Chapter 13 & 21 SG: Test 4

what are the changes in fiber type distribution with aerobic endurance training for type I, IIa, and IIx?

increase in size and number of type 1 fibers (type 2 to type 1)

on a hot, humid day, what happens to the partial pressure of water?

increases

list and discuss the primary changes that occur in skeletal muscle as a result of endurance training

increases the volume of both mitochondrial population: subsarcolemmal and intermyofibrillar (mitochondrial biogenesis) -ATP is converted to ADP and Pi in the muscle fiber in order to develop tension. this increase in ADP concentration in the cytoplasm is the stimulus for mitochondrial oxidative phosphorylation -increased mitochondrial size

whole muscle hypertrophy as a result of resistance training is primarily due to what?

individual muscle fibers get larger

SAID principle

Specific Adaptations to Imposed Demands

second messengers: abbreviations and where each molecule is in the signaling pathway?

-AMPK: Glucose uptake, fatty acid oxidation, and mitochondrial biogenesis -PGC-1α (Master regulator for mitochondrial biogenesis. Endurance exercise): Increases in capillaries, mitochondria, antioxidant enzymes, Activated by p38 and CaMK -Calcineurin: Fiber growth, fast to slow fiber type change -NFkB: Antioxidant enzymes -PA/ Rheb/ mTOR (master regulator for resistance exercise): Muscle growth from resistance training.

at the cellular level, what changes are occurring in the muscle fiber following aerobic training?

-Capillary supply: increase number of capillaries supplying each fiber. May be key factor in increase in VO2max -Myoglobin: increase myoglobin content by 75 to 80%. Supports increase oxidative capacity in muscle. -Mitochondrial function: increase size and number. Magnitude of change depends on training volume -Oxidative enzymes (SDH, citrate synthase) : increase activity with training. Continue to increase even after VO2max plateaus. Enhanced glycogen sparing

what factors contribute to the loss of strength with age?

-Sarcopenia -Decline in strength after age 50 -Loss of both type 1 and type 2 fibers -Atrophy of type 2 fibers -Increase in intramuscular fat and connevtive tissue -Loss of motor units loss of muscle fibers -Reorganization of motor unit fibers

over drinking (hyper hydration) during exercise can cause:

-a loss of sodium from the blood and extracellular compartment (ECF) -a movement of fluid from the ECF into the ICF -a swelling and dysfunction of cells (including brain cells)

understand the contribution of heart rate, stroke volume, and the a-vO2 difference in determining VO2max

-cardiac output is determined by the product of heart rate times stroke volume. all training-induced increases in maximal CO must come from increases in stroke volume. exercise training does not increase maximal heart rate. -a-vO2 difference is a measure of how much oxygen is removed from arterial blood and used by the tissues.

state typical VO2 max values for various sedentary, active, and athletic populations

-cross-country skiers/distance runners: 72-84 -distance runners: 62-83 -sedentary young: 38-45 -sedentary middle-aged: 30-35 -diseased: 13-22

list and discuss the primary changes that occur in fiber type and capillarity as a result of endurance training

-fiber type: there is a shift in fast-to-slow muscle fiber type which involves a reduction in the amount of fast myosin in the muscle and an increase i slow myosin isoforms. this shift increases mechanical efficiency and improves endurance performance -capillarity: increases capillary supply to skeletal muscle fibers. is advantageous because diffusion distances for oxygen and substrate delivery to muscle fibers is reduced as well as the distance for diffusion and removal of metabolic waste from the fiber is decreased

list and discuss the three most common types of training programs used to improve VO2 max

-long, slow-distance exercise: performing exercise at a low intensity of 50-60% VO2 man or 60-70% max HR, for durations that are generally greater in length than thermal competition distance -high-intensity, continuous exercise: exercise intensity between 80-100% VO2 max are optimal. -altitude training: "live high, train low" training provides significant endurance performance gains

list the four primary signal transduction pathways in skeletal muscles

-mechanical stimuli: the mechanical force placed on the muscle fiber triggers signaling processes to promote adaptation -increases in cellular calcium: free calcium in the cytoplasm can activate numerous enzymes and other signaling molecules that promote proteins synthesis -elevated free radicals: are important signals for muscle adaptation to exercise training -decreases in muscle phosphate/energy levels: muscular exercise accelerates ATP consumption in the working muscle and increases the ratio of AMP/ATP in muscle fibers that can initiate numerous downstream signaling events in skeletal muscle fibers

explain how endurance training improves acid-base balance during exercise

-muscle buffering capacity is increased by high-intensity interval training. -endurance training results in less disruption of the blood pH during sub maximal work. -this is because endurance trained muscles produce less lactate and H+ -less lactate production is due to the increase in mitochondrial size and quantity -less H+ production is due to an increase in the number of shuttles used to transport electrons resulting in a quicker transportation to mitochondria and less H+ formed

contrast the role of neural adaptations with hypertrophy in the increase in strength that occurs with resistance training

