Podcast
Questions and Answers
Which physical abilities are highly modifiable through training?
Which physical abilities are highly modifiable through training?
What is the main characteristic of complex reaction time?
What is the main characteristic of complex reaction time?
Which of the following is an example of a discrete movement?
Which of the following is an example of a discrete movement?
Which of the following statements regarding physical abilities is true?
Which of the following statements regarding physical abilities is true?
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What distinguishes continuous movements from discrete movements?
What distinguishes continuous movements from discrete movements?
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Which of the following is an example of a serial movement?
Which of the following is an example of a serial movement?
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In terms of physical abilities, which aspect is largely determined by genetics?
In terms of physical abilities, which aspect is largely determined by genetics?
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What role does the nervous system play in regulating muscle properties?
What role does the nervous system play in regulating muscle properties?
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Which of the following describes the mechanical property of contractility?
Which of the following describes the mechanical property of contractility?
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What are the elements that make up the elastic properties of muscle?
What are the elements that make up the elastic properties of muscle?
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During an eccentric contraction, what occurs in relation to energy?
During an eccentric contraction, what occurs in relation to energy?
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What is the significance of the force-length relationship in muscle physiology?
What is the significance of the force-length relationship in muscle physiology?
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Which of the following statements is true about the mechanical properties of skeletal muscles?
Which of the following statements is true about the mechanical properties of skeletal muscles?
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What is the primary function of tendons in relation to muscles?
What is the primary function of tendons in relation to muscles?
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Which of the following properties primarily allows muscles to stretch?
Which of the following properties primarily allows muscles to stretch?
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Which element in the simplified muscle model is responsible for producing force?
Which element in the simplified muscle model is responsible for producing force?
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What is the term for the length at which the greatest active force occurs in a muscle?
What is the term for the length at which the greatest active force occurs in a muscle?
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Which of the following factors can lead to a decrease in active force production in muscle?
Which of the following factors can lead to a decrease in active force production in muscle?
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What type of force is produced by active cross-bridges during muscle contraction?
What type of force is produced by active cross-bridges during muscle contraction?
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At what muscle length does passive force begin to develop?
At what muscle length does passive force begin to develop?
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What happens to active force when the muscle is overstretched?
What happens to active force when the muscle is overstretched?
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Which statement accurately describes total force in a muscle?
Which statement accurately describes total force in a muscle?
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What occurs when muscle is maintained at its optimal length (Lo)?
What occurs when muscle is maintained at its optimal length (Lo)?
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During which condition does the muscle exhibit resistance to stretch?
During which condition does the muscle exhibit resistance to stretch?
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What is the primary reason for lower active force at short muscle lengths?
What is the primary reason for lower active force at short muscle lengths?
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Which force is responsible for muscle resistance to stretch when the muscle is relaxed?
Which force is responsible for muscle resistance to stretch when the muscle is relaxed?
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What is the primary effect of the eccentric phase in the stretch-shorten cycle?
What is the primary effect of the eccentric phase in the stretch-shorten cycle?
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Which factor is thought to contribute to the mechanism of the stretch-shorten cycle?
Which factor is thought to contribute to the mechanism of the stretch-shorten cycle?
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What is the role of stiffness in the stretch-shorten cycle?
What is the role of stiffness in the stretch-shorten cycle?
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Which training type specifically may alter muscle-tendon properties related to the stretch-shorten cycle?
Which training type specifically may alter muscle-tendon properties related to the stretch-shorten cycle?
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What is a potential long-term effect of flexibility training on the stretch-shorten cycle?
What is a potential long-term effect of flexibility training on the stretch-shorten cycle?
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What occurs during an eccentric contraction?
What occurs during an eccentric contraction?
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What is the main role of the quadriceps during a counter-movement jump?
What is the main role of the quadriceps during a counter-movement jump?
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What defines a concentric contraction?
What defines a concentric contraction?
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What is the stretch-shorten cycle (SSC) enhanced by?
