Guyton and Hall Physiology Chapter 85 - Sports Physiology
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Questions and Answers

Which fiber type is primarily responsible for endurance activities and prolonged muscle contraction?

  • Super-fast fibers
  • Slow-twitch fibers (correct)
  • Intermediate fibers
  • Fast-twitch fibers

    • What is the main change in muscle composition observed after extensive training in athletes?

  • Decrease in mitochondrial enzymes
  • Increase in the components of the phosphagen metabolic system (correct)
  • Increase in fast-twitch fibers only
  • Decrease in stored triglycerides

    • How does training frequency affect maximal oxidation rate?

  • It has no impact on oxidation rate
  • It decreases oxidation efficiency
  • It only affects anaerobic systems
  • It can increase the maximum oxidation rate and efficiency (correct)

    • Which athlete is likely to have a higher percentage of fast-twitch muscle fibers?

    <p>Sprinter</p> Signup and view all the answers

    What role does respiration play in performance for endurance athletes?

    <p>It is only critical for endurance athletics</p> Signup and view all the answers

    What primarily influences the energy source used during the early stages of exercise?

    <p>A high-carbohydrate diet</p> Signup and view all the answers

    Which of the following statements about aerobic and anaerobic systems is true?

    <p>Aerobic systems require oxygen to generate energy</p> Signup and view all the answers

    Which type of muscle fibers typically contain more mitochondria?

    <p>Slow-twitch fibers</p> Signup and view all the answers

    What percentage of glycogen storage increase has been observed with proper training?

    <p>50% to 60%</p> Signup and view all the answers

    Fast-twitch muscle fibers are best characterized by which of the following?

    <p>They generate quick, explosive movements</p> Signup and view all the answers

    What is attributed to muscle hypertrophy?

    <p>Strength training combined with adequate dietary intake</p> Signup and view all the answers

    During intense exercise, how does the energy source shift as fatigue approaches?

    <p>From carbohydrates to fats</p> Signup and view all the answers

    What happens to muscle mass in individuals who become excessively sedentary in old age?

    <p>Muscle mass atrophies drastically</p> Signup and view all the answers

    Which type of muscle fibers are generally associated with superior performance in short, high-intensity activities?

    <p>Fast-twitch fibers</p> Signup and view all the answers

    Hypertrophy of muscle fibers primarily results from an increase in which of the following?

    <p>Diameter of muscle fibers</p> Signup and view all the answers

    What role does testosterone play in muscle development?

    <p>Promotes larger muscle size in men</p> Signup and view all the answers

    Which factor is least likely to contribute to a person's athletic capabilities?

    <p>Body fat percentage</p> Signup and view all the answers

    What percentage increase in muscle fiber hypertrophy can result from training?

    <p>30% to 60%</p> Signup and view all the answers

    Which type of training primarily enhances the number of myofibrils in muscle fibers?

    <p>Resistance training</p> Signup and view all the answers

    Which athletic discipline is more likely suited for individuals with a predominance of slow-twitch muscle fibers?

    <p>Marathon running</p> Signup and view all the answers

    What is a primary characteristic of anaerobic energy systems during exercise?

    <p>Quick bursts of energy with rapid fatigue</p> Signup and view all the answers

    What physiological change occurs in muscle fibers due to intensive training?

    <p>Increase in the number of myofibrils</p> Signup and view all the answers

    Which of the following factors does NOT significantly influence the relative proportions of fast-twitch and slow-twitch fibers?

    <p>Dietary habits</p> Signup and view all the answers

    What is the significance of a high-carbohydrate diet for athletes in terms of endurance?

    <p>It allows for longer sustained exercise.</p> Signup and view all the answers

    How does the holding strength of muscles compare to contractile strength?

    <p>Holding strength is about 40% greater.</p> Signup and view all the answers

    Which type of diet yields the lowest amount of glycogen stored in the muscle before a race?

