Transcript No Slide Title

Acute Responses vs Chronic Adaptations
Acute responses to training involve how the body
responds to one bout of exercise.
Chronic physiological adaptations to training mark how
the body responds over time to the stress of repeated
exercise bouts.
Key Points
Acute Responses to Exercise
w Control environmental factors such as
temperature, humidity, light, and noise.
w Account for diurnal cycles, menstrual
cycles, and sleep patterns.
w Use ergometers to measure physical work
in standardized conditions.
w Match the mode of testing to the type of
activity the subject usually performs.
Basic Training Principles
Individuality—Consider the specific needs and abilities of
the individual.
Specificity—Stress the physiological systems critical for
the specific sport.
Disuse—Include a program to maintain fitness.
Progressive overload—Increase the
training stimulus as the body adapts.
Hard/easy—Alternate high-intensity
with low-intensity workouts.
Periodization—Cycle specificity,
intensity, and volume of training.
Measuring Muscular Performance
Strength—the maximal force a muscle or muscle group
can generate.
Power—the product of strength and the speed of
movement.
Muscular endurance—the capacity to sustain repeated
muscle actions.
Muscular Endurance
w Can be evaluated by noting the number of repetitions you
can perform at a given percentage of your 1-RM
w Is increased through gains in muscular strength
w Is increased through changes in local metabolic and
circulatory function
Key Points
Terminology
w Muscular strength is the maximal amount
of force a muscle or group of muscles can
generate.
w Muscular power is the product of strength
and speed of the movement.
w Though two individuals can lift the same
amount of weight, if one can lift it faster,
she is generating more power than the
other.
w Muscular endurance is the ability of a
muscle to sustain repeated muscle actions
or a single static action.
Did You Know…?
Resistance training programs can produce a 25% to
100% improvement in strength within 3 to 6 months.
Results of Resistance Training
w Increased muscle size (hypertrophy).
w Alterations of neural control of trained muscle.
w Studies show strength gains can be achieved without
changes in muscle size, but not without neural
adaptations.
Possible Neural Factors of Strength Gains
w Recruitment of additional motor units for greater force
production
w Counteraction of autogenic inhibition allowing greater
force production
w Reduction of coactivation of agonist and antagonist
muscles
w Changes in the discharge rates of motor units
w Changes in the neuromuscular junction
Muscle Hypertrophy
Transient—pumping up of muscle during a single exercise
bout due to fluid accumulation from the blood plasma into
the interstitial spaces of the muscle.
Chronic—increase of muscle size after long-term
resistance training due to changes in muscle fiber number
(fiber hyperplasia) or muscle fiber size (fiber hypertrophy).
Fiber Hypertrophy
w The numbers of myofibrils and actin and myosin filaments
increase, resulting in more cross-bridges.
w Muscle protein synthesis increases during the
postexercise period.
w Testosterone plays a role in promoting muscle growth.
w Training at higher intensities appears to cause greater fiber
hypertrophy than training at lower intensities.
Fiber Hyperplasia
w Muscle fibers split in half with intense weight training.
w Each half then increases to the size of the parent fiber.
w Satellite cells may also be involved in skeletal muscle
fiber generation.
w It has been clearly shown to occur in animal models;
only a few studies show this occurs in humans too.
Neural Activation and Fiber Hypertrophy
w Early gains in strength appear to be more influenced by
neural factors.
w Long-term strength increases are largely the result of
muscle fiber hypertrophy.
MODEL OF NEURAL AND
HYPERTROPHIC FACTORS
Key Points
Resistance Training
w Neural adaptations always accompany
strength gains from resistance training;
hypertrophy may or may not be present.
w Transient hypertrophy results from short-
term increases in muscle size due to fluid
in the muscle.
w Chronic muscle hypertrophy results from
long-term training and is caused by
structural changes in the muscle.
(continued)
Key Points
Resistance Training
w Muscle hypertrophy is most clearly due to
increases in fiber size, but also may be
due to increases in the number of fibers.
w Muscle atrophy occurs when muscles are
inactive; however, a planned reduction in
training can maintain muscle size and
strength for a period of time.
w A muscle fiber type can take on
characteristics of the opposite type in
response to training. Cross-innervation or
chronic stimulation of fibers may convert
one fiber type into another fiber type.
Aerobic vs Anaerobic Training
Aerobic (endurance) training leads to
w Improved blood flow, and
w Increased capacity of muscle fibers to
generate ATP.