-neural adaptations: the neural adaptations that occur in response to resistance training result in an improved ability to recruit motor units, alter motor neuron firing rates, enhance motor unit synchronization during a movement pattern, and result in the removal of neural inhibition which result in an increase in muscle force production -hypertrophy (increasing the size of existing fibers): primary means of increased muscle size from strength training; resistance training-induced increase in fiber cross-sectional area results from an increase in myofibrillar proteins (actin and myosin) who are due to the addition of sarcomeres in parallel to the existing sarcomeres. the addition of contractile proteins increases the number of myosin cross-bridges in the fiber and therefore increases the fiber's ability to generate force

explain why concurrent strength and endurance training can impair strength gains

-neural components: impairs motor unit recruitment which decreases muscle force production -glycogen depletion: beginning a training session with low muscle glycogen can reduce the ability to perform subsequent resistance training sessions and impair the magnitude of the strength-training adaptations -fiber-type transition: -overtraining: contributes to the inability to attain optimal strength gains when concurrent strength and endurance training is performed -impaired protein synthesis: endurance exercise training increases AMPK activation and promotes mitochondrial biogenesis. active AMPK can activate a signaling molecule called tuberous sclerosis complex 2 which inhibits mTOR activity and there fore impairs protein synthesis

explain the basic principles of training: overload, specialty, and reversibility

-overload: an organ system or tissue must be exercised at a level beyond which it is accustomed in order to achieve a training adaptation (intensity, duration, and frequency) -reversibility: fitness gains by exercising at an overload are quickly lost when training is topped and the overload is removed -specificity: effect that exercise training is specific to the muscles involved in that activity, the fibers recruited, the principle energy system involved (anaerobic vs aerobic), the velocity of contraction, and the type of muscle contraction (eccentric, concentric, isometric)

discuss how changes in "central command" and "peripheral feedback" following an endurance training program can lower the heart rate, ventilation, and catecholamine responses to a sub maximal exercise bout

-peripheral feedback: the cardiorespiratory control venter receives neural feedback from the working muscle resulting in output from the cardiorespiratory control center that increases both HR and Ve(pulmonary ventilation) -contral command: higher brain centers prepare to execute a motor task and send action potentials through lower brain centers and spinal nuclei to influence the cardiorespiratory and sympathetic nervous system responses to exercise. as more motor units are recruited to develop the greater tension needed to accomplish a work task, larger physiological responses are required to sustain he metabolic rate of the muscles resulting in a higher HR and increased pulmonary ventilation. the reduction in feed-forward output from higher brain centers results in lower sympathy nervous system output, HR, and Ve

what is the role of preload, afterload, and contractility on the increase in the maximal stroke volume that occurs with endurance training

-preload: an increase in EDV results in stretch of the left ventricle and a corresponding increase in cardiac contractility via the Frank-Starling mechanism. a primary mechanism for this is that plasma volume increases with endurance training and contributes to augmented venous return and increased EDV -afterload: trained muscles offer less resistance to blood flow during maximal exercise due to a reduction in the sympathetic vasoconstrictor activity to the arterioles of the trained muscles -contractility: increased force of ventricular contraction and increased left ventricular twist mechanics, also contractility refers to the strength of the cardiac muscle contraction when the preload, after load and heart rate remain constant, as they increase contractility increase

outline the signaling events that lead to endurance training-induced muscle adaptation

-repeated muscle contractions during sub maximal endurance exercise trigger a signaling cascade within the active muscle fibers leading to mitochondrial biogenesis, a shift in muscle fiber type from fast-to-slow, and increased expression of important antioxidant enzymes. -calcium release, increased AMP/ATP ratio, and production of free radicals are primary signaling events responsible for activation of the downstream, secondary signaling events that lead to mitochondrial biogenesis, fiber type transformation and increased expression of antioxidant enzymes -the primary signals to promote mitochondrial biogenesis occurs within the first few seconds after beginning exercise. wishing the first few minutes, the secondary signals involved increase within the muscle fibers. within a few hours following exercise, muscle levels of PGC-1æ rise and mitochondrial biogenesis proceeds. mitochondrial volume in the exercised muscles increases within days and continues as training proceeds.

what are the "big picture" changes that occur in skeletal muscle as a result of exercise training

