Ex Phys - Text #2

Which principle of training are these aspects describing? "What improvements in arm work and leg work from before to after training, are made for the arm-training group and leg-training group? Improvements are a decrease in ventilation equation (VE/VO2) All forms of aerobic exercise improve heart"

Specificity

True or false: Cross-sectional area of a person tells you how strong they are

True

True or false: For a given MET, some groups may be working at greater relative level of VO2max, ex: older adults, cardiopulmonary disease

True

True or false: GTO's are extremely sensitive - it can detect change in tension in a single muscle fiber

True

True or false: Motor unit recruitment and rate coding can occur concurrently depending on demands of the task

True

True or false: Muscles and tendons, highly adaptable tissues, respond favorably to chronic changes in loading independent of age or gender

True

What causes muscle tone?

Sustained muscle contraction of type II afferents

True or false: Eccentric muscle actions induce greater DOMS than concentric-only or isometric actions, particularly in older adults

True Existing muscle damage or soreness from previous activity does not exacerbate subsequent muscle damage or impair the repair process the body initiates a series of adaptive cellular events to unaccustomed exercise that produces DOMS

What are the seven ACSM CVD risk factors?

1) Age: Men ≥ 45 y; Women ≥ 55 y 2) Cigarette smoking 3) Sedentary (no moderate activity ≥ 3 days/week) 4) Obesity (BMI ≥ 30) 5) Hypertension (BP > 130/80) 6) Dyslipidemia (bad cholesterol) 7) Impaired glucose control

Read other side for the summary of neural adaptations to exercise pt. 2

1) Alteration in motor unit recruitment and firing pattern helps to explain rapid rapid improvements in strength early in training 2) Later improvements in training are largely due to muscle hypertrophy 3) Fatigue occurs from disruption in the chain of events between CNS and the muscle fiber

What are the four benefits to core training?

1) Appropriate distribution of forces 2) Optimal control and efficiency of movements 3) Adequate absorption of ground-impact forces 4) Absence of excessive compressive, translation, and shearing forces across kinetic-chain joints

What are the three metabolic fundamental muscle fiber properties?

1) Fast/slow myosin (F or S) 2) High oxidative capacity (O) = IIa 3) High glycolytic capacity (G) SO (most resistant to fatigue), FOG, FG

What are six factors that modify expressions of human strength?

1) Greater efficiency in neural recruitment patterns 2) Increased motor neuron excitability 3) Increased central nervous system activation 4) Improved motor unit synchronization and increased firing rates 5) Lowering of neural inhibitory reflexes 6) Inhibition of Golgi tendon organs

What are seven factors that can produce DOMS?

1) Minute tears in muscle tissue or damage to its contractile components 2) Osmotic pressure changes 3) Muscle spasms 4) Overstretching and tearing of portions of the muscles connective tissue harness 5) Acute inflammation 6) Alteration in the cells calcium regulation 7) Combination of above factors

Read other side for the summary of neural adaptations to exercise pt. 1

1) Neural control mechanisms in CNS regulate movement 2) Motor unit represents the functional unit of movement 3) Motor units classify into three types depending on speed of muscle action, force generated, and fatigability 4) Motor unit types: • Fast twitch, high force, fast fatigue • Fast twitch, moderate force, fatigue resistant • Slow twitch, low force, fatigue resistance

What are the two types of muscle soreness?

1) Occurs following extended layoffs or with unaccustomed exercise 2) Appears later and can last for 3-4 days; termed Delayed Onset Soreness or DOMS

What are the five steps to rate code?

1) Single action potential: muscle twitch 2) Series of action potentials: muscle does not have a time to relax 3) Results in additive force generated: summation 4) Plateau in force: any further ↑ in AP frequency, will not ↑ force 5) Plateau is known as tetanus: smooth muscular movement

What are the seven strength testing considerations?

