What Adaptations Occur With Cardiovascular Training? Flashcards
Heart rate:
no. of heart beats/min
End diastolic volume
volume of blood in left ventricle just prior to
contraction
End systolic volume
volume of blood in left ventricle following contraction
Stroke volume:
volume of blood ejected from the left ventricle with each heart beat (difference between EDV-ESV)
cardiac output
total volume of blood ejected from the heart per minute (equal to HR x SV)
a-v O2difference
artery - venus
difference in partial pressure of oxygen between the blood in the arterial and venous systems. Reflects amount of O2extracted from blood
CV SYSTEM OVERVIEW
The CV system supplies O2 for metabolism, eliminates CO2 producedduringmetabolism, and regulates H+ concentration to maintain acid-base balance
The exchange of O2 and CO2 occurs in the alveoli of the lungs the blood gas interface.
CV SYSTEM OVERVIEW - Heart
delivers oxygen and nutrients to the muscles and removes waste products by pumping blood through the CV system
CV SYSTEM OVERVIEW - Lungs
oxygenate the blood and remove CO2
CV SYSTEM OVERVIEW - vessels
delivers blood to tissues and from tissues
How is O2 transported in the blood?
98.5% bound to hemoglobin in red blood cells (remaining 1.5% dissolved in plasma)
How is CO2 transported in the blood?
- Dissolved in plasma (7%)
- Carbamino compounds (23%) – bound to Hb inside red
blood cells - Bicarbonate ions (HCO3-) (70%) – in RBC CO2 reacts
with water to form carbonic acid which dissolves into H+ and bicarbonate (HCO3-)
NORMAL RESTING VALUES - HR
60-100 beats per minute. This value can decrease with improved fitness and increase with age.
NORMAL RESTING VALUES - BP
BP can vary with changes in posture, exercise, stress or sleep, it should normally be 120/80 mm Hg for an adult age 20 or over. >140/ 90 mmHg is considered mild hypertension and >180/110 mmHg is considered a hypertensive crisis. <90/60 mmHg is considered hypotensive.
NORMAL RESTING VALUES - Respiratory rate:
12 -20 breaths per minute (12 breaths per minute is considered normal for an adult)
EXERCISE IS ABOUT TO START
Changes in respiration occur even before the initiation of exercise
Increased gas exchange across the alveolar-capillary membrane by the first or second breath.
– Increased respiratory rate
EXERCISE IS ABOUT TO START
Exercise Pressor / Anticipatory Response:
Increased SNS activity, release of norepinephrine and epinephrine
– includes generalized peripheral vasoconstriction in non-exercising muscles and viscera, an increased myocardial contractility, an increased heart rate, and an increased systolic blood pressure.
DURING EXERCISE
CARDIOVASCULAR AND RESPIRATORY SYSTEMS MUST MEET THE RAPID INCREASE IN ENERGY REQUIREMENTS DURING EXERCISE
Increased cardiac output Increased minute ventilation Increase in heart rate
DURING EXERCISE - CHANGE IN CO2
There is a marked increase and redistribution of the cardiac output.
This occurs due to a combination of the anticipatory response and a locally mediated reduction in resistance in the working muscle arterial vascular bed, independent of the autonomic nervous system, and is produced by metabolites such as Mg2+, Ca2+, adenosine diphosphate (ADP), increased PCO2, decreased PO2, increased lactic acid, and increased temperature.
DURING EXERCISE - MINUTE VENTILATION
Minute ventilation (the volume of air in inspired or expired per minute ) increases
MV increases as respiratory frequency and tidal volume increase. Alveolar ventilation, occurring with the diffusion of gases across the
capillary-alveolar membrane, increases 10-20x during heavy exercise to supply the additional O2 needed and excrete the excessive CO2 produced.
• What causes the observed increase in MV?
– Acombinationofneuralandchemicalfactors,anyofwhich
alone or in combination may stimulate the respiratory system:
• Increased muscle metabolism results in more O2 extraction from arterial blood (increased a-VO2 difference) resulting in an increase in venous PCO2 and H+, an increase in body temp, increased epinephrine, and increased stimulation of receptors of the joints and muscles
– ThingsotherthanexercisecaninfluenceMV-Baroreceptor reflexes, protective reflexes, pain, emotion, and voluntary control of respiration may also contribute to the increase in respiration
HR DURING EXERCISE
This depends on the intensity. If exercise intensity continues to increase HR will also continue to increase in a linear fashion until the maximum HR (HRmax) is achieved.
• If intensity is maintained at a submaximal level, HR increases rapidly until a plateau is reached. This is referred to as the
steady-state HR. This is the optimal HR for meeting the circulatory demands at a specific rate of work.
EXERCISE RESULTS IN ADAPTATIONS
The cardiovascular system and the muscles adapt to a training stimulus over time
Adaptations result in improved efficiency of the cardiovascular system and the active muscles at rest and during exercise
Adaptation is relative to baseline fitness – an individual with low level of fitness has more potential to improve.
ADAPTATIONS - CARDIOVASCULAR CHANGES
Cardiac adaptations:
Hypertrophy of cardiac muscle, increased left ventricular internal dimension, end diastolic volume, increased stroke volume (Frank- Starling Mechanism), increased myocardial mass, decreased HR at a given workload, rapid return to resting HR
Peripheral adaptations:
capillary density, increased red blood cells and total blood volume, increased a – vO2 difference at submaximal and maximal loads
ADAPTATIONS - BLOOD FLOW AND PRESSURE
• Increased ability to supply blood to muscles (blood flow) – Increasedcapillarisation
– Increasedabilitytodilate
• Decrease in resting blood pressure in hypertensive individuals
ADAPTATIONS - BLOOD VOLUME
Increased blood plasma volume
– Releaseofaldosteroneandantidiuretichormonewithexercise – Increasedplasmaproteins
• Increased number of red blood cells – Decreasedbloodviscosity
– Higherturnoverofcells
ADAPTATIONS - RESPIRATORY CHANGES
• Ventilatory efficiency is increased
• Minimal changes in lung volumes
• Small decrease in resting and sub-maximal respiratory rate
• Improvements during exercise
– Maximal minute ventilation
– Oxygendiffusioncapacityincreasesduetoincreased capillarisation
ADAPTATIONS - METABOLIC CHANGES
- Increased size and number of skeletal muscle mitochondria – increasing capacity to generate energy aerobically
- Increased myoglobulin – increasing rate of transport of oxygen transport
- Decreased rate of depletion of muscle glycogen
- Lower blood lactate levels at submaximal work
VO2 MAX
The integrated result of these adaptations is to increase the maximum amount of oxygen used by the body during dynamic exercise.
This is referred to as the VO2max (in L/min or ml/kg/min)
VO2 MAX DEF
the maximal CO (represents the oxygen delivery and blood flow to metabolically active tissue) and the maximal a-v O2 difference (the ability of metabolically active tissue to extract and use O2 from the blood)
VO2max = COmax x a-v O2 Diffmax
AT 12 DAYS
DECREASE IN VO2 MAX, CARDIAC OUTPUT STROKE VOL
INCREASE IN A-V O2 DIF MAX. , HR PEAKS
2ND DECREASE BY 21 DAYS
tidal vol.
The amount of air which enters the lungs during normal inhalation at rest.
norm = 500ml