    <p>High-fat diet</p> Signup and view all the answers

    What occurs when a muscle is forcibly stretched while maximally contracted?

    <p>It can lead to internal tearing.</p> Signup and view all the answers

    What differentiates power from strength in muscle contraction?

    <p>Power accounts for work done over time.</p> Signup and view all the answers

    During which type of exercise is muscle soreness most likely to occur?

    <p>Forceful stretching of a contracted muscle.</p> Signup and view all the answers

    What happens to the force output of the muscle during a holding contraction compared to a shortening contraction?

    <p>It requires more force due to higher resistance.</p> Signup and view all the answers

    How long can a marathon runner typically sustain their race with a mixed diet?

    <p>120 minutes.</p> Signup and view all the answers

    Which muscle fiber type is more likely to contribute to endurance activities?

    <p>Slow-twitch fibers</p> Signup and view all the answers

    Which of the following describes the primary energy system utilized during high-intensity sprinting?

    <p>Anaerobic system</p> Signup and view all the answers

    What role does myoglobin play in muscle fibers?

    <p>It combines with oxygen and shuttles it within the muscle fiber.</p> Signup and view all the answers

    Which type of muscle fibers primarily support endurance activities?

    <p>Slow-twitch fibers</p> Signup and view all the answers

    How does the number of capillaries differ between slow-twitch and fast-twitch fibers?

    <p>Slow-twitch fibers have a greater number of capillaries.</p> Signup and view all the answers

    What is a key characteristic of fast-twitch muscle fibers?

    <p>They generate quick bursts of power.</p> Signup and view all the answers

    Which metabolic system's enzymes are more active in slow-twitch fibers?

    <p>Aerobic metabolic system</p> Signup and view all the answers

    What is the primary benefit of resistive training over a 10-week period?

    <p>Significant increase in muscle strength</p> Signup and view all the answers

    What distinguishes aerobic energy systems from anaerobic energy systems?

    <p>Anaerobic systems do not require oxygen.</p> Signup and view all the answers

    What is the effect of training frequency on muscle hypertrophy?

    <p>Optimal frequency is key for maximizing muscle growth.</p> Signup and view all the answers

    Which type of muscle fibers are primarily suited for short bursts of high-intensity activities?

    <p>Fast-twitch fibers</p> Signup and view all the answers

    What is the impact of myoglobin levels on muscle performance?

    <p>Increased myoglobin improves oxygen transport to muscle fibers.</p> Signup and view all the answers

    Which energy system is predominantly used in a 100-meter dash?

    <p>Phosphagen system</p> Signup and view all the answers

    How much oxygen debt is typically associated with a 400-meter dash?

    <p>8 liters</p> Signup and view all the answers

    During which exercise do you mainly utilize the glycogen–lactic acid system?

    <p>Baseball triple</p> Signup and view all the answers

    What contributes primarily to the reconstitution of the lactic acid system post-exercise?

    <p>Removal of excess lactic acid</p> Signup and view all the answers

    Which sports event is most likely to have no significant rate of oxygen uptake during performance?

    <p>Ice hockey dashes</p> Signup and view all the answers

    What is a potential risk of using certain drugs during athletic events?

    <p>Increase in heart overexcitability</p> Signup and view all the answers

    What factor is associated with prolonged life in individuals aged 50 to 70 years?

    <p>Maintaining appropriate body fitness</p> Signup and view all the answers

    What physiological response is likely to occur due to exercise and weight management?

    <p>Improved cardiovascular fitness</p> Signup and view all the answers

    What can be a consequence of the interaction between performance-enhancing drugs and neurotransmitters during exercise?

    <p>Death due to lethal arrhythmias</p> Signup and view all the answers

    According to recent studies, how can the concepts of VO2max and trainability be characterized?

    <p>Context dependent and affected by multiple variables</p> Signup and view all the answers

    What is the primary factor that contributes to the increased strength observed in resistive training over a 10-week period?