1) Standardize instructions prior to testing • Pt standardizes for MMT, because we are trying to match THEIR effort 2) Ensure uniformity in duration/intensity of warm up 3) Provide adequate practice prior to testing to minimize "learning" effect 4) Ensure consistency among subjects in angle of limb measurement and/or body position on device 5) Predetermine a minimum number of trials 6) Select test measures with high reproducibility 7) Recognize individual differences in body size and composition when evaluating strength

What are the steps to the stretch reflex?

1) Stretch of muscle (e.g., quads) 2) Stimulates muscle spindles in quads 3) Activates afferents (Ia fibers) 4) Afferents carry impulse to spinal cord and synapse with alpha motor neurons (efferents) 5) Alpha motor neurons synapse on extrafusal fibers of muscle causing contraction (i.e., extension of knee)

Your patient increased his intensity by 7 ml/kg/minute, how many METs is that?

2, because it is 3.5 ml/kg/min for 1 MET

How do you train to become stronger?

A muscle strengthens when trained near its current maximum force-generating capacity Overload intensity, not type of exercise that applies overload, governs strength improvements Types of overload applications: • Progressive-resistance weight training • Isometric training • Isokinetic training

What is active tension dependent upon and what are the three regions of the Length-Tension curve?

Active tension depends on the length of the sarcomere 3 regions of Length-Tension (L-T) curve: 1) Ascending 2) Plateau 3) Descending

What is this describing? "Alpha motor neurons innervate striated muscle (extrafusal fibers) and cause the muscle contractions. Constitute "final common pathway" in motor processing (Charles Sherrington)"

Anterior motor neurons

What are some gender differences in muscle strength?

Approaches to determine if true gender difference exists in muscle strength: 1) Muscle's CSA 2) Absolute basis as total force exerted 3) Architectural characteristics 4) Relative strength indexed to estimates of body composition via allometric scaling

What region of the L-T curve is this describing? "At very short lengths (around 1.0 µm and below), little to no force. From 1.0-1.6 µm, increase in cross-bridge formation, but some overlap of actin. Between 1.6 and 2.0 µm, overlap of actin is less"

Ascending limb Muscle is already contracted

What is this describing? "Distal segment bears body weight or part of body weight. Activates both agonist and antagonist muscles about a joint, including other muscle groups along the kinetic chain. Often considered more functional than exercises where distal segment is non-weight bearing as in conventional weight-lifting"

Body Weight-Loaded (CKC) training

Which muscle strength measurement tool is this describing? "Increasing force on cable depresses riser over which the cable passes. Deflects pointer and indicates a subject's strength score. Measure muscle force in a static or isometric muscle action that elicits little or no change in the muscle's external length"

Cable tensiometry When documenting, put angle joint and where you placed the weight. Ex: biceps @ 90°, weight at wrist OR weight in middle of forearm

Why is the treadmill a good spy?

Can hear stepping, excess weight on one foot/not appropriate eccentric contraction

What are the three types of motor units and what are they classified by?

Classified by twitch properties, fatigue index 1) Slow (S) = slow, constant 2) Fast fatigue resistant (FFR) 3) Fast fatigable (FF) = sprinters Match with fiber types

What are the gender differences in terms of absolute basis as total force exerted (normal adults)?

Comparisons of muscular strength on an absolute score basis (i.e., total force in lbs or kg) indicate that men possess considerably greater strength than women for all muscle groups Women score about 50% lower than men for upper body strength and about 30% lower for leg strength Differences in maximum weight lifted between men and women in same body mass categories. Women in lower weight class are able to lift the highest percentage as compared to men

Which muscle strength measurement tool is this describing? "Force platforms measure the external application of muscle force by a limb, as in jumping. Other electromechanical devices assess forces generated during all phases of an activity (e.g., cycling) or primarily arm (supine bench press) or leg (leg press) movements"

Computer-assisted, electromechanical, and isokinetic methods Good for squatting, post-surgery and weight-bearing on the non-operated leg

What is this describing? "The core represents a four-sided muscular frame with four components: • Abdominal muscles in front • Paraspinals and gluteals in back • Diaphragm at the top • Pelvic floor and hip girdle musculature frames the bottom Includes 29 pairs of muscles (planks) that hold trunk steady, and balances and stabilizes surrounding bony structures"

Core training

What are the effects of detraining on muscle?

