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CH 5 Physiology of Training
From ACE exam
Terms in this set (73)
Represents the increased respiratory response to remove extra CO2 produced by the buffering of lactate as it begins to accumulate in the blood.
Represents the blood buffering systems becoming overwhelmed by rapidly increasing blood lactate
Hormones that ensure blood glucose maintenance during exercise and quickly return blood glucose concentrations back to normal after exercise
Catecholamines (Epinephrine and Norepinephrine)
-Increase cardiac contractility, leading to increased cardiac output
-Vasoconstriction of non-working muscles increases total peripheral resistance, causing an increase in systolic blood pressure (SBP)
-Dialates respiratory passages and reduces digestive activity and bladder emptying
-Stimulates the mobilization of stored carbohydrates and fats, the productions and release of glycogen, and the glycegonolysis in skeletal muscle.
-Activation of the sympathetic system during exercise suppresses the release of insulin from pancreas.
-Insulin sensitivity increases, requiring less insulin for the same effect.
-Glucose uptake by the skeletal muscle occurs at higher rate.
-Glucagon, also released from the pancreas, stimulates an almost immediate release of glucose from the liver.
-Facilitates an increase in blood glucose levels in response to low levels (negative feedback loop)
-This reaction takes effect as exercise progresses and glycogen stores deplete
Slow Acting Hormone.
-Released by the adrenal cortex, stimulates the mobilization of free fatty acids (FFA) from adipose tissue, mobilizes glucose synthesis in the liver, and decreases the rate of glucose utilization in the cells.
-Increases with intensity and stress on the body.
-Prolonged elevated levels have been linked to excessive protein breakdown, tissue wasting, negative nitrogen balance and abdominal obesity.
Slow Acting Hormone
-Released by the anterior pituitary gland, supports the action of cortisol and plays a role in proteing synthesis
-Dramatic increase during short-term physical activity
Carbohydrates (Fuel use during exercise)
-Carbohydrates are the major food macronutrient for the metabolic production of adenosine triphosphate (ATP) and the only one who stored energy can produce ATP anaerobically
Carbohydrates (Fuel Use During Exercise II)
-Carbohydrates used during exercise comes from both glycogen stores in muscle tissue and blood glucose.
-The relative contribution of muscle glycogen and blood glucose used during exercise is determined by intensity and duration.
-After the 1st hour of submaximal exercise, carbohydrate metabolism shifts from muscle glycogen to glycogenolysis in the liver
Fats used as Fuel during Exercises
-Fats mainly stored as tryglycerides in adipocytes, which must be broken down into FFA's and glycerol
-During low-intensity exercise, circulating FFA's from adipocytes are primary energy source from fat, but during higher intensities, muslce triglyceride metabolism increases
-As duration increases, the role of plasma FFA's as a fuel source increases.
-Protein plays a small role in the fueling of exercise. It must be broken down into amino acids, which can be supplied to the muscle tissue from the blood and from the muscle fiber itself.
-Skeletal muscle can directly metabolize certain amino acids to produce ATP.
-During exercise, glucose stored in a non-exercising muscle can be delivered indirectly to the exercising muscle via the glucose-alanine pathway.
Energy system during exercise
-Rate of ATP production: Very rapid substrate: creatine phosphate, ATP
-System Capacity: Very limited
-Utilization: High-intensity, very short-duration activities
-Limitations: Limited Energy supply
Rate of ATP production: Rapid
-Substrate: Blood/muscle glucose,
-Glycogen system capacity: Limited
-Utilization: High-Intensity, short duration activities
-Limitations: Lactic Acid Production
Rate of ATP production: Slow
-Substrate: Blood Glucose
-System capacity: unlimited
-Utilization: Lower intensity, longer
-Limitations: Slow rate of oxygen
-Lactate is generally thought of as a waste product of glycolysis
-Plays a role in glucose production in the liver (Glucon Eogenesis)
-During exercise, some of the lactic acid produced by skeletal muscle is transported to the liver via the blood and converted back to glucose and released into the blood system, traveling back to the skeletal muscles to be used as an energy source.
-The cycle of lactate to glucose between the muscle and the liver is called the coricycle
-Serves as a direct fuel source for skeletal muscle and the heart.
