Transcript 7. Metabolic Adaptations to Exercise.

Metabolic Adaptations to Training
Chapter 5
 Aerobic
training:
– increases number of capillaries per muscle
fiber
– increases and the number of capillaries for a
given cross-sectional area of muscle
 Both
of these changes improve blood
perfusion in the muscles.
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Fiber Types
I – ST – Red – Aerobic – Fatigue
Resistant – Few Fibers per Motor Unit
 Type IIa – FTO – Pink – Anaerobic
w/aerobic capability
 Type IIb – FTG – White – Purely
Anaerbobic - Multiple Fibers per Motor
Unit – Power Fibers
 Type
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Response and Adaptation
 Endurance
training stresses ST muscle
fibers more than FT fibers.
 Result
- ST fibers enlarge with training.
 Hunters
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Response and Adaptation
 Percentages
of ST and FT fibers do not
appear to change
 Endurance
training causes Ftb fibers to take
on more Fta characteristics.
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Response and Adaptation
 Endurance
training increases muscle
myoglobin content by about 75% to 80%
 Myoglobin
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stores oxygen.
Response and Adaptation
 Endurance
training increases both the
number and the size of the mitochondria.
 Activities
of many oxidative enzymes are
increased with training.
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Response and Adaptation
 These
changes occurring in the muscles,
combined with adaptations in the oxygen
transport system, lead to enhanced
functioning of the oxidative system and
improved endurance.
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Fuel Storage
 Endurance-trained
muscle stores
considerably more glycogen than does
untrained muscle.
 Endurance-trained
muscle also stores more
fat (triglyceride) than does untrained
muscle.
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Fuel Storage
 The
activities of many enzymes involved in
b oxidation of fat increase with training,
thus free fatty acid levels increase.
 This
leads to increased use of fat as an
energy source, sparing glycogen.
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Training
 The
ideal training regimen should have a
caloric expenditure of a minimum of 2,000
to a maximum of about 5,000 to 6,000 kcal
per week.
 There
seems to be little benefit beyond this
level in consideration of the added risk of
injury.
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Training
 Intensity
is also a critical factor in
improving performance.
 Adaptations
are specific to the speed and
duration of training bouts, so those who
perform at higher intensities must train at
higher intensities.
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Training
 Aerobic
interval training involves repeated
bouts of high-intensity performance
separated by brief rest periods.
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Training
 This
training, although traditionally
considered only anaerobic, generates
aerobic benefits because the rest period is so
brief that full recovery can’t occur, thus the
aerobic system is stressed.
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Training
 Continuous
training is done as one
prolonged bout of exercise, some many
exercisers find it boring.
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Training
 The
aerobic benefits from both interval
training and continuous high-intensity
training seem to be about the same.
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Anaerobic Training
 Anaerobic
training bouts improve anaerobic
performance, but the improvement appears
to result more from strength gains than from
improvements in the functioning of the
anaerobic energy systems.
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Anaerobic Training
 Anaerobic
training also improves the
efficiency of movement, and more efficient
movement requires less energy expenditure.
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Anaerobic Training
 Although
sprint-type exercise is anaerobic
by nature, part of the energy used during
longer sprint bouts comes from oxidation,
so muscle aerobic capacity can also be
increased with this type of training.
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Anaerobic Training
 Muscle
buffering capacity is increased by
anaerobic training, allowing the
achievement of higher muscle and blood
lactate levels.
 This allows the H+ that dissociates from the
lactic acid to be neutralized, thus delaying
fatigue.
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Anaerobic Training
 Changes
in muscle enzyme activity are
highly specific to the type of training.
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