Data on muscle strength decrements and associated factors with cessation of resistance training conclude: • Discontinuing training for 2 weeks caused male power lifters to lose 12% of the isokinetic eccentric muscle strength and 6.4% of their type II muscle fiber area, without loss in type I fiber area → Reducing training frequency to 1-2 weekly sessions provides sufficient stimulus to maintain training-induced strength gains

What region of the L-T curve is this describing? "Number of cross-bridges decreases. Greater than 3.2 µm, no overlap of actin and myosin"

Descending limb Lengthened muscle

Which muscle action is this describing? "Produces movement of bones (i.e., upper or lower limb or trunk). Concentric: occurs when muscle shortens and joint movement occurs as tension develops. Eccentric: occurs when external resistance exceeds muscle force and muscle lengthens while developing tension (can cause more muscle lesions because myosin and actin are being pulled apart)"

Dynamic muscle action

Which muscle strength measurement tool is this describing? "External force applied to dynamometer compresses a steel spring and moves a pointer. The force required to move the pointer a given distance determines applied external force"

Dynamometry

What is EMG and what are the advantages and disadvantages?

EMG: measures activity of muscle Advantages: • Measure activity of single muscles • Measure functional tasks Disadvantages: • Dependent on many factors - temp, interelectrode distance, skin impedance, etc. • EMG dependent on tension, length, fatigue

What is this describing? "Excitatory, depolarizing graded potentials - membrane potential - threshold"

EPSP: Excitatory post synaptic potentials

What are some learning factors that affect strength measures?

Early gains in strength with resistance training result largely from neural factors instead of structural changes within muscle

What is neuromuscular fatigue and what are the differences between central and peripheral fatigue?

Exercise induced reduction in ability of muscle to maintain power/force Central fatigue: • Proximal to motor neuron • Hypoglycemia affects cortical motor neurons • Sense of effort Peripheral fatigue: • Involves motor unit • ↓ Ach at NMJ • Exhaustion of muscle energy supply • ↓ ATP • ↑ Lactate and H+ ions = ↓ pH • K+ efflux impairs muscle contraction

How might endurance training, strength training, and muscular inactivity cause a shift in myosin isoforms?

Exercise training = ↓ type IIx and ↑ type IIa

True or false: Each motor unit consists of muscle fibers that are all the different fiber types (type I, type IIa, or type IIx)

False, it should say... Each motor unit consists of muscle fibers that are all the same fiber type (type I, type IIa, and type IIx) When activated, all muscle fibers in a motor unit contract simultaneously - all or none principle

True or false: muscle fiber composition does not correlate with maximal oxygen consumption

False, it should say... Muscle fiber composition correlates with maximal oxygen consumption

True or false: Properties of slow & fast muscle fibers cannot be reversed

False, it should say... Properties of slow & fast muscle fibers can be reversed • When innervation to these fibers are surgically altered • So that slow fibers were innervated by fast motor neurons and vice versa Chronic stimulation changes properties of muscle fibers → pattern of neural activity influences muscle fiber behavior

True or false: Visceral fat is reduced by endurance training

False, it should say.... Visceral fat is reduced by resistance training

Which motor unit is this describing? "Axon size: largest. Highest activation threshold. Twitch characteristics: contraction velocity = fast; tension = high. Energy use = anaerobic glycolysis. Greater number of fibers in motor unit and larger fibers"

Fast fatigable (FF) - Fast glycolytic (FG fiber) - Type IIx

What class of motor unit is this describing? "Large motor neuron. Larger pale muscle fiber. Fatigue quickly. Sparse mitochondria. Large force"

Fast fatigable MU (type IIx)

What class of motor unit is this describing? "Intermediate sized motor neurons. Moderate force. More resistant to fatigue"

Fast fatigue-resistant MU (type IIa)

Which motor unit is this describing? "Axon size: larger. Higher activation threshold. Twitch characteristics: contraction velocity = faster; tension = higher. Energy use = oxidative phosphorylation and anaerobic glycolysis"

Fast, Fatigue resistant (FFR motor unit) - Fast Oxidative Glycolytic (FOG muscle fiber) - Type IIA

Test question: Which of the six factors that modify human strength is non-modifiable?