-the exercise-inducted adaptation that occurs in muscle fibers is the result of an increase in the amount of specific proteins -specific types of proteins contained in a muscle fiber determine the muscle characteristics and its ability to perform specific types of exercise -muscle contraction during a training session generates a signal that promotes muscle adaptation by increasing primary and secondary messengers. these messengers initiate the cascade of coordinated signaling events, resulting in increased expression of specific genes and subsequently the synthesis of new proteins. in short, a bout of exercise generates a transient increase in the quantity of specific mRNAs which typically peaks during the first four to eight hours post-exercise and returns to basal levels within 24 hrs. exercise leads to a progressive increase in specific muscle proteins that improve muscle function

list and define the function of seven important secondary messengers in skeletal muscle

1. AMPK: regulates numerous energy producing pathways in muscle by stimulating glucose uptake and fatty acid oxidation during exercise. also linked to the control of muscle gene expression by activating transcription factors associated with fatty acid oxidation and mitochondrial biogenesis 2. P38: once activated, it can contribute to mitochondrial biogenesis by activated PGC-1æ. 3. PGC-1æ: considered the master regulator of mitochondrial biogenesis, assists in transcriptional activators that promote mitochondrial biogenesis. also regulated many other endurance exercise-mediated changes including formation of new capillaries (angiogenesis), a fast to slow muscle fiber type shift, and the synthesis of antioxidant enzymes. 4. CaMK: exerts influence on exercise-induced muscle adaptation by contributing to the activation of PGC-1æ 5. Calciuneurin Calciuneurin: removes a phosphate group from molecules, and participates in adaptive responses in muscle including fiber growth/regeneration and fast to slow fiber type transition 6. NFkB: a transcriptional activator that promotes the expression of several antioxidant enzymes that protect muscle fibers against free radical-mediated injuries 7. mTOR: a protein kinase that is a major regulator of protein synthesis and muscle size. promotes increased translation that results in increased protein synthesis in response to resistance training

second messengers: know the molecules involved in endurance training

AMPK, PGC-1æ, calcineurin, NFkB

what is the master regulator of protein synthesis in response to resistance exercise?

MTOR

describe overload

Must increase demands on body to make further improvements: -Muscle overload: muscles must be loaded beyond normal loading for improvement

Which molecule is the master regulator of mitochondrial biogenesis in response to endurance training?

PGC-1 alpha

describe variation or periodization

Systematically change one or more variables to keep training challenging: -Intensity, volume, and or mode -Increase volume/ decrease intensity -Decrease volume/ increase intensity

describe specificity

Training adaptations are specific: 1. Muscle fibers involved 2. Energy system involved 3. Velocity of contraction 4. Type of contraction

describe reversibility

Use it or lose it: -Training is improved strength and endurance -Detraining is the reverse (almost) all gains

what is Fick's equation for VO2max?

VO2 Max = maximal cardiac output x (maximal a-vO2 difference) as maximal oxygen uptake is the product of systemic blood flow (CO) and systemic oxygen extraction (a-v) training-induced changes in VO2 max occur due to increased maximal cardiac output, increased maximal a-vO2 difference, or some combination of both

relate the following to interval training: set

a specified number of work efforts per formed as a unit. number of sets depends on the purpose of training session and fitness level of athletes

discuss the role that genetics plays in determining VO2 max

about 50% of individual's VO2 max is determined by genetics along with environmental influences. the magnitude of improvement in VO2 max in response to exercise training is also genetically determined.

which part of the hypothalamus initiates sweating and increased blood flow to the surface in order to increase heat loss and cool the body during exercise?

anterior hypothalamus

describe the underlying causes of the decrease in VO2 max that occurs with cessation of endurance training

both maximal cardiac output and oxygen extraction decline over time with detraining. the initial decrease is due to the decrease in SV because the HR and a-vO2 difference remained the same or increased. the sudden decrease in maximal stroke volume appears to be due tot he rapid loss of plasma volume. the prolonged decrease is due to a decrease in a-vO2 difference which is associated with a decrease in muscle mitochondria where capillary density remained unchanged.

the strength gains in the first two months of training are mainly due to what?

change in neural factors (e.g. motor unit recruitment)

compare the time course of detraining between resistance and aerobic endurance training

detraining of resistance training is slower than endurance training.

describe individuality

each person has unique abilities and needs

which method is most effective for heat loss during exercise?

evaporation

which method of heat loss during exercise requires a vapor pressure gradient in order to effectively function?

evaporation

how can interval training be used to improve both aerobic and anaerobic power?

exercises that exceed VO2 max is possible because the ATP used to preform at these high work rates comes from the combination of both aerobic and anaerobic sources.