Anaerobic training leads to
w Increased muscular strength, and
w Increased tolerance for acid-base imbalances
during highly intense effort.
Adaptations to Aerobic Training
.
w Improved submaximal aerobic endurance and VO2max
w Muscular changes in fiber size, blood and oxygen supply,
and efficiency of functioning
w Improved efficiency of energy production
w The magnitude of these changes depend on
genetic factors
Muscular Adaptations
w Increased cross-sectional area of ST fibers
w Small transition of FTb to FTa fibers, but there can
also be a small transition of FT to ST fibers
w Increased number of capillaries supplying the muscles
which
likely is an important factor that allows increase in
.
VO2max
w Increased myoglobin content of muscle by 75% to 80%
(allowing muscle to store more oxygen)
w Increased number, size, and oxidative enzyme activity of
mitochondria
CAPILLARIZATION IN MUSCLES
Untrained
Trained
CHANGE IN SDH ACTIVITY
LEG MUSCLE ENZYME ACTIVITIES
Adaptations Affecting Energy Sources
w Trained muscles store more glycogen and triglycerides
than untrained muscles.
w FFAs are better mobilized and more accessible to trained
muscles.
w Muscles’ ability to oxidize fat increases with training.
w Muscles’ increased reliance on fat stores
conserves glycogen during prolonged
exercise.
MITOCHONDRIA (A), GLYCOGEN (B),
AND TRIGLYCERIDES (C)
USE OF ENERGY SOURCES WITH
INCREASING INTENSITY
.
.
QO2 vs VO2max
.
QO2 measures the maximal respiratory or oxidative capacity
of muscle.
.
VO2max measures the body's maximal oxygen uptake.
.
.
QO2 AND VO2MAX WITH TRAINING
Key Points
Adaptations to Aerobic Training
w Aerobic training stresses ST fibers more
than FT fibers and causes ST fibers to
increase in size.
w Prolonged aerobic training may cause FTb
fibers to take on characteristics of FTa
fibers, and in some cases a small
percentage of ST fibers become FT fibers.
w The number of capillaries supplying each
muscle fiber increases with training.
w Myoglobin (which stores oxygen) content
increases in muscle by about 75% to 80%
with aerobic training.
(continued)
Key Points
Adaptations to Aerobic Training
w Aerobic training increases the number and
size of mitochondria and the activities of
oxidative enzymes.
w Endurance-trained muscle stores more
glycogen and triglyceride than untrained
muscle.
w Increased fat availability and capacity to
oxidize fat lead to increased use of fat as
an energy source, sparing glycogen.
Aerobic Training Considerations
Volume
w Frequency of exercise bouts
w Duration of each exercise bout
Intensity
w Interval training
w Continuous training
Training Volume
w Volume is the load of training in each training session
and over a given period of time.
w Adaptations to given volumes vary from individual
to individual.
w An ideal aerobic training volume appears to be equivalent
to an energy expenditure of about 5,000 to 6,000 kcal per
week.
w Athletes who train with progressively greater volumes
eventually reach a maximal level of improvement beyond
which additional
. training volume will not improve
endurance or VO2max.
.
TRAINING VOLUME AND VO2MAX
Training Intensity
w Muscular adaptations are specific to the speed as well as
duration of training.
w Athletes who incorporate high-intensity speed training
show more performance improvements than athletes who
perform only long, slow, low-intensity training.
w Aerobic intervals are repeated, fast-paced, brief exercise
bouts followed by short rests.
w Continuous training involves one continuous, highintensity exercise bout.
Key Points
Training the Aerobic System
w Ideal aerobic training volume is equivalent
to a caloric expenditure of 5,000 to 6,000
kcal per week.
w To perform at higher intensities, athletes
must train at higher intensities.
w Aerobic interval training—repeated bouts
of short, high-intensity performance
followed by short rest periods—and
continuous training—one prolonged, highintensity bout—both generate aerobic
benefits.
Selected Muscle Enzyme Activities
(mmol . g-1 . min-1) for Untrained, Anaerobically
Trained, and Aerobically Trained Men
Aerobic enzymes
Oxidative system
Succinate dehydrogenase
Malate dehydrogenase
Carnitine palmityl transferase
Anaerobic enzymes
ATP-PCr system
Creatine kinase
Myokinase
Glycolytic system
Phosphorylase
Phosphofructokinase
Lactate dehydrogenase
a
Untrained
Anaerobically
trained
8.1
45.5
1.5
8.0
46.0
1.5
609.0
309.0
702.0 a
350.0 a
589.0
297.0
5.3
19.9
766.0
5.8
29.2 a
811.0
3.7 a
18.9
621.0
Denotes a significant difference from the untrained value.