Genetics

What are six factors that modify human strength?

Genetics Nervous system activation Environmental factors Endocrine influences Nutritional status Physical activity

What are the gender differences in muscle's CSA?

Human skeletal muscle regardless of gender generates a maximal force between 16 and 30 newtons (N) per square centimeter of muscle cross section In the body, force-output capacity varies depending on the arrangement of the bony levers and muscle architecture Variability of strength of men and women related to muscle's total CSA (image) (Judo = Japanese martial arts)

What is this describing? "Increase in muscular tension (force) with training provides main stimulus to initiate muscle growth. Reflects biologic adaptation to increased workload independent of gender/age. Overload training enlarges individual fibers with subsequent muscle growth. Changes in muscle size become detectable after at least 3 weeks of training. Remodeling of muscle architecture precedes gains in muscle cross-sectional area"

Hypertrophy

What is this describing? "Inhibitory, hyperpolarizing graded potentials - membrane potential away from threshold"

IPSP: Inhibitory post synaptic potentials

What are some neural and muscular adaptations to exericse?

Increase in strength • Rapid improvements in NM function (early) • Gradual improvements in hypertrophy (later) Once neural adaptations are maximized further, increases in hypertrophy occur Strength and hypertrophy plateau at the same time

What does dynamic stretch help with?

Increase ROM with active muscle (opposite to muscle being stretched) contraction Causes reciprocal inhibition of stretched muscle Better than static stretch (avoids the caveats)

Force of muscle action varies from slight to maximal via what two things?

Increased number of motor units recruited: • Muscle generates considerable force when all its motor units activate Increased frequency of motor unit discharge: • Repetitive stimuli that reach a muscle before it relaxes and increases the total tension

What is this describing? "Each muscle fiber generally receives input from only 1 motor neuron; a motor neuron may innervate many muscle fibers. __________ _______ refers to the ratio of muscle fibers innervated by 1 motor neuron. ________ _______ determines size of the motor unit. Differs across muscle groups: • Soleus (posture) - 1:180 • Gastrocnemius (force generation) - 1:2000 • Extraocular eye muscles (fine movements) - 1:3"

Innervation ratio

What is this describing? "Contains speed-controlling mechanism that accelerates to a present, constant velocity with force application. Once attaining speed, isokinetic loading mechanism adjusts automatically to provide counterforce to variations in force generated by muscle as movement continues throughout the "strength curve". Maximum force (or any percentage of max effort) generates throughout the full range of motion (ROM) at a pre-established velocity of limb movement"

Isokinetic "constant velocity" dynamometer

What are two other factors that determine force?

Length-tension relationship: • Optimal length: between 100-120% of muscle's resting length • Allows for maximum overlap of cross bridges - optimal force Force-velocity relationship: • Slower muscle shortening allows for greater force production • At faster velocities, cross-bridges cannot keep up with sarcomere

What are the corresponding numbers (METS) for the items listed below for CDC/ACSM classification of physical activity? Light physical activity Moderate Vigorous

Light physical activity: <3 METs Moderate: 3-6 METs (40-60% VO2max) Vigorous: >6 METs (>60% VO2max)

What is this describing? "Increased body mass = more energy. More accurately expressed relative to body mass: 1 MET = 3.5 ml/kg/min. Energy expenditure increases with: intensity and duration of activity. Account for gender, height, weight, and age (RMR)"

MET

What are the gender differences in terms of allometric scaling?

