Transcript Chapter_10_4E - Ironbark (xtelco)

chapter
10
Adaptations to
Aerobic and
Anaerobic Training
Learning Objectives
• Learn how cardiorespiratory endurance differs from
muscular endurance
• Learn about the cardiorespiratory adaptations to
endurance training
• Find out what changes occur in the oxygen transport
system as a result of endurance training
(continued)
Learning Objectives (continued)
• Examine metabolic adaptations that occur with
endurance training
• Learn how cardiorespiratory and metabolic adaptations
benefit performance in both endurance and
nonendurance sports
(continued)
Learning Objectives (continued)
• Find out how training can maximize our energy
systems and our potential to perform
• Learn the differing adaptations that occur with aerobic
and anaerobic training
• Find out how specific types of aerobic and anaerobic
training can improve performance
Aerobic and Anaerobic Training
Aerobic (endurance) training
• Improved central and peripheral blood flow
• Enhances the capacity of muscle fibers to
generate ATP
Anaerobic training
• Increased short-term, high-intensity endurance
capacity
• Increased anaerobic metabolic function
• Increased tolerance for acid–base imbalances
during highly intense effort
Endurance
Muscular endurance: the ability of a single muscle or
muscle group to sustain high-intensity repetitive or
static exercise
Cardiorespiratory endurance: the entire body’s ability
to sustain prolonged, dynamic exercise using large
muscle groups
Evaluating Cardiorespiratory
Endurance
.
VO2max
• Highest rate of oxygen consumption attainable
during maximal exercise
.
• VO2max can be increased by 10-15% with 20
weeks of endurance training
.
Increases in VO2max
With Endurance Training
Fick equation:
.
VO2 = SV  HR  (a-v)O2 diff
.
Changes in VO2max With 12 Months
of Endurance Training
Cardiovascular Adaptation to Training
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Heart size
Stroke volume
Heart rate
Cardiac output
Blood flow
Blood pressure
Blood volume
Percentage Differences in Heart Size
Among Three Groups of Athletes
Compared With Untrained Group
Heart Size (Central) Adaptation
to Endurance Training
Key Points
• The left ventricle changes significantly in response
to endurance training
• The internal dimensions of the left ventricle
increase as an adaptation to an increase in
ventricular filling secondary to an increase in
plasma volume and diastolic filling time
• Left ventricular wall thickness and mass increase,
allowing for greater contractility
Measuring Heart Size:
Echocardiography
© Tom Roberts
Changes in Stroke Volume
With Endurance Training
Stroke Volume Adaptations
to Endurance Training
Key Points
• Endurance training increases SV at rest and during
submaximal and maximal exercise
• Increases in end-diastolic volume, caused by an
increase in blood plasma and greater diastolic
filling time (lower heart rate), contribute to
increased SV
• Increased ventricular filling (preload) leads to
greater contractility (Frank-Starling mechanism)
• Reduced systemic vascular resistance (afterload)
Heart Rate Adaptations
to Endurance Training
Resting
• Decreases by ~1 beat/min with each week of
training
• Increased parasympathetic (vagal) tone
Submaximal
• Decreases heart rate for a given absolute exercise
intensity
Maximal
• Unchanged or decreases slightly
Changes in Heart Rate
With Endurance Training
Heart Rate Recovery
• The time it takes the heart to return to its resting rate
after exercise
• Faster rate of recovery after training
• Indirect index of cardiorespiratory fitness
• Prolonged by certain environments (heat, altitude)
• Can be used as a tool to track the progress of
endurance training
Changes in Heart Rate Recovery
With Endurance Training
Cardiac Output Adaptations
to Endurance Training
.
Q = HR x SV
• Does not change at rest or during submaximal exercise
(may decrease slightly)
• Maximal cardiac output increases due largely to an
increase in stroke volume
Changes in Cardiac Output
With Endurance Training
Cardiac Output Adaptations
Key Points
.
