acid
What is tropomysin
A regulatory protein A protein that blocks the binding for myosin on action
What are some of the benefits of training by plyometric?
A) increase your ability to activate the stretch reflex B) increase your ability to use stored elastic energy from muscle C) increase your ability to inhibit the Golgi tendon organ
What is the main molecule used for energy
ATP
What are contractile proteins
Actin and Myosin They interact to form cross-bridges to generate force
ATP is broken down by what enzyme? What is the product
ATPase, leaving ADP + P
What causes a muscle cramp during or after intense exercise?
Abnormal activation of the muscle spindle Electrolyte imbalances Dehydration
These proteins make up the thin myofilament
Actin, troponin, tropomyosin
Explain the propagation of action potential
Action potential is propagated along the axon of the motor neuron. The Axon is covered by myelin (a lipid sheath). At certain points along the axon, there is a space in the myelin ("nodes of Ranvier")
What is the importance of using EMG?
Allows you to assess which muscles are active during specific exercise Allows you to assess the amount muscles are activated Allows you to assess which muscles are under strain during work situations (important for injury prevention)
What are some of the causes of the "repeated bout effect"
Alteration in neural recruitment of muscle fibres (more type I fibre recruitment on the 2nd bout) Sarcomeres might become stiffer after the first bout of eccentric exercise Weak sarcomeres are damaged during the first bout of eccentric exercise and replaced by stronger sarcomeres.
Which molecule contains nitrogen
An amino acid
What change in fiber type composition do you think will happen after months of intense endurance training?
An increase in Type I fiber because type I is slow-twitch so it breaks ATP down over a longer period of time which is ideal for endurance training
This athelete would have a low bilateral deficit
Anything using bilateral training and use of both limbs equally. (vball blockers, rowers)
An individual suffers a spinal cord injury that results in lower leg paralysis. Following 3 months of paralysis, they start a training program whereby their leg muscles are electrically stimulated. How would their fibre type composition change immediately following paralysis and during their training program?
Anytime you have a subjective to P.A, you go from slower to faster. Go from fast to slower for initial paralysis, type IIx to type IIa . Immediately from slow to fast following paralysis IIa fibers to type IIx
What does plyometric training allow for?
Better co-ordinate transfer of elastic energy Activate Stretch reflex Inhibit Golgi Tendon reflex ("disinhibition") Accelerate throughout a complete range of movement
Which of the following lead to muscle contraction and which lead to muscle relaxation? -Pumping of calcium into the sarcoplasmic reticulum -Binding of calcium to troponin -Binding of ATP to the actin-myosin cross-bridge broken down, at the end you need binding of ATP) -Lifting of tropomyosin off actin
Binding of calcium to troponin -contraction Pumping of calcium into the sarcoplasmic reticulum -relaxation Binding of ATP to the actin-myosin cross-bridge -Relaxation (end of cross-bridge cycle, initially atp is broken down, at the end you need binding of ATP) Lifting of tropomyosin off actin -contraction
Which of the following lead to muscle contraction and which lead to muscle relaxation? -Binding of Calcium to troponin -Pumping of calcium into sarcoplasmic retic -Binding of ATP to the actin-myosin cross-bridge -Lifting of tropomyosin off actin
Binding of calcium to troponin -contraction Pumping of calcium into the sarcoplasmic reticulum -relaxation Binding of ATP to the actin-myosin cross-bridge -Relaxation (end of cross-bridge cycle, initially atp is broken down, at the end you need binding of ATP) Lifting of tropomyosin off actin -contraction
this part of the nervous system is involved in controlled posture and hand-eye coordination
Brain stem
How can a type IIb be converted to a type I muscle?
By applying chronic low-frequency electrical stimulation to a type IIb muscle
How can Type I muscle be converted to a faster muscle
By applying phasic high-frequency electrical stimulation to a type I muscle, it can be converted to a faster muscle (i.e. type IIa, IIx, or IIb).
A soccer team has a game on Saturday. At the end of the Thursday practice the coach gets his players to run up and down a steep hill repeatedly. This is a drill they have not done before. What error has the coach made?
By working them after a practice without any stretching will cause DOMS and will decrease the amount of power. They may need more recovery time in order to play sufficiently.