Mathematical procedure to establish a proper relationship between a body size variable and physiologic variable or performance measure Provides a statistical adjustment to evaluate relative contribution of diverse independent variables on dependent measure of interest

What are the fiber type differences amongst athletic groups?

Men, women, and children on average possess 45-55% slow-twitch fibers in arm and leg muscles Fast-twitch fibers distribute equally between type IIa and type IIx subdivisions Although no gender differences exist in fiber distribution, large interindividual variation occurs Trend in one's muscle fiber type distribution remains consistent among the body's major muscle groups Endurance athletes possess predominately slow-twitch fibers, while fast-twitch fibers predominate for elite sprint athletes Performance success depends not only on muscle fiber composition, but on a blending of many physiologic, biochemical, neurologic, and biomechanical "support systems" Larger muscle fibers in male athletes along with a larger total muscle mass are principal gender differences in muscle morphology (fat = ↓ contractile property)

What are the American Heart Associations/ACSM's recommendations for activity for moderate intensity aerobic exercise and vigorous intensity exercise?

Moderate Intensity Aerobic: • 40-60% reserve (VO2max or HR) • 30 minutes, 5x per week OR Vigorous intensity: • >60% reserve • 20 minutes, 3 times per week

What are the minimum guidelines for activity for moderate and vigorous activity in combination? What are the two additional benefits?

Moderate in 10 minute episodes Muscular strength and endurance training 2x per week Additional benefits: • >300 min/week moderate • >150 min/week vigorous

Is the stretch reflex monosynaptic or disynaptic?

Monosynaptic

What is this describing? "Functional unit of movement. Term coined by Sherrington. Consists of anterior motor neuron and specific muscle fibers it innervates. Individual motor axons branch within muscles to contact fibers distributed over a wide area. Allows for even spread of contractile force. Protects muscle from becoming dysfunctional when one motor neuron dies out"

Motor unit

What is this describing? "Properties of α motor neurons scale proportionally with the size of motor units. Most skeletal muscles possess different fiber phenotypes. Variations of muscle fiber properties combine with variations of α motor neuron properties determine physiological function of motor units"

Motor unit plasticity

What is this describing? "The increase in strength achieved during early phases (8-10 weeks of training) of exercise is due to changes in neural mechanisms. Neural adaptations include: improved synchronization of motor unit firing, and improved recruitment"

Motor unit plasticity

What is the difference between a motor unit and a motor neuron pool?

Motor unit: • Represents an alpha-motor neuron and the fibers it innervates Motor neuron pool: • Motor neurons are clustered in columnar, spinal nuclei called motor neuron pools • Represents all the alpha-motor neurons that innervate one muscle • One-to-one relationship between a muscle and a motor neuron pool

What is this describing? "Skeletal muscles represent dynamic tissues; they do not remain fixed throughout life. Muscle fibers undergo regeneration and remodeling to alter their phenotypic profile. Activation of muscle via specific types and intensities of long-term use stimulates otherwise dormant myogenic stem cells situated under a muscle fibers basement membrane; these proliferate and differentiate to form new fibers. Specific training can transform muscle fiber-type"

Muscle cell remodeling

What does static stretch help with?

Muscle spindle becomes habituated to new length and reduces its signaling: known as stretch relaxation Allows for greater ROM at a joint - greater stretch of muscle and connective tissue Comes with caveats: • Compromised L-T (length-tension) relationship • Desensitization of muscle spindle produces lesser reflexive muscle force

Muscle spindle consists of 8-10 intrafusal fibers ___________ to muscle fibers. Muscle spindle __________ when muscle is stretched. This causes _________ _________ ___________ and _________ ________- Prevents overstretching of muscle

Muscle spindle consists of 8-10 intrafusal fibers parallel to muscle fibers. Muscle spindle stretches when muscle is stretched. This causes reflexive agonist contraction and antagonist relaxation. Prevents overstretching of muscle

What is muscle strength and what can it be measured by?