• Q does not change at rest or during submaximal
exercise after training (may decrease slightly)
.
• Q increases at maximal exercise
. and is largely
responsible for the increase in VO2max
.
• Increased maximal Q results from the increase in
maximal SV
Blood Flow Adaptations
to Endurance Training
Blood flow to exercising muscle is increased with
endurance training due to:
• Increased capillarization of trained muscles
• Greater recruitment of existing capillaries in trained
muscles
• More effective blood flow redistribution from inactive
regions
• Increased blood volume
.
• Increased Q
Blood Pressure (BP) Adaptations
to Endurance Training
• Resting BP decreases in borderline and hypertensive
individuals (6-7 mmHg reduction)
• Mean arterial pressure is reduced at a given
submaximal exercise intensity (↓ SBP, ↓ DBP)
• At maximal exercise (↑ SBP, ↓ DBP)
Blood Volume (BV) Adaptations
to Endurance Training
• BV increases rapidly with endurance training
• Plasma volume increases due to:
– Increased plasma proteins (albumin)
– Increased antidiuretic hormone and aldosterone
• Red blood cell volume increases
• Hemoglobin increases
Increases in Total Blood Volume and
Plasma Volume With Endurance Training
Blood Flow, Pressure, and Volume
Adaptations to Endurance Training
Key Points
• Blood flow to active muscles is increased due to:
– ↑ Capillarization
– ↑ Capillary recruitment
– More effective redistribution
– ↑ Blood volume
• Blood pressure at rest as well as during
submaximal exercise is reduced, but not at
maximal exercise
(continued)
Blood Flow, Pressure, and Volume
Adaptations to Endurance Training
(continued)
Key Points
• Blood volume increases
• Plasma volume increases through increased
protein content and by fluid conservation hormones
• Red blood cell volume and hemoglobin increase
• Blood viscosity decreases due to the increase in
plasma volume
Respiratory Adaptations
to Endurance Training
Key Points
• Little effect on lung structure and function at rest
• Increase in pulmonary ventilation during maximal
exercise
• ↑ Tidal volume
• ↑ Respiratory rate
• Pulmonary diffusion increases at maximal exercise
due to increased ventilation and lung perfusion
• (a-v)O2 difference increases with training, reflecting
increased extraction of oxygen at the tissues
Adaptations in Muscle
to Endurance Training
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Increased size (cross-sectional area) of type I fibers
Transition of type IIx → type IIa fiber characteristics
Transition of type II → type I fiber characteristics
Increased number of capillaries per muscle fiber and for
a given cross-sectional area of muscle
• Increased myoglobin content of muscle by 75% to 80%
• Increased number, size, and oxidative enzyme activity
of mitochondria
Change in Maximal Oxygen Uptake and
SDH Activity With Endurance Training
Gastrocnemius Oxidative Enzyme
Activities of Untrained (UT) Subjects,
Moderately Trained (MT) Joggers,
and Highly Trained (HT) Runners
Adapted, by permission, from D.L. Costill et al., 1979, "Lipid metabolism in skeletal muscle of endurance-trained
males and females," Journal of Applied Physiology 28: 251-255 and from D.L. Costill et al., 1979, "Adaptations in
skeletal muscle following strength training," Journal of Applied Physiology 46: 96-99.
Adaptations in Muscle With Training
Key Points
• Type I fibers tend to enlarge
• Increase in type I fibers and a transition from type IIx
to type IIa fibers
• Increased number of capillaries supplying each
muscle fiber
• Increase in the number and size of muscle fiber
mitochondria
• Oxidative enzyme activity increases
• Increased capacity of oxidative metabolism
Metabolic Adaptations to Training
• Lactate threshold increases due to:
– Increased clearance and/or decreased
production of lactate
– Reduced reliance on glycolytic systems
• Respiratory exchange ratio decreases due to:
– Increased utilization of free fatty acids
.
• Oxygen consumption (VO2)
– Unchanged (or slightly reduced) at submaximal
intensities
.