Explain the contraction process in correct order
Calcium binds to troponin Tropomyosin is lifted off actin Myosin binds to actin Myosin cross-bridges pull on actin
What was the spinal cord cat experiment
Cats had their spinal cords transected so that their legs were paralyzed By placing their paws on a moving treadmill, they eventually learned to walk on the treadmill This indicates that you can take a "voluntary movement" and make it "reflexive"
What is the CNS and what is it comprised of What is the PNS and what is it comprised of
Central nervous system: Brain and the spinal cord Peripheral Nervous system: nerves extending from the brain to spinal cord, and sensory receptors extending from the periphery to the spinal cord and the brain
What is the change in electrical charge across the muscle membrane during contraction/relaxation?
Contraction: Sodium coming in, potassium leaves. Relaxation: Potassium coming in, Sodium leaves.
What is myosin
Contracts with actin during muscle contraction Increase with strength training
What are D.O.M.S.
Delayed onset muscle soreness Can last for days One bout of eccentric exercise seems to protect you from soreness on a subsequent bout (called the "the repeated bout effect"
What does fMRI, Functional Magnetic Resonance Imaging do?
Detects changes in hemoglobin oxygenation i.e. indicates where there are increases or decreases in oxygen consumption in the brain Gives an indication of what areas of the brain are activated or de-activated
Action potential propagation: Down the axon
Due to influx of sodium at successive points along a membrane
This technique is used to assess the activity of individual motor units
EMG
What do the two heads on myosin do
Each head has one heavy chain The type of heavy chain determines the ATPase activity
What muscle fibre type change would occur with the following types of training? Consider type IIx, IIa, and I fibres: -Endurance Training -Strength Training -Sprint training -Detraining
Endurance training, some IIa-I, IIx- IIa Strength training, IIx-IIa Sprint training, IIx-IIa Detraining, IIa-IIx, I - IIa with extreme inactivity
True or False: Fast twitch motor units usually have a higher number of muscle fibers compared to slow twitch motor units.
False because your Nervous system can change
True or False: When an electrical discharge (known as an "action potential") is generated in the axon of a motor neuron, only a portion of muscle fibers innervated by that axon will contract if the action potential isn't strong enough
False, it will innervate ALL of the muscle fibers.
True or False: Once all your motor units are recruited you can no longer increase force output
False, you can generate more force by increasing firing frequency
A single motor unit can have a mixture of fast twitch and slow twitch muscle fibers. True or False
False, you can only have one type of fiber
More myelin or thicker axons results in what?
Faster conduction velocity of the axon. Fast twitch motor neurons have thicker axons
Where do motor units receive information from?
From the motor cortex in the brain AND sensory receptors
One of the main roles of this receptor is to protect the muscle from injury
GTO
You can increase your strength by inhibiting this receptor
GTO
Training on an unstable surface allows for what:
Great muscle recruitment of the trunk, (abs, lower back)
Which of the following shortens during a contraction? Myosin Actin The I-band A-band Sarcomere
I-band and Sarcomere Actin and myosin only slide past each other to allow sarcomere to contract
Where are most enzymes involved in metabolism
In the Mitochondria
Where in the cell can you find DNA
In the Nucleus and Mitochondria
Where are glycolytic Enzymes found
In the cytoplasm
What is a plyometric contraction
Involves first a rapid muscle lengthening movement, followed by a short resting phase, then an explosive shortening movement.
What happens when a large amount of calcium is released in a muscle fiber
Many troponins will be bound with calcium Most tropomyosin will be lifted off actin Many actin and myosin cross-bridges will be formed
What is MAV ?
Mean Absolute Value Used to determine the amplitude of the signal
This characterisitic of EMG decreases as a muscle fatigues. It is not an average value.
Median frequency
Mitochondria are often found around sarcoplasmic reticulum and the myofilaments in muscle fibres. What is the functional significance of the location of these mitochondria?
Mitochondria are found there and supply ATP myosin to allow contraction and relation -Calcium channels open up, calcium just opens up
Mitochondria are often found around the sarcoplasmic reticulum and the myofilaments in muscle fibres. What is the functional significance of the location of these mitochondria?
Mitochondria are found there and supply ATP to myosin to allow contraction and relaxation Calcium channels open up, calcium just opens up
Caffeine increases release of calcium in cells. Considering the function and structure of sarcomeres, fully explain how this may increase the force of the contraction?
More calcium in the muscle allows for more binding to troponin. This causes more tropomyosin to reveal more actin binding sites. More binding sites allows for more cross-bridging between actin and myosin which produces a stronger contraction in the muscle. More cross-bridging = more contraction
What neuron is fast twitch?
Motor Neuron A
If muscle #1 had a lower frequency of EMG bursts than muscle #2, which muscle do you think would have the greatest percentage of type I muscle fibres?