Muscle strength represents the maximum force or tension output generated by a muscle or related muscle groups Can be measured by: • Cable tensiometry • Dynamometry • One-repetition maximum • Computer-assisted force and power output determinations

What are muscle spindle's sensitive to?

Muscle stretch/lengthening

Which muscle strength measurement tool is this describing? "Maximum amount of weight lifted one time using proper form during a standard weightlifting movement • Difficult to estimate initial weight • Weight progressively added until person reaches maximum lift capacity → Weight increments range between 1-1.5 kg → Rest interval between lifts important"

One-repetition maximum

What are three things that EMG can tell you about?

Onset and offset: • Delay between onset and movement Amplitude - measure of relative force: • Comparing individuals = normalization • Reliability is low Frequency: • Frequency decreases with fatigue

Which principle of training are these aspects describing? "Activity - specific for training response. Intensity: greater than normal"

Overload

What are the four principles of training?

Overload Specificity Individual differences Reversibility

Which factor of muscular strength is this describing? "Adaptive alterations in nervous system function that elevate motor neuron output account for rapid and large strength increases early in training, without increases in muscle size and cross-sectional area"

Physiologic/neural factors

What region of the L-T curve is this describing? "Force is nearly constant. Maximal overlap between actin and myosin. Maximum isometric force. Resting length"

Plateau region (active muscle contraction)

Look at image for example of individual differences between player A and player B?

Player B might have worse conditioning due to his heart rate being higher OR He might be a forward and is running around the court much more However, since his heart rate already starts higher at the beginning, we would assume the conditioning is the correct assumption

What is this describing? "Requires various jumps in place or rebound jumping to mobilize inherent stretch-recoil characteristics of skeletal muscle and its modulation via the stretch (myotatic) reflex. Involves rapid stretching followed by muscle-shortening during dynamic movements. When combined with vigorous muscle action, plyometric actions should greatly increase force that overloads muscles, thereby facilitating increases in strength and power"

Plyometric training

What is the most popular strength training method?

Progressive resistance exercise (PRE)

What is this describing? "Muscle twitch: single quick contraction followed by relaxation. Muscle fibers typically receive several stimuli for undergoing contraction. The frequency at which the stimuli reach NMJ: _______ ______. As rate coding increases, muscle fibers do not have time to return to full relaxation after an initial stimulus"

Rate code Rate code = frequency of action potentials

What is an innervation ratio?

Ratio of muscle fibers innervated by 1 motor neuron

What are the gender differences in terms of muscle strength indexed to body composition?

Relative comparisons involve creating a ratio score by dividing strength score (weight lifted) by body composition score (BW, FFM, MCSA, or limb volume or girth) Such ratio scores based on BW or FFM considerably reduce (if not eliminate) the large absolute strength differences usually observed between genders

What are the effects of resistance training?

Resistance training enables easier recruitment or larger, high-threshold motor units Rate coding can increase with resistance training - faster time-to-peak force production Contraction speed is controlled by rate coding, whereas power is more related to motor unit recruitment

Which principle of training is this describing? "Detraining. Both VO2max and muscle mass decrease. Time period: can occur 3 weeks"

Reversibility

What is a Golgi tendon organ? What activates it? What happens when it is activated? What is the net effect?

Sensory receptor at junction of muscle and tendon Active contraction of muscle - activates GTO Activation of GTO - produces a volley in afferent fibers - Ib Activation causes inhibition of agonist (autogenic inhibition) Net effect: reduces period of contraction of muscle. Also known as inverse myotatic reflex