-Muscle contractility depends on maximal force production, speed of contraction, and muscle fiber efficiency
-Fast twitch muscle fibers contain more myosin cross-bridges per cross-sectional area of fiber and produce 10%-20% more force than slow-twitch muscle fibers
-Fast Twitch muscle fibers are more efficient at using oxygen to generate ATP to fuel continuos muscle contractions due to their higher concentrations of myoglobin, larger number of capillaries, and higher mitochondrial enzyme activity.
-Muscle fatigue is associated with an acute bout of prolonged exercise in which muscular performance declines and sensations of muscle pain occur.
-When muscle glycogen is depleted, an increase in the use of fat for energy occur
-When muscle glycogen is depleted, an increase in the use of fat for energy occurs
-Fat mobilization and oxidation are much slower, resulting in a reduction of power output of the muscle.
-Drinking a glucose and water solution near the point of fatigue may help for a short time, but glycogen will remain depleted.
-High carbohydrate diets (>60% of calories from carbohydrats) and carbohydrate loading can extend performance before "hitting the wall"
Mechanisms of Thermoregulation
In the heat:Thermal core receptors signal the hypothalamus that core temperature is rising, which directs the nervous system to commence sweating and increase blood flow to the skin,
-While 4 mechanisms are used to give off heat, evaporation is the major contributor to exercise
-Adaptations can take place as early as 9-14 days.
-Increased plasma volume
-Decreased heart rate and core temperature
-Increased sweat rate
Exercise in the Cold
Three primary ways in which the body avoids excessive heat loss
-Air and water are the two major cold stressors
-As wind chill increases, so does the risk of freezing body tissues
-The body loses heat 4-5x's faster in water than in air of the same temperature
Chronic Adaptations to Exercise
-Regular, consistent exercises lead to several adaptations that allow the body to improve performance
-Cardiorespiratory endurance capacity is determined by the ability of the cardiovascular and respiratory systems to deliver oxygen to activate tissues, and the ability of those tissues to extract and use the oxygen during the prolonged bouts of exercise
Cardiac output factors: Decreased HR at any submax: mal effort, including rest.
Oxygen Exercise Factors: Increased Capillary density
Cardiorespiratory Change to Exercise
Change in Blood Volume
-Increase in Blood Volume
-An initial, rapid adaptation to exercise
-Increase is due primarily to plasma and, to a lesser extent, red blood cells
-Plasma volume can incraese 12%-20% after 3-6 aerobic-training workouts
-The number of red blood cells may increase, but the ratio of red blood cell volume to total blood volume may decrease
Cardiorespiratory Changes to Exercise (Heart size and Volume)
-Increase as an adaptation to increased work demand, but return to pre-training levels within several weeks if training ceases.
-Characterized by an increase of the left ventricular cavity and slight thickening of the walls.
-Increase in size due to endurance training and an increase in blood volume.
-These adaptations lead to an increase in cardiac force and the amount of blood pumped per beat
-Decreased resting heart rate (RHR) and exercise heartrate for longer diastolic and reduced work 4 heart. Filling
-Improved maximal oxygen uptake (VO2 max) and decreased cardiac stress.
Used to determine the rate at which oxygen is being used during physical activity.
-VO2= Qxa-VO2 difference
Q= Cardiac Output (HR x SV)= oxygen delivery
a-VO2 difference= oxygen extraction
Stroke Volumes (SV) for different states of training
Fick Equation Components
Improvements in VO2max are due to increases in one or more of the following variables:
-Stroke Volume: Increases at rest and during exercise result from regular training
-Regular training typically yields:
-Decreased RHR of more than 10 bpm
-Decreased submaximal heart rate of 10-20 bpm
-A VO2 difference: Increases with training, and is reflective of greater oxygen extraction at the tissue level and more effective distribution of blood flow to active tissues.
Cardiorespiratory Changes Blood Flow
Increased bloodflow to working muscles is enhanced through regular endurance training due to: Increased capillarization of trained muscles, greater recruitment of existing capillaries in trained muscles, more effective blood flow redistribution from inactive areas to activate tissues, increased blood volume.
Cardiorespiratory Changes Pressure
-In response to regular endurance training, a decrease in resting SBP and DBP is noted only for borderline or moderately hypertensive individuals
-Resistance training may also reduce SBP
Cardiorespiratory Changes Oxidative Enzymes
-Response to regular endurance training include:
-Increase in the size and number of mitochondria in skeletal muscle
-Enhances the muscle's ability to use oxygen and produce ATP via oxidation
-Increase in the activity of the mitochondrial oxidative enzymes
-Slower rate of muscle glycogen utilization
-Enhanced reliance on fat as fuel at any given exercise intensity
-More significant as a result of resistance training than aerobic training.