    <p>Increased muscle mass and hypertrophy</p> Signup and view all the answers

    Which advantage do slow-twitch fibers have over fast-twitch fibers?

    <p>Greater endurance for prolonged activities</p> Signup and view all the answers

    How does the presence of myoglobin impact muscle function?

    <p>It enhances the transport of oxygen within muscle fibers</p> Signup and view all the answers

    What physiological change occurs due to resistance training in terms of capillary density?

    <p>Increased capillary density around slow-twitch fibers</p> Signup and view all the answers

    What role do enzymes in slow-twitch fibers play compared to fast-twitch fibers?

    <p>They are more active, supporting aerobic metabolism</p> Signup and view all the answers

    What is a characteristic of fast-twitch fibers regarding their energy system adaptation?

    <p>Greater anaerobic energy production</p> Signup and view all the answers

    What does increased muscle hypertrophy primarily result from in trained individuals?

    <p>An increase in muscle fiber size</p> Signup and view all the answers

    Which statement best describes the power output capabilities of fast-twitch fibers?

    <p>They deliver extreme amounts of power for short periods</p> Signup and view all the answers

    What is a noted difference between the training responses of fast-twitch versus slow-twitch muscle fibers?

    <p>Fast-twitch fibers show little improvement with endurance training</p> Signup and view all the answers

    The holding strength of muscles is about 40% less than the contractile strength.

    <p>False</p> Signup and view all the answers

    A high-carbohydrate diet allows a marathon runner to sustain the race for approximately 240 minutes.

    <p>True</p> Signup and view all the answers

    The power of muscle contraction is a measure of the total amount of work performed in a specific period of time.

    <p>True</p> Signup and view all the answers

    The force experienced during holding contractions is less than during shortening contractions.

    <p>False</p> Signup and view all the answers

    The amounts of glycogen stored in muscle for a high-fat diet is approximately 20 g/kg muscle.

    <p>False</p> Signup and view all the answers

    Phosphocreatine provides energy to convert AMP and ADP into ATP.

    <p>True</p> Signup and view all the answers

    The phosphagen energy system provides maximal muscle power for 12 to 15 seconds.

    <p>False</p> Signup and view all the answers

    Muscle cells typically contain more ATP than phosphocreatine.

    <p>False</p> Signup and view all the answers

    The phosphagen system generates ATP at a lower rate than the glycogen-lactic acid system.

    <p>False</p> Signup and view all the answers

    Energy transfer from phosphocreatine to ATP occurs rapidly, within a fraction of a second.

    <p>True</p> Signup and view all the answers

    Muscle contractions during endurance events primarily rely on glycogen reserves for energy after 5 hours.

    <p>False</p> Signup and view all the answers

    Optimal muscle strength increases occur with three sets of maximal contractions performed four times a week.

    <p>False</p> Signup and view all the answers

    Endurance athletic events lasting longer than 4 hours are ideal for depleting fat stores.

    <p>False</p> Signup and view all the answers

    Muscles receive energy primarily from proteins during prolonged contractions.

    <p>False</p> Signup and view all the answers

    Muscle strength plateaus approximately after the first 6 to 8 weeks of resistive training.

    <p>True</p> Signup and view all the answers

    A decrease in muscle strength can occur due to chronic muscle fatigue from excessive training.

    <p>True</p> Signup and view all the answers

    A significant amount of glycogen is still available for muscle contraction after 4 hours of endurance exercise.

    <p>False</p> Signup and view all the answers

    In resistive training, energy utilization shifts from fats to carbohydrates after 30 minutes.

    <p>False</p> Signup and view all the answers

    Acetoacetic acid is a significant energy source for muscles during high-intensity contractions.

    <p>False</p> Signup and view all the answers

    Muscle strength increases are less efficient when not performing maximal contractions.