What is this describing? "Considerable plasticity exists for metabolic potential because specific training enhances anaerobic and aerobic energy transfer capacity of both fiber types. Heightened oxidative capacity of fast-twitch fibers with endurance training brings them to a level nearly equal to the aerobic capacity of the slow-twitch fibers of untrained counterparts. Endurance training induces some conversion of type IIx fibers to the more aerobic type IIa fibers. Metabolic characteristics of specific fibers and fiber subdivisions undergo modification within 4-8 weeks of training • Occurs despite lack of dramatic changes in inherent muscle fiber type • Decrease in percentage type IIx and corresponding increase in type IIa fibers denotes prominent and rapid training adaptations"

Significant metabolic adaptations in strength occurring

What class of motor unit is this describing? "Small motor neurons. Small red muscle fibers. Rich capillary bed. Rich in myoglobin and mitochondria. Low force, sustained contraction"

Slow MU (type I)

What does the innervation ratio determine?

Size of motor unit

What is this describing? "Strength of input onto motor neurons determines orderly recruitment of motor units. Motor units with smaller motor neurons are recruited before larger motor units with larger motor neurons. Governed by size of cell body of motor neuron Smaller motor units have lower surface area - low threshold for activation Larger motor units have greater surface area - greater threshold for activation All motor units in a muscle do not fire simultaneously. Extent of number and size of MU recruitment determined by force needs of muscle. Extreme conditions: all MUs could be recruited at the same time"

Size principle

What are the two principles that govern the relationship between motor neuron activity and muscle force?

Size principle Rate code

Which motor unit is this describing? "Axon size: small. Frequencies: low. Twitch characteristics: contraction velocity = slow; tension = low. Energy use = oxidative phosphorylation (↑ resistance to fatigue)"

Slow (S motor unit) - Slow twitch, Oxidative (SO muscle fiber) - Type I

What is the variation in muscle fiber types in whole muscles of sprinters vs endurance runners?

Sprint: type II Endurance: type I

Which muscle action is this describing? "Involves muscle activation without observable change in muscle fiber length. Isometric: occurs when muscle generates force and attempts to shorten but cannot overcome external resistance"

Static muscle action

Total force = what + what? Active tension varies as a _________ of length Passive tension: what is it?

Total force = Active + Passive Active tension varies as a function of length Passive tension: tendons, capsules, ligaments • Lengths greater than the resting length • Connective tissue stretching out

What is this describing? "Contraction of a single motor unit generated by a single action potential"

Twitch

Motor units are classified based on what three things?

Twitch characteristics Force characteristics Fatigability

What are the three types of motor units and are they slow or fast?

Type I: • Slow twitch, low force, and fatigue resistant (oxidative) Type IIa: • Fast twitch, moderate force, and fatigue resistance (oxidative and anaerobic, intermediate) Type IIx: • Fast twitch, high force, and fast fatigue (anaerobic)

Which muscle fibers do resistance exercises target?

Type II

What are the BMI scores for the items listed below? Underweight Normal Overweight Obesity, Class 1 Obesity, Class 2 Obesity, Class 3

Underweight: <18.5 Normal: 18.5-24.9 Overweight: 25-29.9 Obesity, Class 1: 30-34.9 Obesity, Class 2: 35-39.9 Obesity, Class 3: ≥ 40

Are motor units subject to use-dependent plasticity?

Yes

Can the stretch reflex be controlled with training?

Yes

What are the corresponding regions of the sarcomere to the names listed below? Z-line to z-line: ? A-band: ? M-line: ? H-zone: ? I-band: ?

Z-line to z-line: sarcomere length A-band: area of myosin filaments M-line: center of A-band H-zone: thick myosin only I-band: thin actin only

What occurs at the spaces listed below during sarcomere shortening? Z-lines: ? A-band: ? H-zone and I-band: ?

Z-lines: gets closer A-band: stays the same H-zone and I-band: gets smaller

What are five neural adaptations to resistance training?

↑ efficiency in recruitment ↑ motor neuron excitability, CNS drive ↑ Co-ordination between muscles ↑ MU synchronization ↓ Inhibitory reflexes (GTO, other structures)

How might aging shift the relative distribution of type I and type II fibers?

↓ type II and ↑ type I