-Occur in the early part of a strength-training program (1-3 weeks) before muscle hypertrophy occurs.
-Motor-unit recruitment and synchronization
- All-or-none principle: when activated, all muscle fibers in a motor unit contract maximally
-A motor unit produces varying levels of force depending on the frequency at which it is stimulated
-May increase with resistance training, resulting in increased frequency of discharge of the motor units and allowing trained muscles to reach peak force production more quickly.
-In opposing muscles, when maximizing force generated by the agonist, the activation of the antagonist must be diminished.
Hormonal Changes in Endurance Training
Generally, the hormonal response to a given exercise load declines with regular endurance training (signifying an increase in sensitivity or efficiency).
General Adaptation Syndrom (GAS)
GAS refers to body's predictable response to stressful events, including heavy exercise. 3 Stages
1. Shocker or Alarm phase (Usually lasts 2-3 weeks)
-The Individual initially exhibits signs of fatigue, weakness and soreness
-He or she soon experiences remarkable gains (Attributed to neural muscular adaptations.
2. Adaptation of resistance phase (Begins around 4-6 weeks)
-Major muscular adaptations (biochemical, mechanical, and structural)
-Progressive increases in muscle size and strength
3. Exhaustion phase (may occur at any time)
-Symptoms similar to the first phase, but in adequate repair or recovery time lead to burn out, over training, reduction or elimination of overload, injury, illness or lack of adherence.
Overtraining often occurs during periods of intense overload in which signs and symptoms are individualized and include a combination of both physiological and emotional factors.
-Soem signs and symptoms include: A decline in physical performance with continued training, elevated heart rate and blood lactate levels at a fixed submaximal work rate, weight loss, sleep distrubance, multiple colds or sore throats, irritability, restlessness, excitability, and/or anxiousness, loss of motivation and vigor, lack of mental concentration and focus, lack of appreciation for things normally enjoyable.
Best way to prevent over training is periodization.
Delayed Onset Muscle Soreness (DOMS)
How to reduce DOMS: starting at a low intensity and progressing slowly through the first few weeks while minimizing eccentric actions.
-Research suggests DOMS is caused by tissue injury from strenuous exercise
-Generally appears 24-48 hours after strenuous exercise
-Is thought to result from a series of events activated by strenuous exercise: First, structural damage occurs as a result of strenuous eccentric muscle actions. As a result, calcium is leaked out of the sarcoplasmic reticulum and collects in the mitochondria, halting ATP production. The build-up on calcium activates enzymes that break down proteins. The breakdown of proteins causes an inflammatory process.
Principle of Specificity
General Training principle
-The Exercise response to any training program is specific to the mode and intensity of training
Principles of Overload and Progression
General Training Principles
-Overload involves increasing the load on the tissue or system above and beyond the normal load.
-Progression is the systematic process of applying overload.
Principle of Diminishing Returns
General Training Principles
The rate of fitness improvement diminishes over time as an individual's fitness approaches its ultimate genetic potential.
Principle of Reversibility
General Training Principles
-When Training ceases, all gains will return to pretraining levels and may possibly decrease to the point where they are only supporting the demands of daily use.
After a prolonged period of resistance training, chronic hypertrophy is responsible for strength gains.
Results from one or more of the following: Increased number of myofibrils, increased number of actin and myosin flaments, more sarcoplasm and more connective tissue.
-Increased protein synthesis
-Eccentric actions combined with high-velocity training promote greater increases.
-Stress to the muscle stimulates the migration of satellite cells to the damaged region to fuel existing muscle fibers and/or produce new ones.
-In humans, most evidence points to muscle-fiber hypertrophy as the primary cause of increased muscle size associated with resistance training
Enhancing Muscle Growth through Exercise
A resistance-training program that stimulates protein synthesis (and Muscle Growth) increases levels of testosterone and growth hormone.