– VO2max increases
– Limited by the ability of the cardiovascular
system to deliver oxygen to active muscles
Changes in Lactate Threshold
With Training
(continued)
(continued)
Changes in Race
. Pace With Continued
Training After VO2max Stops Increasing
Increased
Performance
.
After VO2max Has Peaked
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
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VO2max for extended periods. The increase
in
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performance without an increase in VO2max is a result
of an increase in lactate threshold.
.
Factors Affecting VO2max
Level of conditioning:
. Initial state of conditioning will
determine how much VO2max will increase (i.e., the
higher the initial value, the smaller the expected
increase)
Heredity: Accounts for 25-50% of the variation in
VO2max
Sex: Women have lower VO2max compared to men
Individual responsiveness: There are high responders
and low responders to endurance training, which is a
genetic phenomenon
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Comparisons of VO2max in Twins
and Nontwin Brothers
Adapted, by permission, from C. Bouchard et al., 1986, “Aerobic performance in brothers, dizygotic and monozygotic
twins,” Medicine and Science in Sports and Exercise 18: 639-646.
(continued)
(continued)
Variations
. in the Percentage Increase
in VO2max for Identical Twins
From D. Prud'homme et al., 1984, “Sensitivity of maximal aerobic power to training is genotype-dependent,”
Medicine and Science in Sports and Exercise 16(5): 489-493. Copyright 1984 by American College of Sports
Medicine. Adapted by permission.
.
Variations in the Improvement in VO2max
Following 20 Weeks of Endurance Training
.
Adapted, by permission, from C. Bouchard et al., 1999, “Familial aggregation of VO 2max response to exercise
training: Results from HERITAGE Family Study,” Journal of Applied Physiology 87: 1003-1008.
Cardiorespiratory Endurance
and Performance
• It is the major defense against fatigue
• Should be the primary emphasis of training for health
and fitness
• All athletes can benefit from maximizing their endurance
Adaptations to Aerobic Training
Key Points
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Although VO2max has an upper limit, endurance
performance can continue to improve
An individual’s. genetic makeup predetermines a range
for his or her. VO2max and accounts for 25-50% of the
variance in VO2max
Heredity largely explains an individual’s response to
training
Highly
conditioned female endurance athletes have
.
VO2max values about 10% lower than their male
counterparts
All athletes can benefit from maximizing their
cardiorespiratory endurance
Summary of Cardiovascular Adaptation
to Chronic Endurance Training
Adapted, by permission, from Donna H. Korzick, Pennsylvania State University, 2006.
Muscle Adaptations
to Anaerobic Training
• Increased muscle fiber recruitment
• Increased cross-sectional area of type IIa and type IIx
muscle fibers
Energy System Adaptations
to Anaerobic Training
• Increased ATP-PCr system enzyme activity
• Increased activity of several key glycolytic enzymes
• No effect on oxidative enzyme activity
Changes in Creatine Kinase (CK)
and Myokinase (MK) Activities
With Anaerobic Training
Performance in a 60 s Sprint Bout
After Anaerobic Training
Anaerobic Training
Key Points
• Anaerobic training bouts improve both anaerobic power
and anaerobic capacity
• Increased performance with anaerobic training is
attributed to strength gains
• Increases ATP-PCr and glycolytic enzymes
Specificity of Training
and Cross-Training
• To maximize cardiorespiratory gains from training, the
training should be specific to the type of activity that the
athlete usually performs
• Cross-training is training for more than one sport at a
time
• Gains in muscular strength and power are less when
strength training is combined with endurance training
.
VO2max Values During Uphill Treadmill
Running vs. Sport-Specific Activities in
Selected Groups of Athletes
Adapted, by permission, from S.B. Strømme, F. Ingjer, and H.D. Meen, 1977, “Assessment of maximal aerobic
power in specifically trained athletes,” Journal of Applied Physiology 42: 833-837.