    <p>True</p> Signup and view all the answers

    Match the following substances with their primary effects:

    <p>Androgens = Increase muscle strength and athletic performance Amphetamines = Reputed to boost athletic performance Cocaine = Overuse can lead to performance deterioration Anabolic steroids = Increase risk of cardiovascular disease</p> Signup and view all the answers

    Match the following effects with the correct population:

    <p>Decreased testicular function = Men using male sex hormones Facial hair growth = Women using male sex hormones Cessation of menses = Women taking androgens Increased risk of hypertension = Both genders using anabolic steroids</p> Signup and view all the answers

    Match the following health benefits to their related activities:

    <p>Regular exercise = Improved insulin sensitivity Increased fitness = Reduction in cancer risk Weight loss = Independent of chronic disease risk reduction Muscle training = Enhances athletic performance</p> Signup and view all the answers

    Match the following hormones with their primary roles:

    <p>Testosterone = Supports male sexual characteristics Androgens = Promote muscle growth Insulin = Regulates blood sugar levels Estrogen = Regulates female reproductive functions</p> Signup and view all the answers

    Match the following risks with their associated substances:

    <p>Anabolic steroids = Cardiovascular disease risk Cocaine = Deterioration of performance Amphetamines = Potential increase in athletic performance Excessive testosterone = Long-term male hormone side effects</p> Signup and view all the answers

    Match the following hormones with their effects on the body:

    <p>Testosterone = Increases protein deposition in muscles Estrogen = Increases fat deposition, especially in breasts and hips Cortisol = May contribute to muscle breakdown Insulin = Facilitates glucose uptake by cells</p> Signup and view all the answers

    Match the following age groups with their average body fat composition:

    <p>Young female (16-19 years) = 34% body fat Young male (16-19 years) = 23% body fat Adult female = Varies based on activity level Adult male = Typically lower than females</p> Signup and view all the answers

    Match the following exercise stress levels with their potential impacts:

    <p>Extreme exercise = May lead to lethal body metabolism Moderate exercise = Enhances cardiovascular health Lethal fever = Increases metabolism to 100% above normal Marathon race = Increases metabolism to 2000% above normal</p> Signup and view all the answers

    Match the following effects with the corresponding genders in sports physiology:

    <p>Male athletes = Typically have larger muscles due to testosterone Female athletes = Higher body fat percentage due to estrogen Sedentary males = Potential for lower muscle mass Sedentary females = May retain higher fat deposits</p> Signup and view all the answers

    Match the following physiological mechanisms with their descriptions:

    <p>Protein deposition = Stimulated by testosterone Fat deposition = Stimulated by estrogen Body metabolism during extreme exercise = Can double or exceed normal levels Muscle hypertrophy = Result of consistent resistance training</p> Signup and view all the answers

    Study Notes

    Muscle Fiber Types

    • Fast-twitch muscle fibers are used for forceful and rapid contractions, examples include the gastrocnemius muscle
    • Slow-twitch muscle fibers are used for prolonged muscle activity. Example is the soleus muscle
    • Muscle size is determined by heredity and testosterone.
    • Muscle hypertrophy - increase in muscle fiber diameter.
    • Increase in muscle fiber diameter results in increased numbers of myofibrils
    • Muscle hypertrophy can increase muscle strength and mass
    • Muscle strength can increase 30%-60% with training
    • Some muscle fibers split in half to create new fibers

    Energy Systems

    • Anaerobic and aerobic systems increase in capacity with training
    • Aerobic system increases maximum oxidation rate by 45%

    Respiration in Exercise

    • Respiration plays a large role in endurance athletics, it is less important in sprinting
    • Fast-twitch muscle fiber percentage is higher in sprinters and lower in marathoners
    • The average male has 55% fast-twitch fibers and 45% slow-twitch fibers
    • Genetics can influence muscle fiber type, some people are born with more fast-twitch fibers and others have more slow-twitch fibers
    • Genetics can influence athletic talent, some people are born to be marathoners, others are born to be sprinters
    • Slow-twitch fibers are more efficient at using oxygen, they have more mitochondria and myoglobin.