Muscle 1 because lower frequency of EMG bursts causes a greater percentage of type I muscle fibres
What is the Force-muscle length relationship and what is it due to
Muscle force varies with the length of the muscle This variation in force is due to variation in actin-myosin overlap.
This covers the axon and ensures that the action potential is conducted quickly
Myelin sheath
What is myoglobin
Myoglobin is a protein in your muscle responsible for transporting oxygen from the muscle membrane-capillary interface to the mitochondria. -Myoglobin gives the muscle a red pigmentation.
Which filaments are thick and thin?
Myosin = thick Actin, troponin, tropomyosin = thin
What two locations is the enzyme ATPase found?
Myosin head and in the sarcoplasmic reticulum
Do The Nodes of Ranvier allow for faster conduction of the action potential down an axon?
No, The purpose is to reinforce the charge and slow down action potential
What is Exertional Rhabdomyolysis an what are some characteristics
Occurs when you preform a high intensity exercise when you are not used to such intensity -Muscle damage -Kidney damage -Elevated myoglobin in the blood
What bone cell is involved in bone formation?
Osteoblasts
Which is more permeable: Sodium or Potassium?
Potassium Potassium leaks out easier than sodium leaks in
What would be the purpose of having inhibitory input to a motor neuron (this would essentially prevent muscle from contracting)?
Protection from injury if the muscle is contracting too intensely Maintain the balance of opposing muscles
What is voluntary movement:
Requires integration at the cerebral cortex Can be created (Cat example)
This is the basic contractile unit of a muscle fibre
Sarcomere
This organelle contains and releases calcium
Sarcoplasmic Reticullum
This ATPase determines how quickly a muscle relaxes after contraction
Sarcoplasmic reticullum ATPase
What must occur for a muscle to return to its relaxed state
Sarcoplasmic reticulum must suck up calcium in order to go back from contraction
What are reflexive movements
Sensory input (vision, vestibular, muscle) Can be modulated by higher brain centers Involved in posture
Sprint or strength training causes what kind of shift in fiber types
Shift from type IIx to type IIa
Which is a slow twitch neuron and which is a fast twitch neuron
Slow = yellow Fast = white
During the cross-bride cycle, these two steps must occur before myosin beinds to actin
Splitting of ATP and binding of calcium to troponin
When does summation occur
Summation occurs when a stimulus is delivered to a muscle before it has time to completely relax. This is caused when more calcium is released from the Sarcoplasmic Reticulum. The calcium will bind to additional troponin and this causes more tropomyosin to be lifted off of actin, allowing myosin to form cross-bridges.
This term is used to describe the highest level of force output possible by a muscle. It is acheieved during high frequency stimulation
Tetenous
What is the "Central Pattern Generator (CPG)"
The CPG is a neural network in the lower part of the spinal cord that is thought to control locomotion The central pattern generator Can control walking without input from the brain or reflexes
What is the CNS?
The central nervous system refers to your brain and spinal cord
What is phosphocreatine
The main fuel source when performing strength-training exercise with low reps + high load
What is cross-education
The increase in strength of the untrained contralateral limb after unilateral training. If you strength train one limb, the increase in strength will cross-over to opposite homologous limb.
Why is a larger muscle able to produce more force than a smaller muscle
The larger the muscle, the greater the amount of actin and myosin you have. Actin and Myosin allow you to contract more bridges. Contractile proteins increase with strength training and thus more cross-bridging. More cross-bridging = more force generated
Which protein has the greatest influence on the speed of muscle contraction?
The myosin heavy chain because it contains ATPase activity
What is an axon
The part of a neuron that releases acetylcholine leading to a muscle contraction
How would EMG mean absolute value and median frequency differ between a person with mostly fast twitch motor units versus a person with mostly slow twitch motor units during an exercise where they are required to hold their maximal isometric contraction for 20 seconds?
The person with more fast twitch would see a greater decrease in the mean absolute value and median frequency. The person with more slow-twitch would show less change in MAV and MDF over the 20s contraction because it starts with lower.
Where is Calcium stored inside the muscle fiber?
The sarcoplasmic reticulum
How do you think muscle fibre type changes from birth to the time a toddler learns to walk?
They switch from fast twitch to slow twitch
Creatine kinase is an enzyme that is usually found in your muscle fibres. After an intense bout of exercise creatine kinase levels in the blood are often elevated. What does this indicate?
This indicates that there has been some recent muscle damage. The muscle tears from over exercise and training. Results that peak and then begin to drop indicate that new muscle damage has diminished, while increasing and persistent elevations suggest continued damage.