T or F: past the age of about 50, it is very difficult to gain muscle mass and improve strength and power.

false

what are the changes in fiber type distribution with resistance training for type I, IIa and IIx?

hyper trophy or enlargement of both type 1 and type 2 fibers. type 2x to type 2a transition is common

sarcopenia

loss of muscle mass

second messengers: know the molecules involved in resistance training

mTOR

second messengers: which 2nd messenger is the "master regulator" of mitochondrial biogenesis

mTOR

what molecule in the intercellular signaling pathway in inhibited by TSC in response to aerobic exercise?

mTOR

outline the signaling events that lead to resistance training-induced increases in muscle growth

mTOR is the primary activator of muscle protein synthesis. resistance exercise triggers muscle signaling events that activate mTOR leading to increased protein synthesis. this process begins with contraction-induced activation of a mechanoreceptor on the fiber membrane that can activate mTOR in two ways. first, exercise-mediated mechanoreceptor signaling activates another mTOR activator, Rheb. this occurs because muscle contractions activate the enzyme, Erk, which phosphorylates the Rheb inhibition of Rheb which enable Rheb to active mTOR. these exercise--mediated signaling actions activate and promote muscle protein synthesis.

how does retraining influence muscle fiber size and strength?

only six weeks of retraining resulted in rapid regaining of dynamic muscular strength and a complete restoration of muscle fiber size back tot he peak training levels. rapid muscular adaptations occur as a result of the reinstatement of strength training in previously trained people.

identify the primary changes that occur in skeletal muscle fibers in response to resistance training

resistance training has also been shown to promote a fast-to-slow shift in muscle fiber types of type IIx to type IIa (no increase of type I) within the trained muscles but are less prominent than endurance training.

at the cellular level, what changes are occurring in the muscle fiber following resistance training?

resistance training leads to synchronous recruitment: -Facilitates contraction -May produce more forceful contraction -Improves rate of force development -Increase capability to exert steady forces

compare the time course of retraining for resistance and aerobic endurance training

retraining is quicker in people who have previously trained. regained within one week. resistance training takes longer to regain, maybe up to three weeks.

explain how knowledge of the energy systems used in a particular activity or sport might be useful in designing a sport-specific training program

sport specific improved performance can be achieved by increasing the muscle's ability to generate force and power improving muscular efficiency and increasing muscle endurance. different sports use different metabolic pathways or energy systems to produce the ATP needed for that movement. an understanding of exercise metabolism in important because the design of a program to optimize athletic performance requires knowledge of the principal energy systems utilized by the sport.

discuss how training increases VO2 max

the Fick equation reveals that training0induced increases in VO2max can be due to increased cardiac output, increased a-vO2 difference or an increase in both. all of the training induced improvements in VO2 max is due to increases in maximal cardiac output. it takes a lot longer to increase a-vO2 difference. the exercise induced increase in maximal cardiac output is entirely due to increases in stroke volume because maximal heart rate doesn't change.

and discuss the specificity of exercise-training responses to exercise

the features of exercise-induced muscle adaptation are specific to the training volume, intensity, and frequency. the specific adaptations that occur in skeletal muscle fibers result from the type of exercise stimulus. different exercise types promote the expression of different genes in the active muscle fibers and different cell signaling pathways and different genes are activated resulting in diverse expression of proteins

list the general principles of strength development

the goal of a strength-training program is to increase the maximum amount of force and power that can be generated by a particular muscle groups. improvement in muscular strength can be achieved via progressive overload by using either isometric, isotonic, or isokinetic exercise

relate the following to interval training: work interval

the length and intensity of the work interval depends on what the athlete is trying to accomplish. the long of the work interval refers to the distance to be covered during the work effort

relate the following to interval training: work-to-rest ratio

the length of rest interval is generally expressed as a ratio of the duration of the work interval. rest should at least be as long as the work. or a 1:1 ratio. for those who are not already training a work to rest ratio of 1:3 or 1:2 may be preferred

discuss how detraining following strength training affects muscle fiber size and strength

the rate of detraining after a resistance training program is slower than endurance training. much of the loss of strength associated with detraining is associated with changes in the nervous system. following 30 weeks of detraining, a 31% decrease in maximal dynamic muscle strength was shown.

relate the following to interval training: rest interval

the time between work efforts and consists of light activity such as walking.

describe the changes in muscle structure that are responsible for the increase in the maximal a-vO2 difference with endurance training

the training-induced increase in the a-vO2 different is due to increased O2 extraction from the blood. this is caused by an increase in capillary density, and mitochondrial volume. the bigger density allows for increased muscle blood flow, decreased diffusion distance to mitochondria, and lower rate of blood flow to allow more time for oxygen diffusion from the capillary to the muscle fiber. the increase in mitochondrial number increases the muscle fiber's ability to consume oxygen to expand a-vO2 difference.

indicate the typical change in VO2 max with endurance-training programs and the effect of the initial (pretraining) value on the magnitude of the increase

typically increased VO2 max of 15-20% but can be as low as 2-3% if they have a high VO2max

which principle is violated when an individual does the same workout overtime he/she goes to workout, week after week, year after year?

variation