What is the stretch-shorten cycle (SSC) enhanced by?
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What is the preload effect in the context of muscle contractions?
What is the preload effect in the context of muscle contractions?
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Which of these movements is an example of a concentric contraction?
Which of these movements is an example of a concentric contraction?
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During the descent of a counter-movement jump, what process primarily occurs?
During the descent of a counter-movement jump, what process primarily occurs?
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Which statement about eccentric contractions is false?
Which statement about eccentric contractions is false?
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Why is more force produced during the stretch-shorten cycle?
Why is more force produced during the stretch-shorten cycle?
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In the context of muscle contraction, what characterizes an eccentric-concentric contraction?
In the context of muscle contraction, what characterizes an eccentric-concentric contraction?
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Study Notes
Motor Learning - Week 4
- Course: PHYL 4518
- Instructor: Zoe Chan, PhD
- Date: F2024 - Week 4
Review of In-Class Quiz - Physical Abilities
- Highly modifiable through training (e.g., muscle strength, muscle mass, flexibility, maximal oxygen uptake)
- Largely genetic
- Not to be confused with static vs. dynamic exercises
Review of In-Class Quiz - Static Abilities
- Static abilities have limited potential to change (e.g., muscle fiber type, height, lung size)
Review of In-Class Quiz - Movement Continuity
- Throwing a punch: Discrete
- Steering a car: Serial
- Playing a piano composition: Continuous
- Triple jump: Discrete (approach run,hop, step, jump)
- Running: Continuous
Review of In-Class Quiz - World Records
- Triple jump world record (men): 18.29 m (Edwards, 1995)
- Long jump world record: 8.95 m
Review of In-Class Quiz - Simple vs. Complex Reaction Time
- Simple: One stimulus, one response
- Complex (choice): Two or more stimuli, specific responses
- Complex (discrimination): Two or more stimuli, one paired with each response
Review of Relative Age Effect
- Preference for selecting athletes born earlier in the year
- Example: January 15, 2024 selection for 9-year-olds
- Athletes born on January 16th, 2014 were 9 years, 11 months, and 364 days old
- Athletes born on January 15th, 2015 were 9 years, 0 months, and 0 days old
- Example: age cut-off on April 1, 2014 selection to determine age advantage, athletes born earlier in the year have advantage
Unit 3: Peripheral Neuromuscular Mechanisms in Executing Movement
- Understanding basic mechanical properties of muscles (how they contribute to and enhance movement)
- Description of central and peripheral nervous system, and their contribution to movement
- Explanation of neuron functions and communication systems
- Description of motor unit physiology and organization
Muscle Properties - Mechanical Properties
-
Extensibility: Stretch and recoil from stretch
- Muscle tissue
- Connective tissues (running throughout the muscle tissue)
- Contractility: Muscle tissue only, shortening to create force
Muscle Properties - Simplified Model
- CE (Contractile element): Produces force
- PE & SE (Elastic element): Parallel (PE) - connective tissues, Serial or series (SE) - tendons - stores and release through recoil
Muscle Properties - Stretch and Recoil
- Depend on shortening/lengthening velocity, tissue length/thickness, and health of the tissue
- Nervous system regulates mechanical properties (stiffness, force absorption, and recoil)
- By changing timing and amount of muscle contraction
- Changes the flow of forces or energy
Muscle Properties - External Forces & Muscle Work
- External forces: body weight
- Stretch muscle-tendon complex
- EE - stores the force
- Reduced muscle work
Muscle Properties - Concentric Contraction
- Muscle contracts, building up force, transfer stored in tendon and releases rapidly
- Activities: jumping, acceleration, incline running
Muscle Properties - Eccentric Contraction
- External force stretches tendon, energy stored in EE, transferred to muscle, muscle absorbs force