Aerobically
trained
20.8 a
65.5 a
2.3 a
Major Cardiovascular Functions
w Delivery (e.g., oxygen and nutrients)
w Removal (e.g., carbon dioxide and waste products)
w Transportation (e.g., hormones)
w Maintenance (e.g., body temperature, pH)
w Prevention (e.g., infection—immune function)
Myocardium—Cardiac Muscle
w Thickness varies directly with stress placed on chamber
walls.
w Left ventricle is the most powerful of chambers and thus,
the largest.
w With vigorous exercise, the left ventricle size increases.
w Due to intercalated disks—impulses travel quickly in
cardiac muscle allowing rapid contraction.
Extrinsic Control of the Heart
w Parasympathetic nervous system acts through the vagus
nerve to decrease heart rate and force of contraction
(predominates at rest—vagal tone).
w Sympathetic nervous system is stimulated by stress to
increase heart rate and force of contraction.
w Epinephrine and norepinephrine—released due to
sympathetic stimulation—increase heart rate.
Did You Know…?
Resting heart rates in adults tend to be between 60 and 85
beats/min. However, extended endurance training can lower
resting heart rate to 35 beats/min or less. This lower heart
rate is thought to be due to decreased intrinsic heart rate
and increased parasympathetic stimulation.
Did You Know…?
The decrease in resting heart rate that occurs as an
adaptation to endurance training is different from
pathological bradycardia, an abnormal disturbance in the
resting heart rate.
Key Points
Structure and Function of the
Cardiovascular System
w The two atria receive blood into the heart;
the two ventricles send blood from the
heart to the rest of the body.
w The left ventricle has a thicker myocardium
due to hypertrophy resulting from the
resistance against which it must contract.
w Cardiac tissue has its own conduction
system through which it initiates its own
pulse without neural or hormonal control.
(continued)
Key Points
Structure and Function of the
Cardiovascular System
w The pacemaker of the heart is the SA
node; it establishes heart rate and
coordinates conduction.
w The autonomic nervous system or the
endocrine system can alter heart rate and
contraction strength.
w An ECG records the heart's electrical
function and can be used to detect cardiac
disorders.
WIGGERS DIAGRAM—CARDIAC CYCLE
Stroke Volume and Cardiac Output
Stroke Volume (SV)
w Volume of blood pumped per contraction
w End-diastolic volume (EDV)—volume of blood in ventricle
before contraction
w End-systolic volume (ESV)—volume of blood in ventricle
after contraction
w SV = EDV – ESV
.
Cardiac Output (Q)
w Total volume of blood pumped by the ventricle per minute
.
w Q = HR  SV
Ejection Fraction (EF)
w Proportion of blood pumped out of the left ventricle each
beat
w EF = SV/EDV
w Averages 60% at rest
CALCULATIONS .
OF SV, EF, AND Q
Vascular System
w Arteries
w Arterioles
w Capillaries
w Venules
w Veins
Blood Distribution
w Matched to overall metabolic demands
w Autoregulation—arterioles within organs or tissues dilate
or constrict in response to the local chemical environment
w Extrinsic neural control—sympathetic nerves within walls
of vessels are stimulated causing vessels to constrict
w Determined by the balance between mean arterial
pressure and total peripheral resistance
BLOOD
DISTRIBUTION
AT REST
Blood Pressure
w Systolic blood pressure (SBP) is the highest pressure and
diastolic blood pressure (DBP) is the lowest pressure
w Mean arterial pressure (MAP)—average pressure exerted
by the blood as it travels through arteries
w MAP = DBP + [0.333  (SBP – DBP)]
w Blood vessel constriction increases blood pressure;
dilation reduces blood pressure
Key Points
Vascular System
w Blood returns to the heart with the help of
breathing, the muscle pump, and valves in
the veins.
w Blood is distributed throughout the body
based on the needs of tissues; the most
active tissues receive the most blood.
w Autoregulation controls blood flow by
vasodilation in response to local chemical
changes in an area.
(continued)
Key Points
Vascular System
w Extrinsic neural factors control blood flow
primarily by vasoconstriction.
w Systolic blood pressure (SBP) is the
highest pressure within the vascular
system while diastolic blood pressure
(DBP) is the lowest.
w Mean arterial pressure (MAP) is the
average pressure on the arterial walls.