    Muscle Strength, Endurance, and Power

    • Muscle holding strength is 40% greater than contractile strength
    • Power is a measure of work performed in a unit of time
    • People can run longer on a high-carbohydrate diet than on a high-fat diet
    • Muscle strength can improve by more than 100% in old age if people become active again

    Capillary Differences

    • Slow-twitch fibers have more capillaries surrounding them than fast-twitch fibers
    • Fast-twitch fibers provide power for short bursts of activity
    • Slow-twitch fibers provide endurance for longer activities

    Heart Failure

    • Stimulants have not been proven to be effective in treating patients with heart failure
    • Stimulants can be harmful to athletes as they can interact with adrenaline, increasing the risk of heart failure

    Exercise and Longevity

    • Maintaining good fitness can increase lifespan.
    • People aged 50-70 are especially likely to benefit from this.

    The "Oxygen Debt"

    • An increase in oxygen intake post-exercise is known as the "oxygen debt"
    • This is because lactic acid created during exercise needs to be removed from the body fluids
    • The oxygen debt can last for extended periods as the body recovers

    Muscle Fiber Types

    • Slow-twitch muscle fibers are more efficient at endurance activities
    • Slow-twitch fibers contain more myoglobin, which assists in oxygen delivery
    • Slow-twitch fibers contain higher levels of enzymes for aerobic metabolism
    • Slow-twitch fibers have a greater number of capillaries surrounding them
    • Fast-twitch fibers are designed for short, powerful bursts of energy

    Resistive Training

    • Resistive training can lead to a significant increase in strength, up to 30% over 10 weeks
    • Resistive training works by increasing muscle pressure and blood flow.

    Cardiovascular System in Exercise

    • During exercise, the blood flow to muscles increases significantly
    • This is driven by increased cardiac output & vasodilation - the widening of blood vessels
    • Trained athletes are able to achieve higher cardiac outputs, up to 7-8 times their resting levels
    • Trained athletes have larger heart chambers and 40% more heart mass contributing to the increased output.

    Relation Between Work Output, Oxygen Consumption, and Cardiac Output

    • Increased Work Output translates to increased Oxygen Consumption and Cardiac Output
    • Cardiac output increases by both increased stroke volume (amount of blood pumped per beat) and increased heart rate.
    • Stroke volume plateaus early in exercise, meaning increased heart rate is responsible for further increases in cardiac output.

    Muscle Strength and Holding Strength

    • Holding strength is about 40% greater than muscle strength.
    • Holding strength is the force required to stretch a contracted muscle.
    • This is relevant for landing from jumps and can cause damage to tendons, joints, and ligaments.

    Energy Systems in Muscle

    • Muscle relies on the phosphagen system for short-term energy needs (8-10 seconds).
    • The phosphagen system includes ATP and phosphocreatine.
    • The phosphagen system provides maximum muscle power for short bursts.
    • The glycogen-lactic acid system provides energy for a longer time but at a lower rate than the phosphagen system.
    • The aerobic system provides energy for the longest period but at the lowest rate.

    Energy Sources During Endurance Exercise

    • The body primarily uses carbohydrates for energy during the initial stages of endurance exercise.
    • As exercise continues, the body relies more on fat for energy, utilizing a mix of fatty acids and acetoacetic acid.
    • Glycogen depletion occurs after ~ 4 to 5 hours, and muscles rely almost entirely on fats for energy after this point.

    Muscle Hypertrophy

    • Muscle hypertrophy refers to muscle growth, which can be influenced by heredity and testosterone levels.
    • Training can increase muscle size by 30% to 60%.
    • Muscle growth predominantly results from increased fiber diameter, not the formation of new fibers.
    • While rare, some muscle fibers can split longitudinally to create new fibers.