-Growth hormone increases availability of amino acids for protein synthesis and stimulates the release of IGF-1, which works with GH to stimulate muscle growth
-Testosterone promotes the release of GH and interact with neuromuscular system to stimulate muscle growth
-These responses are brought about by performing large-muscle group, multijoint exercises at high intensities with short rest intervals (30-60 seconds)
Muscle Glycogen Storage
-Appox 300-400 grams of glycogen is stored in skeletal muscles and approx 70-100 grams is stored in the liver.
-At intensities >60% VO2 max, muscle glycogen is the predominant fuel source. Liver glycogen is more important during low-intensity activity.
-Enhancing muscle glycogen storage involves eating a carbohydrate-rich diet and consuming carbs within 30 minutes at high-intensity exercise.
-It takes about 24 hours to restore muscle glycogen, if nutrient needs are met post-workout and the athlete was properly fueled prior to the workout.
Muscle-buffering capacity refers to the muscle's ability to neutralize the lactic acid that accumilates in them during high intensity activity.
-Delays the onset of fatigue
-Allows the exerciser to perform at a higher intesity and duration before "hitting the wall"
-Training at the lactate threshold will enhance buffering capacity and delay muscle fatigue for subsequent training sessions.
-Ventilatory threshold is an indirect representation of lactate threshold
-Endurance training improves the ability to sustain high levels of submaximal ventilation.
-Tissue properties affecting flexibility training:
-Mechanical property that allows tissue to return to its original shape or size when a force applied is removed (temporary deformation)
-A tissue reaches its "elastic limit" when it is stretched beyond the point where it cannot return to its normal length when tensile (Stretching) force is removed
-The difference between the original resting length and new resting length is called "permanent deformation".
-The new state of permanent elongation called "Plastic strength"
-Static stretching elongates tissue t point where deformation remains.
-Allows tissue to deform when it is loaded past its elastic limit.
-Once a tissue is set past yield point, tissue failure resulting in additional deformation may occur within small increases in force.
Viscosity allows tissues to resist loads and is dependent on time and temperature.
-With exposure to low loads, most tissues exhibit elastic behavior; exposure to higher loads cause tissue to exhibit a plastic response
Neurological Properties of Stretching I
Autogenic Inhibition: the activation of a golgi tendon organ (GTO) inhibits muscle spindle response.
-Initially, a low-force, long duration (Static) stretch stimulates low-grade muscle spindle activity and temporary increases in muscle tension.
-Muscle spindles become desensitized as the stretch continues (referred to as stress-relaxation).
-After 7-10 seconds, the increase in muscle tension activates the GTO response, inhibiting muscle spindle activity and further muscle stretching.
Neurological Properties of Stretching II
-Holding the stretch beyond 10 seconds stresses the collagen fibers, causing plastic deformation and lengthening the tissue (Creep)
-When the stretch ends, muscle spindles reestablish their threshold.
-Repeating the stretch a finite numbers of times produces a gradual increase in muscle extensibility.
Neorological prop of stretching
-Activating the muscle on one side of a joint (i.e. the antagonist) coincides with neural inhibition of the opposing muscle on the other side of the joint (i.e. the antagonist) to facilitate movement.
Ex: While performing a supine hamstring stretch, contraction of the hip flexor muscles on the leg being stretched will produce more active hip flexion, resulting in reciprocal inhibition of the hamstring muscle group, allowing them to be stretched further.
Involves moving the joints to place the targeted muscle group in an end-range position and holding that position for up to 30 seconds.
-Does not elicit the stretch reflex, reducing the risk of injury with proper technique
Proprioceptive Neuromuscular Facilitation (PNF)
PNF incorporates the principles of autogenic inhibition and reciprocal inhibition
-These are 3 types of PNF, all of which begin with passive (partner) 10 second pre-stretch
-Hold-relax with agonist contraction
-Mimics the movement pattern to be used in an upcoming workout
-Dynamic stretching is an effective component of a warm-up
-Incorporates bouncing-type movements
-Typically triggers the stretch-reflex, which increases the risk of injury
-Has a role in conditioning and training if done correctly.
Active Isolated Stretching (AIS)
AIS follows a design similar to a traditional strength training program
-Stretches, which never last longer than 2 seconds, are performed in sets, which each movement exceeding the risistance point of the prior stretch by a few degrees.
-Each set isolates an individual muscle
Myofascial release applies pressure too tight, restricted areas of fascia and underlying muscle in an attempt to relieve tension and improve flexibility
-It is thought that sustained pressure to a tight area can inhibit tension in a muscle by stimulating the GTO to bring about autogenic inhibition
-Trigger points can be diminished through app. of pressure by static stretching of the tight area
- In the fitness setting, a foam roller is used, allowing the exerciser to control his or her own intensity and duration of pressure.