Cardiovascular Response to Acute Exercise
w Heart rate (HR) increases as exercise intensity increases
up to maximal heart rate.
.
w Stroke volume (SV) increases up to 40% to 60% VO2max
in untrained individuals and up to maximal levels in trained
individuals.
w Increases
. in HR and SV during exercise cause cardiac
output (Q) to increase.
w Blood flow and blood pressure change.
w All result in allowing the body to efficiently meet the
increased demands placed on it.
Resting Heart Rate
w Averages 60 to 80 beats/min; can range from 28 to above
100 beats/min
w Tends to decrease with age and with increased
cardiovascular fitness
w Is affected by environmental conditions such as altitude
and temperature
Maximum Heart Rate
w The highest heart rate value one can achieve in an all-out
effort to the point of exhaustion
w Remains constant day to day and changes slightly from
year to year
w Can be estimated: HRmax = 220 – age in years or
HRmax = 208 – (0.7  age)
HEART RATE AND INTENSITY
Steady-State Heart Rate
w Heart rate plateau reached during constant rate of
submaximal work
w Optimal heart rate for meeting circulatory demands at that
rate of work
w The lower the steady-state heart rate, the more efficient
the heart
Stroke Volume
w Determinant of cardiorespiratory endurance capacity at
maximal rates of work
w Increases with increasing rates of work up to intensities of
40% to 60% of max or higher
w May continue to increase up through maximal exercise
intensity, generally in highly trained athletes
w Magnitude of changes in SV depends on
position of body during exercise
STROKE VOLUME AND INTENSITY
Stroke Volume Increases During Exercise
w Frank Starling mechanism—more blood in the ventricle
causes it to stretch more and contract with more force.
w Increased ventricular contractility (without end-diastolic
volume increases).
w Decreased total peripheral resistance due to increased
vasodilation of blood vessels to active muscles.
.
CHANGES IN Q AND SV WITH
INCREASING RATES OF WORK
Cardiac Output
w Resting value is approximately 5.0 L/min.
w Increases directly with increasing exercise intensity to
maximal values of between 20 to 40 L/min.
w The magnitude of increase varies with body size and
endurance conditioning.
w When exercise
. intensity exceeds 40% to 60%, further
increases in Q are more a result of increases in HR than
SV since SV tends to plateau at higher work rates.
CARDIAC OUTPUT AND INTENSITY
.
RELATIVE DISTRIBUTION OF Q DURING
EXERCISE
.
ABSOLUTE DISTRIBUTION OF Q DURING
EXERCISE
Blood Pressure
Cardiovascular Endurance Exercise
w Systolic BP increases in direct proportion to increased
exercise intensity
w Diastolic BP changes little if any during endurance
exercise, regardless of intensity
Resistance Exercise
w Exaggerates BP responses to as high as 480/350 mmHg
w Some BP increases are attributed to the Valsalva
maneuver
BLOOD PRESSURE RESPONSES
Key Points
Cardiovascular Response
to Exercise
w As exercise intensity increases, heart rate,
stroke volume, and cardiac output increase
to get more blood to the active tissues.
w More blood pumped from the heart per
minute during exercise allows for more
oxygen and nutrients to get to the muscles
and for waste to be removed more quickly.
w Blood flow distribution changes from rest to
exercise as blood is redirected to the
muscles and systems that need it.
(continued)
Key Points
Cardiovascular Response
to Exercise
w Cardiovascular drift is the result of
decreased stroke volume, increased heart
rate, and decreased systemic and
pulmonary arterial pressure due to
prolonged steady-state exercise or
exercise in the heat.
w Systolic blood pressure increases directly
with increased aerobic exercise intensity
while diastolic blood pressure remains
constant.
w Blood pressure tends to increase during
high-intensity resistance training, due in
part to the Valsalva maneuver.
Arterial-Venous Oxygen Difference
w Amount of oxygen extracted from the blood as it travels
through the body
w Calculated as the difference between the oxygen content
of arterial blood and venous blood
w Increases with increasing rates of exercise as more
oxygen is taken from blood
w The Fick equation represents .the relationship of the
body’s oxygen consumption (VO2), to the arterial-venous
.
oxygen
(a-vO2 diff) and cardiac output (Q);
.