Which muscles would have the greater number of motor units? Ones with fine or gross movements
Those involved in gross movements like walking
Which of the following would occur first during muscle contraction? Transmission of an action potential down the t-tubule Binding of myosin with actin Release of calcium from the sarcoplasmic reticulum Lifting of tropomyosin off actin
Transmission of an action potential down the t-tubule
This regulatory protein blocks myosin from binding to action
Tropomyosin
What is a regulatory Protein
Tropomyosin and Troponin Regulate whether or not myosin and actin form cross-bridges
Aside from myosin and actin, what other proteins would increase in a muscle as a result of strength training to result in an increase in strength?
Troponin, and sarcoplasmic reticulum ** The more calcium you release, the more troponin
True or False? The fiber types an individual possesses is determined by genetics and cannot be changed
True that an individual possesses fiber types determined by gentics but false that they cant be changed. They can be changed with training.
True or False: You can use your higher brain centres to override the Golgi tendon organ inhibition of motor neurons.
True, You can adjust it with higher brain activity
True or False: Isometric contractions allow you to generate more force than concentric contractions
True, because it is a slower contraction which leaves time for more crossbridges
True of False? Strength training (with moderate to high repetitions) leads to a conversion of fast fibers to slow fibers
True, mainly from Type IIx to type IIa
What are the 4 myosin heavy chains in the order of slowest contracting to fastest contracting
Type I Type IIa Type IIx (fastest in humans) Type IIb (fastest in animals)
Which fiber type is a genetically-elite marathon runner likely to have?
Type I, because they are slow twitch
What type of myosin heavy chains (MHC) are found in the following muscle fibre types?
Type I: MHC I Type Ic: mostly MHC I, some IIa Type IIc: mostly MHC IIa and MHC I Type IIa: MHC IIa Type IIax: MHC IIa and IIx Type IIx MHC IIx
Which fiber types are not found in Human Muscle?
Type IIb
Which muscle fiber types would allow for the fastest speed of contraction?
Type IIb in animals and Tyle IIx in humans
This fibre type is almost completely absent in well-trained endurance atheletes
Type IIx
Who do you think had the greatest increase in muscle mass and why?
Unilaterally, because of the amount of stress being placed on it. With Bilateral, you have stress spread out throughout both legs
What are rhythmic movements
Voluntary and reflex Initiated by cerebral cortex Sustained without input from brain An example is walking
What is bilateral deficit
When the sum of unilateral strength is greater than bilateral strength
Median frequency decreases as a muscle becomes fatigued because...
When you recruit a muscle, you have a mix of slow twitch and fast twitch. Fast twitch become fatigued and then you are just left with slow twitch fibres but have lower fire frequency.
Can excessive stretching ruin a workout?
Yes
What is one advantage to training with eccentric contractions?
You can generate greater hypertrophy and most forceful, increase in strength and power. Allows you to train for movement patterns used in many sports
A motor neuron and all the muscle fibres it innervates
a motor unit
Which of the following would enhance force development: A) activation of agonist muscles B) Inhibition of antagonist muscles C) Inhibition of the Golgi Tendon Organ reflex D) All of the above
all of the above
Why does ability to generate force decrease as velocity of contraction increases?
because myosin is sliding past actin too quickly and therefore cannot form strong cross bridges. -myosin has more time to form a crossbridge with actin when speed is decreases
Why will a thicker axon allow a faster action potential conduction velocity
because there is less resistance to flow of electrical current
This part of the nervous system is involved in coordination and fine-tuning of movements
cerebellum
This occurs in excitable tissue when sodium enters
depolarization
This is the most forceful type of muscle contraction
eccentric
Too much potassium leaving the muscle fiber after a contraction
hyperpolarization
Activation of the muscle spindle does this to the antagonist
inhibits
Depletion of glycogen does what
limits your ability to complete a marathon
This receptor is very active during a muscle cramp
muscle spindle
Tetanus is the prolonged contraction of a muscle caused by rapidly repeated stimuli. Why does this occur
occurs when troponin is saturated with calcium occurs with high frequency stimulation of the muscle
These receptors allow you to detect the position of your limbs
proprioceptors
Too much of this type of exercise may inhibit subsequent power performance
stretching
When does cross-education have a stronger effect
stronger effect when dominant limb is trained, and transferred to non-dominant limb
Cross education occurs mainly in this direction in right-handed individuals
whatever your dominant hand is, dominant to non-dominant