Static Stretching & Permanent Tissue Elongation
static stretching- low force, long duration stretching at elevated tissue temperatures is more likely to result in plastic lengthening (compared to high force, short duration)
-Dynamic stretching can be used to warm muscles, and be followed by static stretching
-Static stretching most effective when performed during the cool down of training sessions
-Holding stretch 15-30 seconds appears most effective
-each stretch should be repeated 3-4 times
Calculation of Desired Body Weight
-Determine total body weight
-Determine amount of FM and FFM based on percentages of FFM and FM
-Determine appropriate desired body composition and total body weight
- Calculate new percentages of FM and FFM
Acute Responses to Exercise
-Going from rest to exercise requires the circulatory and respiratory system to increase oxygen delivery
-To meet the increased demands of the muscles, two major adjustments in blood flow occur.
-Redistribution of blood flow from the inactive organs to the active skeletal muscles.
-Increased cardiac output (Q=SV x HR)
Acute Response to Exercise II
-Regulation of heart rate is controlled:
-Intrinsically by the sinoatrial node (SA node)
-Extrinsically by the nervous and endocrine systems
-Changes in heart rate are influenced by the parasympathetic divisions of the autonomic nervous system (NS)
-ANS is not under conscious (voluntary) control
-portions of nervous system that control heart, visceral muscles, endocrine glands
Inherent Rhythm of the Heart
-Because of its specializing capacity, cardiac muscle is able to maintain its own rhythm
-The inherant rhythm of the heart is about 100 bpm and occurs because it can be innately stimulated via spontaneous deplorization and repolarization of the SA mode.
-Impulses that originateat the SA node spread to the atrioventricular node (AV node), causing the atria to contract together, then the ventricles to contract together.
-Parasympathetic fibers reach the heart via the vagus nerves, which will make contact at both the SA node and AN node
-When stimulated, vagus nerve endings will release acetylcholine, decreasing SA and AV node activity and reducing heart rate
-Sympathetic fibers connect to the heart via the cardiac accelerator nerves, which innervate the SA node and venticles
-When stimulated, epipephrine and norepinephrine are released, accelerating depolarization of the SA node and increasing heart rate and contractility
-"fight or flight"
-Rate (up to 100 bpm) is due to the withdrawal of prasympathetic tone.
Sympathetic Regulation II
-Increased cardiac output is influenced by:
-An increase in end diastolic volume, which causes a stretch in cardiac fibers, thereby creating a stronger force of contraction
-Stronger contradictility results in more blood pumped per beat (i.e. a greater stroke volume)
-Increased blood flow in the working muscles is a result of
Reason for increased blood flow to the working muscles
Vasoconstriction of the arteries supplying the viscera, which shifts blood from the abdominal organs to the working muscles
Vasconstriction of the vessels supplying non-working muscles (except the heart) and vasodilation of the vessels supplying the working muscles.
Reason for Increased blood flow to working muscles
The monitoring system of the effectiveness of blood flow in response to the accumulation of metabolites
Systolic Blood Pressure
Function of the force generated by the heart during its contraction phase (systole) and the resistance offered by the vessels to the blood flowing though them.
Systolic blood pressure is much higher because:
-Increased contractility of the heart
-Increased stroke volume
-The muscular need for greater force and pressure to deliver blood to the exercising muscles.
-Vasolidation within the excercising muscle, which results in more blood drained from arteries into muscle capillaries
Blood distribution during exercise
Exercise affects blood flow to various organ systems differently
ex: skeletal muscle recieves 15-20% of total cardiac output during rest, but 80-85% during maximal exercise
Blood volume is affected by the hydrostatic pressure of a muscle contraction, accumulation of metabolites and sweat
Body preserval of blood during exercise
By means of:
-Offsetting the small decrease in stroke volume by decreasing heart rate (during steady state exercise)
-Increasing vasoconstriction in non-working muscles to maintain peripheral resistance and blood pressure
-Releasing vasopressin and aldosterone to help reduce water and sodium loss
-During resistance training, the working muscles experience a temporary increase in fluid accumulation, which results in a feeling of fullness in the muscle (transient hypertrophy)
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