. difference
VO = Q  a-vO diff
2
2
–
CHANGES IN a-vO2 diff
Blood Plasma Volume
w Reduced with onset of exercise (goes to interstitial fluid
space)
w More is lost if exercise results in sweating
w Excessive loss can result in impaired performance
w Reduction in blood plasma volume
results in hemoconcentration
Key Points
Blood Changes During Exercise
- diff increases as venous oxygen
w The a-vO
2
concentration decreases during exercise
due to the body extracting oxygen from the
blood.
w Plasma volume decreases during exercise
due to water being drawn from the blood
plasma and out of the body as sweat.
w Hemoconcentration occurs. Plasma
volume is lost resulting in a higher
concentration of red blood cells per unit of
blood and, thus, increased oxygen-carrying
capacity.
w Blood pH decreases due to increased
blood lactate accumulation with increasing
exercise intensity.
Endurance Training
Muscular Endurance
w Ability of a single muscle or muscle group to sustain highintensity, repetitive, or static exercise that occurs in
repeated 1- to 2-minute bursts
w Related to muscular strength and anaerobic development
Cardiorespiratory Endurance
w Ability of the whole body to sustain
prolonged, steady-state exercise
w Related to cardiovascular and respiratory
system (aerobic) development
Evaluating Endurance Capacity
.
VO2max
w Highest rate of oxygen consumption attainable during
maximal exercise
w Can be increased with endurance training
Submaximal Endurance Capacity
w Closely related .to competitive endurance performance;
determined by VO2max and lactate threshold
w More difficult to evaluate since there is no one
physiological variable that can be measured to quantify it
w Can also be increased with endurance training
.
CHANGES IN VO2MAX WITH TRAINING
Parameters Affected by Training
w Heart size
w Stroke volume
w Heart rate
w Cardiac output
w Blood flow
w Blood pressure
w Blood volume
Oxygen Transport System
w Components of the cardiorespiratory system that
transport O2 to and from active tissues
w Evaluated
with the Fick equation:
.
– diff
VO2 = SV  HR  a-vO
2
w Can transport O2 more efficiently with adaptations
that occur with endurance training
DIFFERENCES IN HEART SIZE
DIFFERENCES IN HEART SIZE
DIFFERENCES IN HEART SIZE
Key Points
Heart Size Adaptations
w The left ventricle changes the most in
response to endurance training.
w The internal dimensions of the left ventricle
increase mostly due to an increase in
ventricular filling.
w The wall thickness of the left ventricle
increases, allowing a more forceful
contraction of the left ventricle.
STROKE VOLUME AND TRAINING
Stroke Volumes (SV) for
Different States of Training
Subjects
SVrest (ml)
SVmax (ml)
Untrained
50-70
80-110
Trained
70-90
110-150
Highly trained
90-110
150-220
DIFFERENCES IN EDV, ESV, AND EF
Key Points
Stroke Volume Adaptations
w Endurance training increases SV at rest
and during submaximal and maximal
exercise.
w End diastolic volume increases, caused by
an increase in blood plasma and greater
diastolic filling time, contributing to
increased SV.
w The increased size of the heart allows the
left ventricle to stretch more and fill with
more blood; wall thickness increases
enhance contractility. Reduced systemic
blood pressure lowers the resistance to the
flow of blood pumped from the left
ventricle.
HEART RATE AND TRAINING
Resting Heart Rate
w Decreases with endurance training likely due to more
blood returning to heart and changes in autonomic control
w Sedentary individuals can decrease RHR by 1 beat/min
per week during initial training, but several recent studies
have shown small changes of less than 3 beats/min with
up to 20 wk of training
w Highly trained endurance athletes may have resting heart
rates of 30 to 40 beats/min
Heart Rate During Exercise
Submaximal
w Decreases proportionately with the amount of training
completed
w May decrease by 10 to 30 beats/min after 6 months
of moderate training at any given rate of work, with the
decrease being greater at higher rates of work
Maximal
w Remains unchanged or decreases slightly
w A decrease might allow for optimal stroke volume to
maximize cardiac output
Which Comes First?
Does increased stroke volume allow a decreased heart rate
or does decreased heart rate allow an increased stroke
volume?
Heart Rate Recovery Period
w The time after exercise that it takes your heart to return to
its resting rate
w With training, heart rate returns to resting level more
quickly after exercise
w Has been used as an index of cardiorespiratory fitness
w Conditions such as altitude or heat can affect it
w Should not be used to compare individuals
to one another
HEART RATE RECOVERY AND TRAINING
Did You Know…?
Resistance training can lead to decreases in heart rate;
however, these decreases are not as reliable or as large as
those that occur due to endurance training.
