fmd2- k30 - fs_exercise physiology

8/19/2019 FMD2- K30 - FS_Exercise Physiology

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EXERCISE PHYSIOLOGY

Department of Physiology

Faculty of Medicine

Universitas Sumatera utara


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Systemic Responses toExercise


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NEUROMUSCULAR FUNCTIONS AND

ADAPTATIONS TO EXERCISE

Exercise maintains neuronal health by improving

blood flow to the brain and by increasing brain

levels of growth factors that promote optimal

function of neurons.

Recent study in humans has concluded that

exercise improves brain function and reduces the

risk of cognitive impairment associated with

aging.


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NEUROMUSCULAR FUNCTIONS AND


Humans skeletal muscle can be divided into

several different classes based on the

histochemical or biochemical characteristics of

the individual fibers.

Neural adaptations: ↑ maximal motor unit recruitment

↑ synchronous recruitment of motor units


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SO motor units are recruited first during

incremental exercise, followed by a progressive

increase in FOG and FG motor unit recruitment

as exercise intensity increases.

Both endurance and resistance exercise training

have been shown to promote a fast-to-slow shift

in skeletal muscle fiber types but does not result

in complete transformation of all fast fibers.

Training adaptations: increases in muscle size

from hypertrophy and hyperplasia.


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METABOLIC RESPONSES TO EXERCISE:

INFLUENCE OF DURATION AND INTENSITY

Short-term, Intense Exercise

• During high-intensity, short-term exercise (i.e.,

two to twenty seconds), the muscles’ ATP

production is dominated by the ATP-PS system.

• Intense exercise lasting more than twenty

seconds relies more on anaerobic glycolysis to

produce much of the needed ATP.

• High-intensity events lasting longer than forty-

five seconds use a combination of the ATP-PC

system, glycolysis, and the aerobic system to

produce the needed ATP for muscular

contraction.


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Prolonged Exercise

The energy to perform prolonged exercise (i.e.,

more than ten minutes) comes primarily from

aerobic metabolism.

A steady-state O2uptake can generally be

maintained during prolonged, low-intensity

exercise.


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Incremental Exercise

• The maximal capacity to transport and utilize O2

during exercise (maximal oxygen uptake, or

VO2 max) is considered to be the most valid

measurement of cardiovascular fitness.

• Indeed,incremental exercise test(also called

graded exercise test) are often employed to

determine a subject’s cardiovascular fitness.

• These tests are usually conducted on a treadmill

or a cycle ergometer.


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• Oxygen uptake increase in linear fashion during

incremental exercise until VO2 max is reached.

• The physiological factors that influence VO2 max

include: – The maximum ability of the cardiorespiratory system

to deliver oxygen to the contracting muscle.

– The muscle’s ability to take up the oxygen and

produce ATP aerobically.


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CARDIOVASCULAR FUNCTIONS AND


With the start of exercise, cardiovascular

function changes by:↑ Heart rate

↑ Ejection fraction

↑ Stroke volume

↑ Cardiac output

↑ Redistribution of Q in favor of contracting skeletal

muscle

↓ Vascular resistance↑ Muscle blood flow


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MuscleContraction

Venous Return

End Diastolic Volume

Contractility

Stroke Volume Heart

Rate

Cardiac Output

Cellular

Respiration

SympatheticStimulation

Muscle Vascular

Resistance

Muscle Blood

Flow

a-

vO2∆

Oxygen

Extraction

Oxygen

Consumption

Acute cardiovascularadaptations thatcombine to increaseoxygen consumptionduring exercise


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CARDIOVASCULAR FUNCTIONS AND


Cardiovascular adaptations to training are

extremely important for improving endurance

exercise performance, and preventing

cardiovascular disease

The more important of these adaptations are:↑ Plasma volume

↑ Red cell mass

↑ Total blood volume

↓ Systolic and diastolic blood pressure↑ End diastolic dimensions and ventricular volumes

↑ Maximal stroke volume

↑ Maximal cardiac output


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Training ForLong -Term Endurance

Plasma

Volume

Red Cell

Mass

Blood Volume

Venous

Return

Ventricular

Volume

End Diastolic

Volume

Maximal Stroke Volume

Muscle Capillary

Density

Maximal Muscle BloodFlow

Oxygen

Delivery

VO2maxExercise to

VO2max

Maximal Cardiac

Output

Chronicadaptations ofthe CV systemafter exposure

to training forlong termendurance.

Adaptationsare related totheir aectduring both


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Training For

Long-Term Endurance

Plasma

Volume

Red Cell

Mass

Blood Volume

Venous

Return

Ventricular

Volume

End Diastolic

Volume

Stroke Volume

SympatheticStimulation

Heart

Rate

SubmaximalSteady State Exercise

Chronic

adaptations ofthe CV systemafter exposureto training forlong termendurance.

Adaptationsare related totheir aectduring bothmaximal &submaximal

exercise


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PULMONARY ADAPTATIONS TO

EXERCISE

After the onset of exercise there is: A rapid ↑ in ventilation

A similar rapid ↑ in pulmonary blood flow

An improved VEvs Q relationship in the lung

↑ Lung compliance

Airway dilation and ↓ resistance to air flow

The lungs and pulmonary circulation do not

express the degree of long-term adaptations to

exercise. The improvement are more determinedby muscular and cardiovascular function.


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Endocrine Adaptations to

Exercise


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fmd2- k30 - fs_exercise physiology

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