    Fast-twitch and Slow-twitch Muscle Fibers

    • Fast-twitch muscle fibers are larger than slow-twitch fibers.
    • Fast-twitch fibers have higher enzyme activity for energy release compared to slow-twitch fibers.
    • Fast-twitch fibers are better for short bursts of power.
    • Slow-twitch fibers are optimized for endurance, better for sustained aerobic activity.
    • Genetic factors influence the proportion of fast-twitch and slow-twitch fibers, impacting athletic potential for different sports.

    Oxygen Consumption and Exercise

    • Normal oxygen consumption at rest is about 250 ml/min.
    • During maximal exercise, oxygen consumption can increase to 3600 ml/min for an untrained male.
    • Trained athletes can reach higher levels, with marathon runners reaching 5100 ml/min.
    • The increase in oxygen consumption and ventilation during exercise indicates how training improves the body's capacity for aerobic activity.

    Training and V̇o2 Max

    • V̇o2 Max is the maximum volume of oxygen a person can use during exercise.
    • V̇o2 Max increases with training.
    • The increase in V̇o2 Max is greater with more frequent and intense training.
    • V̇o2 Max plateaus after a certain level of training.

    Hereditary Differences in Muscle Fiber Type

    • Genetics plays a significant role in the proportion of fast-twitch and slow-twitch muscle fibers.
    • Individuals with higher proportions of fast-twitch fibers are better suited for sprinting and jumping.
    • Individuals with higher proportions of slow-twitch fibers are better suited for endurance activities like marathon running.

    Sports Physiology - Male & Female Athletes

    • Male sex hormones (androgens), including anabolic steroids, increase muscle strength and athletic performance in men and women.
    • Anabolic steroids can lead to cardiovascular issues like hypertension, lowered high-density lipoproteins, and increased low-density lipoproteins, increasing the risk of heart attacks and strokes
    • Male sex hormone preparations decrease testicular function, reducing sperm production and natural testosterone levels in men.
    • The effects of male sex hormone use in women include: facial hair, deeper voice, ruddy skin, and cessation of menstruation, due to their bodies not being adapted to male hormones.
    • Testosterone significantly impacts muscle growth, contributing to the 40% larger muscle mass in men compared to women.
    • Estrogen plays a role in body composition differences between genders, contributing to the higher body fat percentage in women.
    • Young nonathletic females typically have a 34% body fat composition, while young nonathletic males have a 23% body fat composition.

    Oxygen Consumption & Pulmonary Ventilation

    • Pulmonary ventilation increases 20-fold between rest and maximum exercise in well-trained athletes.
    • Exercise increases pulmonary ventilation by: direct stimulation of the respiratory center and sensory signals from contracting muscles.
    • Smoking decreases athletic "wind" by: constricting bronchioles, increasing airflow resistance in the lungs
    • Trained athletes’ resting heart rate is lower despite their higher oxygen consumption compared to untrained individuals.

    Impact of Exercise on Heart, Blood Flow, & Temperature

    • The marathoner's exceptional cardiovascular system is crucial for their performance, as it is the limiting factor for delivering oxygen to muscles.
    • The marathoner's ability to increase their cardiac output by 40% compared to untrained individuals is a significant benefit of training.
    • Heart disease significantly affects performance, as it reduces the heart's ability to pump blood efficiently, resulting in lower muscle power.
    • Exercise increases blood flow in muscles, but the contractile process itself temporarily decreases blood flow due to muscle compression of blood vessels.
    • High-intensity exercise can lead to an increase in core body temperature, posing a risk of heat stroke.
    • Heatstroke causes excessive heat production and can result in death if not treated immediately.
    • Treatment for heatstroke involves rapidly reducing body temperature by removing clothing and applying cooling measures.

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    Description

    This quiz covers the different types of muscle fibers, including fast-twitch and slow-twitch, and their roles in muscle strength and hypertrophy. Additionally, it discusses energy systems and the respiration process during exercise, focusing on endurance vs. sprinting athletes. Test your knowledge on how these concepts interrelate in physical performance!

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