Key Points
Cardiac Output Adaptations
.
w Q decreases slightly or does not change at
rest or during submaximal exercise.
w A slight decrease could be the result of an
– diff due to greater
increase in the a-vO
2
oxygen extraction by the tissues or to a
reduction in the requirement for oxygen.
.
w Q increases dramatically at maximal
exertion due to the increase in maximal SV.
.
w Absolute values of Qmax range from 14 to
20 L/min in untrained people, 25 to 35
L/min in trained individuals, and 40 L/min
or more in large endurance athletes.
CARDIAC OUTPUT AND TRAINING
Blood Flow Increases With Training
w Increased capillarization of trained muscles (higher
capillary-to-fiber ratio)
w Greater opening of existing capillaries in trained muscles
w More effective blood redistribution—blood goes where
it is needed
w Increased blood volume
Key Points
Blood Pressure and Training
w Endurance training results in reduced
blood pressure at the same submaximal
work rate, but at maximal work rates
systolic pressure increases and diastolic
pressure decreases.
w Resting blood pressure (both systolic and
diastolic) is lowered with endurance
training in individuals with borderline or
moderate hypertension.
w Blood pressure during lifting heavy weights
can cause marked increases in systolic
and diastolic blood pressure, but resting
blood pressure after resistance training
tends to not change and may decrease.
Key Points
Blood Volume and Training
w Endurance training, especially intense
training, increases blood volume.
w Blood volume increases due primarily to an
increase in plasma volume (increases in
ADH, aldosterone, and plasma proteins
cause more fluid to be retained in the blood).
w Red blood cell volume increases, but
increase in plasma volume is higher; thus,
hematocrit decreases.
w Blood viscosity decreases, thus improving
circulation and enhancing oxygen delivery.
w Changes in plasma volume are highly
.
correlated with changes in SV and VO2max.
Cardiovascular Adaptations to Training
w Left ventricle size and wall thickness increase
w Resting, submaximal, and maximal stroke volume increases
w Maximal heart rate stays the same or decreases
w Cardiac output is better distributed to active muscles and
maximal cardiac output increases
w Blood volume increases, as does red cell
volume, but to a lesser extent
w Resting blood pressure does not
change or decreases slightly, while
blood pressure during submaximal
exercise decreases
Key Points
Respiratory Adaptations to Training
w Pulmonary ventilation increases during
maximal effort after training; you can
improve performance by training the
inspiratory muscles.
w Pulmonary diffusion increases at maximal
work rates.
–
w The a-vO diff increases with training due
2
to more oxygen being extracted by tissues.
w The respiratory system is seldom a limiter
of endurance performance.
w All the major adaptations of the respiratory
system to training are most apparent
during maximal exercise.
Did You Know…?
.
Although the largest part of the increase in VO2max
results from the increases in cardiac output and muscle
–
blood flow, the increase in a-vO2 diff also plays a key
–
role. This increase in a-vO2 diff is due to a more effective
distribution of arterial blood away from inactive tissue to
the active tissue, so that more of the blood coming back
to the right atrium has gone through active muscle.
Metabolic Adaptations to Training
Lactate threshold increases.
Respiratory exchange ratio
w decreases for submaximal efforts (greater use of FFAs),
and
w increases at maximal levels.
.
Oxygen consumption (VO2) is
w unaltered or slightly increased at rest,
w unaltered or slighted decreased at submaximal rates of
work, and
.
w increased at maximal exertion (VO2max—increases range
from 0% to 93%).
Did You Know…?
Once .an athlete has achieved her genetically determined
peak VO2max, she can still increase her endurance
performance due to the body's ability to .perform at
increasingly higher percentages of that VO2max for
extended periods.
. The increase in performance without
an increase in VO2max is a result of an increase in
lactate threshold.
.
Factors Affecting VO2max
Level of conditioning—the greater the level of conditioning
the lower the response to training
Heredity—accounts for slightly less than 50% of the
variation as well as an individual’s response to training
Age—decreases with age are associated with decreases in
activity levels as well as decreases in physiological function
Sex—lower in women than men (20% to 25% lower in
untrained women; 10% lower in highly trained women)
Specificity of training—the closer training is to the sport to
be performed, the greater the improvement and
performance in that sport
.
VO2MAX CHANGES AND AGE
.
IMPROVEMENT IN VO2MAX WITH
TRAINING
MODELING ENDURANCE
PERFORMANCE