- Activities: decline running, deceleration, landing
Force-Length Relationship
- Passive force: Resistance of relaxed muscle to stretch (EE)
- Resting length: Length at which passive force begins to develop
- Optimal length (lo): Length at which greatest active force occurs
- Active force: Produced by active cross-bridges during contraction (CE)
- Total force: Active + passive force
Stretch-Shorten Cycle (SSC)
-
Concentric vs. eccentric contraction:
- Concentric: muscle shortens, force generated
- Eccentric: muscle lengthens, stretches, force less that resistance
- Eccentric-concentric contraction: Counter-movement jump (starts from standing, squat, downwards movement using quadriceps and knee extension)
-
Mechanism of SSC:
- Preload effect: more time for contraction, where muscle already activated
- Buildup of stored elastic energy (elastic tissues) in the eccentric phase, is released at recoil during concentric phase
- Optimal length – muscle stretched at eccentric phase
- Excite reflex mechanism
Stiff SE (Stretch-Shorten Cycle)
- Stiffer SE = more SSC
- But: Stiff CE
- Same force during ECC (eccentric contraction)
- Similar energy return during CON (concentric contraction)
Exercise Training & Neuromechanics
- Flexibility training (static stretching): May alter muscle-tendon properties, acute flexibility exercises, and transient increases in joint ROM
- Strength training: Increasing muscle-tendon stiffness, increasing tissue thickness, and increasing tissue density
- Plyometric training: Increasing stretch force, targeting SSC, high-effort power training (forceful eccentric followed by explosive rapid reversal concentric).
Flexibility Training
- Data on flexibility training and injury prevention is varied and inconclusive
- Little/inconclusive evidence that stretching helps reduce muscle injuries or muscle soreness
- Used as a tool to maintain muscle health, particularly in aging populations
Strength Training
- Resistance training may increase muscle-tendon stiffness by increasing tissue thickness (hypertrophy) and increasing tissue density.
Plyometric Training
- Increasing to stretch force targeting SSC and high-effort power training
- Light-load weight-lifting and maximal speed of concentric phases
- Plyometric training increase muscles stiffness, maximize recoil (energy return), develop neural coordination
Nervous System Organization
- Central nervous system (CNS): Brain and spinal cord (integration and command center for entire nervous system)
- Peripheral nervous system (PNS): Branches out from CNS, Motor (efferent) & Sensory (afferent) neurons.
- Somatic: Skeletal muscle (voluntary movement)
- Autonomic: Smooth muscle, and glands (involuntary movement) – sympathetic, parasympathetic
Neuron Structure
- Cell bodies (soma)
- Dendrites (signal in)
- Axons (signal out)
- Neurons classified as: sensory (afferent), motor (efferent), interneurons
Action Potentials
- Bioelectric signal (AP)
- Spread through synapses, Neurons communicate via changes in charge across membrane
- Sodium (Na+) and potassium (K+) ions.
- Depolarization, Repolarization, Hyperpolarization, and Overshoot, and closing of K+ channels
- AP moves along neuron
Neuron Function
- Neurotransmitters released from presynaptic neuron (may depolarize postsynaptic neuro, generating an excitatory postsynaptic potential (EPSP)
- Other neurotransmitters can block depolarization which generates an inhibitory postsynaptic potential (IPSP)
- Multiple EPSPs (summation- temporal or spatial) in postsynaptic neuron to generate AP (action potential)
- Ratio of EPSPs to IPSPs
Motor Neurons
- Axons branch off
- Motor unit (MU): one motor neuron activates a number of muscle fibers
- Innervation ratio - controlled by one neuron
Motor Unit
- Spread out within the muscle
- Muscles distribute force over large areas, "smoother" contractions and even force
- May help delay fatigue. Active and inactive fibers sharing metabolites and capillaries.
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Description
Test your knowledge on motor learning concepts covered in Week 4 of PHYL 4518. This quiz reviews physical and static abilities, movement continuity, world records in jumping events, and types of reaction time. Enhance your understanding of how various factors influence motor performance.
